Q1.
The chart shows the processes involved in the manufacture of nitric acid from ammonia.
(a)
Complete the word equation for the reaction that takes place in the first reaction vessel.
ammonia + ......................................
nitrogen monoxide + water
(1)
(b)
What is the use of the platinum gauze in the reaction vessel?
.....................................................................................................................................
(1)
(c)
To convert nitrogen monoxide into nitric acid, two further reactants are needed.
What are they?
................................................................ and ............................................................
(1)
(d)
Complete the word equation below, to show how to make the fertiliser, ammonium nitrate.
................................ + .........................
ammonium nitrate + water
(2)
Page 1 of 95
(e)
Calculate the percentage of nitrogen in the fertiliser, ammonium nitrate NH4NO3.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 7 marks)
##
Here is a symbol equation, with state symbols, for a chemical reaction between solutions of
lead nitrate and potassium chloride.
Pb (NO3)2 (aq)
+
2 KCl (aq)
2KNO3 (aq)
+
PbCl2 (s)
The equation tells you the formulae of the two products of the reaction.
(a)
What are the names of the two products?
1 .................................................................................................................................
2 .................................................................................................................................
(2)
(b)
What else does the equation tell you about these products?
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(2)
(Total 4 marks)
Q3.
Here is a word equation for a chemical reaction.
copper oxide + sulphuric acid
copper sulphate + water
Write down everything that the word equation tells you about the reaction.
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
(Total 4 marks)
Page 2 of 95
Q4.
When a solution of lead nitrate is added to a solution of sodium chloride, a white precipitate
of lead chloride is produced.
(a)
(i)
Why is a precipitate formed?
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Complete and balance the equation for this precipitation reaction.
Pb+2(aq) +
Cl–(aq) →
(3)
(b)
Complete the table below by writing in the name and formula of the precipitate formed for
each reaction. If there is no precipitate, write “no precipitate”.
(5)
(Total 9 marks)
Page 3 of 95
Q5.
Sodium carbonate reacts with acids.
(i)
Complete the word equation.
sodium carbonate + hydrochloric acid → sodium chloride + ...................... + water
(1)
(ii)
Name the salt produced if sodium carbonate reacts with dilute nitric acid.
...........................................................................................................................
(1)
(Total 2 marks)
Q6.
The diagrams show what happens when an acid is added to an alkali.
(a)
What is present in the solution at stages 2 and 3 apart from universal indicator and water?
(i)
At stage 2 .........................................................................................................
(ii)
At stage 3..........................................................................................................
(3)
(b)
Write an ionic equation to show how water is formed in this reaction and state the
sources of the ions.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
(Total 6 marks)
Page 4 of 95
Q7.
The diagrams show what happens when an acid is added to an alkali.
(a)
What is present in the flask at stage 2, besides universal indicator and water?
.....................................................................................................................................
(1)
(b)
Write an ionic equation to show how water is formed in this reaction and state the sources
of the ions.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
(Total 4 marks)
Q8.
Read the passage carefully and then answer the questions.
The electrolysis of acidified water
After a few drops of dilute sulphuric acid have been added to some distilled water,
there will be three types of ion in solution:
from the water, H2O(l) → H+(aq) + OH–(aq)
from the acid,
H2SO4(aq) → 2H+(aq) + SO42– (aq)
When the electrodes (anode and cathode) in a circuit are put into the acidified water,
the hydroxide ions and the sulphate ions are both attracted to the electrode called the
anode. However, it is harder for the sulphate ions to give up their electrons than for
the hydroxide ions to do this. So the hydroxide ions are the ones which react and
bubbles of oxygen are formed at the anode.
There are only hydrogen ions to be attracted towards the cathode and, when they get
there, they take up electrons to form hydrogen molecules.
From Chemistry Matters by Richard Hart, reproduced by permission of Oxford University Press
Page 5 of 95
Even in a small volume of water acidified with dilute sulphuric acid there will be billions of ions.
Some will be anions and some will be cations.
(i)
Name the ions in water acidified with dilute sulphuric acid.
.....................................................................................................................................
(1)
(ii)
Explain why only some of the ions are attracted to the anode.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(iii)
Balance the equation for the reaction of hydroxide ions at the anode.
4OH– → H2O + O2 + e–
(1)
(Total 4 marks)
Q9.
(a)
Ammonium sulphate is made by the reaction:
2NH3(aq) + H2SO4(aq) →(NH4)2SO4(aq)
(i)
Complete the three answers in the table.
Question
Answer
How many hydrogens are there in
the formula of ammonium sulphate?
..............................................................
What is the name of the substance
with the formula NH3?
..............................................................
What is the name of the substance
with the formula H2SO4?
..............................................................
(3)
(ii)
What is the main use for ammonium sulphate?
...........................................................................................................................
(1)
(iii)
A similar reaction is used to make ammonium nitrate. What is the name of the acid
which must be used?
...........................................................................................................................
(1)
Page 6 of 95
(b)
NH3 is made by the reversible reaction:
N2(g) + 3H2(g)
(i)
2NH3(g)
Explain what the term reversible reaction means.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(ii)
What is the name of the raw material which is the source of nitrogen (N2)?
...........................................................................................................................
(1)
(iii)
Nitrogen is an element. Explain what the term element means.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(Total 10 marks)
Q10.
Ammonium nitrate and ammonium sulphate are used as fertilisers.
Page 7 of 95
(i)
Which acid reacts with ammonia to form ammonium nitrate?
....................................................................................................................................
(1)
(ii)
Which acid reacts with ammonia to form ammonium sulphate?
....................................................................................................................................
(1)
(iii)
The reactions in (i) and (ii) are both exothermic. How can you tell that a reaction is
exothermic?
....................................................................................................................................
....................................................................................................................................
(1)
(iv)
The reactions in (i) and (ii) are both examples of acid + base reactions. What is the name
of the chemical change which takes place in every acid + base reaction?
....................................................................................................................................
(1)
(Total 4 marks)
Page 8 of 95
Q11.
The flow diagram shows how to make ammonia and nitric acid from the nitrogen in the air.
(a)
A fertiliser is made by neutralising ammonia with nitric acid. What is the name of this
fertiliser?
.....................................................................................................................................
(1)
(b)
In the flow diagram, why are two different catalysts used?
.....................................................................................................................................
.....................................................................................................................................
(1)
(c)
What happens to catalysts at the end of a reaction?
.....................................................................................................................................
.....................................................................................................................................
(1)
(d)
Explain why catalysts are used in many industrial chemical reactions.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
Page 9 of 95
(e)
Explain, in terms of collisions between molecules, why a high pressure is used in the
reaction between nitrogen and hydrogen.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 7 marks)
Q12.
The flow diagram shows some stages in the manufacture of the fertiliser ammonium
nitrate (NH4NO3).
(a)
The elements needed to make ammonia (NH3) are obtained from natural gas and air.
Which element is obtained from the air?
.....................................................................................................................................
(1)
(b)
The word equation for the formation of nitrogen monoxide is:
ammonia + oxygen → nitrogen monoxide + water
The platinum catalyst needs to be heated only at the start of the reaction.
Suggest why.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(1)
(c)
Name the liquid A that reacts with nitrogen dioxide (NO2) to produce nitric acid (HNO3).
.....................................................................................................................................
(1)
Page 10 of 95
(d)
Describe how ammonium nitrate (NH4NO3) can be made from two of the products shown
in the flow diagram.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 5 marks)
Q13.
(a)
Magnesium burns in oxygen, forming magnesium oxide.
This equation represents the reaction.
Mg (s) + O2 (g) → MgO (s)
(i)
Balance the equation.
(1)
(ii)
Give the meaning of the state symbols (s) and (g).
(s) ..............................................
(g) ..............................................
(2)
(b)
Use the Formulae of Some Common Ions table on the Data Sheet to help you to answer
this question.
Magnesium also reacts with chlorine to form magnesium chloride.
Give the formula of magnesium chloride ..................................................................
(1)
(Total 4 marks)
Page 11 of 95
Q14.
Use the Formulae of Some Common Ions table on the Data Sheet to help you to answer
this question.
Acids react with alkalis to form salts and water.
Complete the table below by writing in the name and formula of the salt formed in each reaction.
The first one has been done for you.
Acid
Alkali
Salt
Formula of salt
Hydrochloric acid
Sodium hydroxide
Sodium chloride
NaCl
Nitric acid
Sodium hydroxide
Sulphuric acid
Potassium hydroxide
(Total 4 marks)
Q15.
This item appeared in the Wolverhampton Express and Star on October 31st, 1997.
Read the passage and answer the questions that follow.
Fumes scare at
factory
Workers were forced to flee a
factory after a chemical alert.
The building was evacuated
when a toxic gas filled the
factory.
It happened when nitric acid
spilled on to the floor and mixed
with magnesium metal powder.
(a)
The equation which represents the reaction between magnesium and nitric acid is:
Mg(s) + 4HNO3(aq) → Mg(NO3)2(aq) + 2H2O(1) + 2NO2(g)
Give the formula of the toxic gas that was produced.
....................................................................................................................................
(1)
(b)
Explain, in terms of particles, how the toxic gas was able to fill the factory quickly.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(2)
Page 12 of 95
(c)
The reaction of nitric acid with magnesium metal powder is more dangerous than if the
acid had fallen on to the same mass of magnesium bars. Explain why.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(1)
(d)
(i)
Water was sprayed on to the magnesium and nitric acid to slow down the reaction.
Explain, in terms of particles, why the reaction would slow down.
..........................................................................................................................
..........................................................................................................................
..........................................................................................................................
(2)
(ii)
Explain why it is better to add alkali, rather than just add water to the spillage.
..........................................................................................................................
..........................................................................................................................
(1)
(Total 7 marks)
Q16.
(i)
Which acid from the list should the student add to sodium hydroxide solution to make
sodium sulphate?
ethanoic acid
hydrochloric acid
nitric acid
sulphuric acid
.....................................................................................................................................
(1)
(ii)
When the acid was added to the alkali the beaker became warm.
Name the type of reaction that releases heat.
.....................................................................................................................................
(1)
(iii)
Use the Data Sheet to help you to write the formula of sodium sulphate.
Formula: .....................................................................................................................
(1)
(Total 3 marks)
Page 13 of 95
Q17.
Some drain cleaners contain a mixture of sodium hydroxide and powdered aluminium.
When the mixture is poured into a drain it mixes with water and a chemical reaction takes place.
The heat from the reaction helps to melt grease in the drain. Hydrogen gas is produced which
stirs up the particles and helps to unclog the drain.
(a)
Balance the equation for the reaction.
2Al(s) + ........ NaOH(aq) + ......... H2O → .........NaAl(OH)4(aq) + 3H2
(2)
(b)
Why do the solid sodium hydroxide and aluminium powder not react when stored in a
sealed container?
.....................................................................................................................................
(1)
(c)
Sodium hydroxide is a strong alkali and would react with any acids in the drain.
(i)
Name the ion produced when any alkali is dissolved in water.
...........................................................................................................................
(1)
(ii)
Name the ion produced when any acid is dissolved in water.
...........................................................................................................................
(1)
(iii)
Name the compound formed when these ions react with each other.
...........................................................................................................................
(1)
(Total 6 marks)
##
Sando-K is a medicine. It is given to people whose bodies contain too little of a particular element.
Sando-K is a mixture of two compounds. The formulae of the two compounds are given below.
KHCO3
(a)
KC1
Which metal do people given Sando-K need?
.....................................................................................................................................
(1)
(b)
Sando-K contains the ion, CO32–. Which gas would be produced if a dilute acid was added to
Sando-K? (The Data Sheet may help you to answer this question.)
.....................................................................................................................................
(1)
Page 14 of 95
(c)
The compounds in Sando-K contain ions.
Complete the two sentences below.
Atoms change into positive ions by ....................................... one or more
............................................................. .
Atoms change into negative ions by ......................................... one or
more .................................................... .
(4)
(d)
Electricity can be used to show that an aqueous solution of Sando-K contains ions.
(i)
Draw a diagram of an apparatus that you could use to prove that Sando-K
contains ions.
(4)
(ii)
Explain, as fully as you can, what would happen when the electricity is switched on.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
(Total 13 marks)
Page 15 of 95
Q19.
Sodium carbonate is a useful chemical that can be made from sodium chloride.
(a)
The flow chart below shows one way in which sodium carbonate can be made.
(i)
Write the formula of sodium carbonate.
Use the Data Sheet to help you to answer this question.
...........................................................................................................................
(1)
(ii)
1.
Give one example of a thermal decomposition reaction shown in the
flow chart.
................................................................................................................
................................................................................................................
(1)
2.
Explain what is meant by a thermal decomposition reaction.
................................................................................................................
................................................................................................................
(2)
(iii)
Name one substance that is recycled in this process.
...........................................................................................................................
(1)
Page 16 of 95
(b)
When sodium carbonate solution is added to zinc sulphate solution a white solid
is precipitated.
(i)
Use the Data Sheet to help you to name the white solid that is produced in this
reaction.
...........................................................................................................................
(1)
(ii)
State why this solid is formed.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
(Total 7 marks)
Q20.
(a) In an industrial process electricity is passed through a solution of sodium chloride in
water. A student set up the apparatus shown below to investigate this process.
(i)
Name gas X.
...........................................................................................................................
(1)
(ii)
Complete the half equation for the production of chlorine gas during the electrolysis.
............ Cl–
→ ............ e–
→
Cl2
(1)
(iii)
The student found that the solution left in the cell was alkaline.
Which ion makes the solution alkaline?
...........................................................................................................................
(1)
Page 17 of 95
(iv)
Name the useful substance that can be obtained from the solution in the cell.
...........................................................................................................................
(1)
(b)
Sodium carbonate is another useful chemical that can be made from sodium chloride. The
flow chart below shows one way in which sodium carbonate can be made.
(i)
Write the formula of sodium carbonate.
Use the Data Sheet to help you to answer this question.
...........................................................................................................................
(1)
(ii)
Salt is one raw material used in this process.
Name one other raw material used in this process.
...........................................................................................................................
(1)
(iii)
Sodium carbonate is one of the products of this process.
Name one other product.
...........................................................................................................................
(1)
Page 18 of 95
(iv)
1. Give one example of a thermal decomposition reaction shown in the
flow chart.
................................................................................................................
................................................................................................................
(1)
2.
Explain what is meant by a thermal decomposition reaction.
................................................................................................................
................................................................................................................
(2)
(v)
Name one substance that is recycled in this process.
...........................................................................................................................
(1)
(c)
When sodium carbonate solution is added to zinc sulphate solution a white solid
is precipitated.
(i)
Use the Data Sheet to help you to name the white solid that is produced in this
reaction.
...........................................................................................................................
(1)
(ii)
State why this solid is formed.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
(Total 13 marks)
Page 19 of 95
Q21.
(a)
This label has been taken from a packet of Andrews Antacid.
(i)
Write the simplest ionic equation which represents a neutralisation reaction.
...........................................................................................................................
(1)
(ii)
Chewing the tablet cures indigestion faster than swallowing the tablet whole. Explain
why.
...........................................................................................................................
...........................................................................................................................
(1)
(iii)
Write the formula of the magnesium compound present in Andrews Antacid.
You may find the Data Sheet helpful.
...........................................................................................................................
(1)
(b)
The active ingredients in the Antacid react with hydrochloric acid in the stomach to give
salts, water and carbon dioxide.
A student investigated how quickly the tablets react with excess hydrochloric acid.
40 cm³ of dilute hydrochloric acid were placed in a conical flask. The flask was placed on
a direct reading balance. Two Antacid tablets were quickly added to the flask. The
apparatus was weighed immediately. At the same time, a stop clock was started. The
mass was recorded every half minute for 5 minutes.
The results are shown in the table below.
The main active ingredient in Andrews Antacid is calcium carbonate.
Page 20 of 95
(i)
Balance the equation which represents the reaction between calcium carbonate and
hydrochloric acid.
CaCO3(s) + .......... HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g)
(1)
(ii)
State the meaning of the symbol “(aq)”.
...........................................................................................................................
(1)
(iii)
Why does the mass of the flask and contents decrease?
...........................................................................................................................
(1)
(c)
(i)
Plot the results on the graph below and draw a smooth curve to show how the mass
of the flask and its contents changes with time. Label this curve “A”.
(3)
(ii)
One of the results does not appear to fit the pattern. Circle this result on the graph.
(1)
Page 21 of 95
(d)
The student did a second experiment. The only change was that the acid was twice as
concentrated.
On the graph, sketch a second curve to show a possible result for this experiment. Label
this curve “B”.
(2)
(Total 12 marks)
Q22.
Limestone (CaCO3) is a raw material. On strong heating it is converted to calcium oxide
which is a very useful substance.
(a)
Calculate the formula mass (Mr) of calcium carbonate.
.....................................................................................................................................
Mr of calcium carbonate = ...............................................
(2)
(b)
About 60 million tonnes of calcium oxide is made in Britain each year.
Calculate the mass of calcium carbonate needed to make this amount of calcium oxide.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
Mass of calcium carbonate needed = .............................. million tonnes
(4)
(c)
Water is added to some of the calcium oxide produced in a process known as ‘slaking’.
The product of this reaction is used to make plaster.
CaO(s) + H2O(1)→ Ca(OH)2(s)
(i)
Give the chemical name of Ca(OH)2.
..........................................................................................................................
(1)
Page 22 of 95
(ii)
What is the physical state of the Ca(OH)2 formed in the reaction?
..........................................................................................................................
(1)
(Total 8 marks)
Q23.
The salt sodium hydrogen phosphate (Na2HPO4) is used as a softening agent in
processed cheese.
It can be made by reacting phosphoric acid (H3PO4) with an alkali.
(a)
Complete the name of an alkali that could react with phosphoric acid to make sodium
hydrogen phosphate.
....................................... hydroxide
(1)
(b)
What is the name given to a reaction in which an acid reacts with an alkali to make a salt?
.....................................................................................................................................
(1)
(c)
How would the pH change when alkali is added to the phosphoric acid solution?
.....................................................................................................................................
.....................................................................................................................................
(1)
(d)
What ions are present when any acid is dissolved in water?
.....................................................................................................................................
(1)
(e)
What ions are present when any alkali is dissolved in water?
.....................................................................................................................................
(1)
Page 23 of 95
(f)
Write a chemical equation for the reaction which takes place between the ions you have
named in (e) and (f).
.....................................................................................................................................
(1)
(Total 6 marks)
Q24.
Ammonia and nitric acid are both important chemicals. Nitric acid is made from ammonia.
The charts below show substances made from ammonia and nitric acid.
(a)
Use the charts to help you answer these questions.
(i)
What is the main use of both ammonia and nitric acid?
..........................................................................................................................
(1)
(ii)
Work out the percentage of ammonia used to make nitric acid.
Percentage = ........................ %
(1)
(iii)
100 million tonnes of ammonia are made in the world each year.
How much of this ammonia is used to make nylon?
.......................... million tonnes
(1)
(b)
The word equations below show how nitric acid is made.
1.
nitrogen + hydrogen → ammonia
2.
ammonia + oxygen → nitrogen monoxide + water
3.
nitrogen monoxide + oxygen → nitrogen dioxide
4.
nitrogen dioxide + water → nitric acid
Page 24 of 95
Use the word equations to help you answer these questions.
(i)
From which two elements is ammonia made?
......................................................... and .........................................................
(1)
(ii)
Name two of the raw materials needed to make nitric acid.
......................................................... and .........................................................
(2)
(c)
A large amount of nitric acid is reacted with ammonia to make a fertiliser.
nitric acid + ammonia → fertiliser
(i)
The reaction is a neutralisation reaction.
What type of chemical must ammonia be?
...........................................................................................................................
(1)
(ii)
Complete the chemical name for the fertiliser made from ammonia and nitric acid.
ammonium ....................................................
(1)
(iii)
The reaction of nitric acid with ammonia is exothermic.
Name the piece of equipment you could put into the solution to prove that the reaction
is exothermic.
...........................................................................................................................
(1)
(Total 9 marks)
Q25.
This article appeared in a newspaper.
(a)
The balanced chemical equation shows the reaction between steel and hydrochloric acid.
Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)
Page 25 of 95
(i)
Which metal in steel reacted with the hydrochloric acid?
...........................................................................................................................
(1)
(ii)
The gas released was described as explosive. Explain why.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
(b)
In the factory hydrogen chloride is manufactured by reacting hydrogen with chlorine.
Hydrochloric acid is formed when hydrogen chloride forms a solution in water.
(i)
Water was sprayed on the steel and hydrochloric acid. This slowed the rate of
reaction. Explain why.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(ii)
It would have been better to neutralise the acid with an alkali rather than to just add
water. Hydrochloric acid can be neutralised by reaction with sodium hydroxide.
Complete the ionic equation for the neutralisation reaction.
(aq) + (aq) → H2O(l)
(2)
(iii)
In the factory the acid leak was neutralised with slaked lime, Ca(OH)2, and not
sodium hydroxide, NaOH. Suggest why.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(Total 10 marks)
Page 26 of 95
Q26.
Calcium tablets are taken to build and maintain strong bones and teeth.
(a)
These tablets react with hydrochloric acid in the stomach.
CaCO3( ) + 2HCl(aq) → CaCl2(
(i)
) + H2O(
) + CO2(
Add all these missing state symbols
equation.
)
to the balanced chemical
(2)
(ii)
The calcium salt that is formed is absorbed during digestion. What is the name of the
calcium salt?
...........................................................................................................................
...........................................................................................................................
(1)
(b)
The volume of carbon dioxide produced by one calcium tablet in the stomach can be found
as shown.
The volume of carbon dioxide was recorded every 30 seconds until the reaction stopped.
Time in seconds
0
30
60
90
120
150
180
210
240
Volume of gas in
cm3
0
24
36
46
52
56
59
60
60
Page 27 of 95
(i)
Complete the graph of these results.
(3)
(ii)
Describe one way in which this reaction can be made to go faster.
...........................................................................................................................
...........................................................................................................................
(1)
(iii)
A calculation, using the mass of this tablet, showed that 80 cm3 of carbon dioxide
would be produced if the tablet was pure calcium carbonate. What do the results
show about the purity of the tablet? Explain your answer by calculating the purity of
this tablet.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
(Total 10 marks)
Page 28 of 95
Q27.
Many everyday substances can be classified as acids, bases or salts. For example, car
batteries contain sulphuric acid, oven cleaners contain sodium hydroxide and table salt contains
sodium chloride.
(a)
A solution of each of these substances was tested with universal indicator.
Solution
Colour of universal indicator
Sulphuric acid (H2SO4)
red
Sodium hydroxide (NaOH)
purple
Sodium chloride (NaCl)
green
(i)
Explain how these universal indicator colours and the corresponding pH values could
be used to identify each of these solutions.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(3)
(ii)
Name and give the formula of the ion which causes the solution to be acidic.
Name of ion ..................................................................................................
Formula of ion .................................................................................................
(2)
(b)
Sodium chloride can be made by reacting sodium hydroxide with hydrochloric acid in the
presence of an indicator.
(i)
What is the name of this type of reaction?
..........................................................................................................................
(1)
(ii)
Write a balanced chemical equation for this reaction.
..............(aq) + ..............(aq) → ..............(aq) + ..............(l)
(2)
Page 29 of 95
(c)
The atomic number for sodium is 11 and for chlorine is 17.
(i)
Complete the diagrams to show the electron arrangements for a sodium atom and a
chlorine atom.
(2)
(ii)
These atoms form different particles by one electron transferring from the sodium
atom to the chlorine atom. What is the name given to the particles formed?
...........................................................................................................................
(1)
(iii)
Why do these sodium and chloride particles bond?
...........................................................................................................................
...........................................................................................................................
(1)
(d)
Sodium chloride solution is electrolysed to form three products, hydrogen, chlorine and
sodium hydroxide.
Page 30 of 95
Describe how each of these products are formed.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
(Total 15 marks)
Q28.
Acids and bases are commonly found around the home.
(a)
Baking powder contains sodium hydrogencarbonate mixed with an acid.
(i)
When water is added, the baking powder releases carbon dioxide. How could you
test the gas to show that it is carbon dioxide?
Test ..................................................................................................................
Result of test ....................................................................................................
(2)
(ii)
Complete and balance the chemical equation for the reaction of sodium
hydrogencarbonate with sulphuric acid.
NaHCO3 + H2SO4 → ....................... + ........................ + ..................
(2)
(b)
Indigestion tablets contain bases which cure indigestion by neutralising excess stomach
acid.
(i)
One type of indigestion tablet contains magnesium hydroxide. This base neutralises
stomach acid as shown by the balanced chemical equation.
Mg(OH)2 + 2HCl → MgCl 2 + 2H2O
Write a balanced ionic equation for the neutralisation reaction.
..........................................................................................................................
(2)
Page 31 of 95
(ii)
How does the pH in the stomach change after taking the tablets?
..........................................................................................................................
(1)
(c)
Ammonium sulphate is used as a lawn fertiliser.
Using ammonia solution, describe how you would make the fertiliser ammonium sulphate.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(3)
(Total 10 marks)
Page 32 of 95
Q29.
A student investigated the electrolysis of lead bromide.
Lead bromide was placed in the tube and the circuit was switched on. The light bulb did not light
up.
The tube was heated and soon the bulb lit up. The observations are shown in the table.
(a)
Positive electrode
Negative electrode
red-brown gas
silver liquid
What is meant by electrolysis?
....................................................................................................................................
(2)
(b)
Why did the lead bromide conduct electricity when the tube was heated?
....................................................................................................................................
(1)
(c)
Name the substances formed at the:
positive electrode; .....................................................................................................
negative electrode. ....................................................................................................
(2)
(d)
Suggest one safety precaution that should be taken during this investigation.
....................................................................................................................................
(1)
(Total 6 marks)
Page 33 of 95
Q30.
A student tried to make some magnesium sulphate. Excess magnesium was added to
dilute sulphuric acid. During this reaction fizzing was observed due to the production of a gas.
(i)
Complete and balance the chemical equation for this reaction.
..................... + H2SO4 → ....................... + ........................
(3)
(ii)
At the end of the reaction the solution remaining was filtered. Why was the solution
filtered?
.....................................................................................................................................
(1)
(iii)
The filtered solution was left in a warm place.
Explain why the filtered solution was left in a warm place.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(Total 6 marks)
Page 34 of 95
Q31.
Bordeaux Mixture controls some fungal infections on plants.
A student wanted to make some Bordeaux Mixture.
(a)
The student knew that calcium oxide could be made by heating limestone. Limestone
contains calcium carbonate, CaCO3.
(i)
Write the word equation for this reaction.
...........................................................................................................................
(1)
(ii)
What type of reaction is this?
...........................................................................................................................
(1)
(b)
The student knew that copper sulphate, CuSO4, could be made by the following general
reaction.
acid + base → salt + water
(i)
What type of reaction is this?
...........................................................................................................................
(1)
(ii)
The base used is copper oxide. Name and give the chemical formula of the acid
used.
Name ................................................................................................................
Chemical formula .............................................................................................
(2)
Page 35 of 95
(c)
The student wrote about how the copper sulphate was made.
“Some of the acid was warmed. Copper oxide was added. The mixture was stirred. More
copper oxide was added until no more would react. The mixture was then filtered.”
(i)
Why was the acid warmed?
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Copper oxide was added until no more would react. Explain why.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(iii)
The filtration apparatus is shown.
Describe and explain what happens as the mixture is filtered.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(Total 10 marks)
Page 36 of 95
Q32.
(a)
The diagram shows one way of making crystals of copper sulphate.
(i)
Why was the solution filtered?
..........................................................................................................................
(1)
(ii)
How could you make the crystals form faster from the copper sulphate solution?
..........................................................................................................................
(1)
(iii)
The chemical equation is shown for this reaction.
CuO(s) + H2SO4(aq) → CuSO4(aq) + H2O(l)
In the chemical equation what does (aq) mean?
..........................................................................................................................
(1)
(b)
Blue copper sulphate crystals go white when warmed. How could you use the white
copper sulphate as a test for water?
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(2)
(Total 5 marks)
Page 37 of 95
Q33.
Explain, in terms of ions and molecules, what happens when any acid reacts with any
alkali.
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
...............................................................................................................................................
(Total 3 marks)
Q34.
The information in the box is about the preparation of copper sulphate crystals.
Step 1 Add a small amount of black copper oxide to some hot dilute sulphuric acid,
and stir.
Step 2 Keep adding copper oxide until it is in excess.
Step 3 Remove the excess copper oxide to leave blue copper sulphate solution.
Step 4 Evaporate the copper sulphate solution until it is saturated.
Step 5 Leave the saturated solution of copper sulphate to cool. Blue copper sulphate
crystals form on cooling.
Step 6 Remove the crystals from the solution remaining.
Step 7 Dry the blue crystals on a piece of filter paper.
(i)
Suggest a reason for using excess copper oxide in Step 2.
.....................................................................................................................................
.....................................................................................................................................
(1)
(ii)
Suggest how the excess copper oxide can be removed from the solution in Step 3.
.....................................................................................................................................
.....................................................................................................................................
(1)
(iii)
What is meant by the term saturated solution?
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
Page 38 of 95
(iv)
Why do crystals form when a hot saturated solution cools?
.....................................................................................................................................
.....................................................................................................................................
(1)
(v)
Suggest why the blue crystals are dried in Step 7 using filter paper instead of by heating.
.....................................................................................................................................
.....................................................................................................................................
(1)
(Total 6 marks)
Q35.
Salts can be prepared by the reaction of acids with alkalis.
(a)
(i)
The reactions of acids with alkalis can be represented by the equation below.
Choose a substance from the box to complete the equation.
carbon dioxide
hydrogen
oxygen
water
acid + alkali → salt + ..........................................................
(1)
(ii)
Draw a ring around the word which best describes the reaction.
displacement
neutralisation
oxidation
reduction
(1)
Page 39 of 95
(b)
Sodium sulphate is an important salt.
The table gives a list of some substances.
Put a tick ( ) next to the names of the acid and the alkali that would react to make sodium
sulphate.
Substances
( )
Hydrochloric acid
Nitric acid
Potassium sulphate
Sodium hydroxide
Sodium nitrate
Sulphuric acid
(2)
(Total 4 marks)
Q36.
The following passage is about the preparation of lead iodide, an insoluble salt.
An excess of potassium iodide in solution was shaken with
some lead nitrate solution in a test tube.
The lead iodide precipitate was separated from the mixture
and then washed several times with water.
The lead iodide was dried and then placed in a bottle.
(a)
Suggest a reason why excess potassium iodide was used.
.....................................................................................................................................
.....................................................................................................................................
(1)
(b)
What word used in the passage shows that lead iodide is insoluble?
....................................................................................................................................
(1)
(c)
Suggest how lead iodide can be separated from the mixture.
....................................................................................................................................
....................................................................................................................................
(1)
Page 40 of 95
(d)
Why was the lead iodide washed with water?
....................................................................................................................................
....................................................................................................................................
(1)
(e)
Suggest a method which could be used to dry this lead iodide.
....................................................................................................................................
....................................................................................................................................
(1)
(f)
Lead compounds are toxic.
Suggest a suitable safety precaution that should be taken when using toxic substances in
laboratories.
....................................................................................................................................
(1)
(Total 6 marks)
Q37.
Ammonium nitrate and potassium chloride are both salts. They can be made by
neutralisation reactions.
Choose substances from the box to complete the word equations for the formation of
these two salts.
ammonia
potassium nitrate
hydrochloric acid
water
nitric acid
potassium hydroxide
ammonia + ........................................ → ammonium nitrate + water
.................................. + hydrochloric acid → potassium chloride + ..........................
(Total 3 marks)
Q38.
Neutralisation reactions can be used to make salts.
(a)
Write an ionic equation for a neutralisation reaction, including state symbols.
.....................................................................................................................................
(2)
Page 41 of 95
(b)
Ammonium nitrate is a salt used as a fertiliser.
(i)
Ammonium nitrate is made by mixing two solutions. Name these solutions.
......................................................... and .........................................................
(1)
(ii)
Hazard information about ammonium nitrate states:
•
it is not itself a fire hazard (does not burn);
•
it must not be allowed to come into contact with combustible materials such as
fuels because it can cause these to catch fire.
Suggest why ammonium nitrate helps other substances to burn.
..........................................................................................................................
..........................................................................................................................
(1)
(Total 4 marks)
Q39.
Nitric acid can be neutralised by alkalis to make salts.
(i)
The salt called potassium nitrate can be made from nitric acid.
Complete the word equation for this neutralisation reaction.
Choose the correct substances from the box.
hydrogen
potassium hydroxide
oxygen
potassium chloride
water
nitric acid + ................................ →potassium nitrate + ................................
(2)
Page 42 of 95
(ii)
Ammonium nitrate is another salt made from nitric acid.
Which one of the following is the main use of ammonium nitrate? Draw a ring around your
answer.
dye
fertiliser
plastic
fuel
(1)
(iii)
Complete this sentence by choosing the correct ion from the box.
H+
NH4+
NO3–
O2–
OH–
The ion that makes solutions acidic is ............................................................ .
(1)
(Total 4 marks)
Q40.
Copper sulfate (CuSO4) is a salt that has many uses.
An aqueous solution of copper sulfate can be made by reacting copper oxide (CuO) with an
acid.
(a)
(i)
Name this acid. ...............................................................................................
(1)
(ii)
Write a balanced symbol equation, including state symbols, for this reaction.
.........................................................................................................................
(2)
(b)
Copper oxide reacts much faster with acid at 40 °C than at 20 °C.
Explain why in terms of particles.
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
(2)
(Total 5 marks)
Page 43 of 95
Q41.
This label was taken from a cola drink.
The pH of this drink is 2.5.
(a)
(i)
Which one of the ingredients in the cola drink causes the low pH?
..........................................................................................................................
(1)
(ii)
Draw a ring around the name of the ion that gives the cola drink its low pH.
chloride
hydrogen
hydroxide
sodium
(1)
(b)
The preservative used in the cola drink is sodium benzoate.
Sodium benzoate is made using two chemical reactions.
Reaction 1
Methylbenzene is reacted with oxygen, with the help of a catalyst, to form benzoic acid.
Reaction 2
Benzoic acid is neutralised by sodium hydroxide solution to form sodium benzoate and
water.
(i)
How does the catalyst help reaction 1?
..........................................................................................................................
..........................................................................................................................
(1)
Page 44 of 95
(ii)
Reaction 1 has a high atom economy.
The table lists several statements. Put a tick ( ) next to the one statement which
best describes a high atom economy.
Statement
( )
All the atoms used are cheap.
Most of the starting materials end up as useful products.
Only a small number of atoms are used in the reaction.
(1)
(iii)
Reaction 2 is a neutralisation reaction.
Complete the equation by writing the formula of the product.
H+
+
OH–
→
...................
(1)
(Total 5 marks)
Q42.
Photographic film often contains silver bromide. Silver bromide is changed by light to form
silver which appears as a black solid. This darkens the photographic film.
A photographic film can be made by coating thin transparent plastic with a gel containing silver
bromide.
The main steps in making this photographic film are as follows:
Step 1
Gelatine is dissolved in warm water to make a solution.
Step 2
Compound A, a soluble compound which contains bromide ions, is
dissolved into this solution.
Step 3
The lights are turned out in the darkroom.
Step 4
Compound B, a soluble compound which contains silver ions, is
dissolved in water.
Step 5
The solution of compound B is added to the solution containing
compound A and gelatine. Solid silver bromide is formed.
Step 6
The warm mixture is poured onto thin, transparent plastic film.
Step 7
The mixture sets to form a gel containing solid silver bromide.
Page 45 of 95
(a)
The table below gives information about the solubility of some compounds.
SOLUBLE
INSOLUBLE
All sodium and potassium salts
All nitrates
Most chlorides, bromides and iodides
Silver and lead chlorides, bromides and
iodides
Most sulfates
Lead sulfate and barium sulfate
Sodium, potassium and ammonium
carbonates
Most other carbonates
Use the table to help you to name suitable compounds for A and B.
Compound A ..............................................................................................................
Compound B ..............................................................................................................
(2)
(b)
Suggest why the lights are turned out at step 3 in this method of making a photographic
film.
....................................................................................................................................
....................................................................................................................................
(1)
(c)
What type of chemical reaction takes place when the compounds are mixed in step 5?
....................................................................................................................................
(1)
(d)
The photographic film is placed in a camera and a picture is taken. Where light hits the
photographic film the silver ions (Ag+) are changed into silver metal (Ag).
Explain why this reaction is a reduction.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(2)
(Total 6 marks)
Page 46 of 95
Q43.
(a) Write a balanced symbol equation for the reaction between magnesium (Mg) and
oxygen (O2) to form magnesium oxide (MgO).
.....................................................................................................................................
(1)
(b)
The diagram shows the electronic structure of a magnesium atom.
The atomic (proton) number of magnesium is 12.
Magnesium atom
Draw a similar diagram to show the electronic structure of an oxygen atom.
The atomic (proton) number of oxygen is 8.
(1)
(c)
Magnesium ions and oxide ions are formed when magnesium reacts with oxygen.
The diagram shows the electronic structure of an oxide ion.
Oxide ion
Draw a similar diagram to show the electronic structure of a magnesium ion.
(1)
Page 47 of 95
(d)
Magnesium oxide is a white solid with a high melting point.
Explain how the ions are held together in solid magnesium oxide.
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
(2)
(e)
Indigestion tablets can be made from magnesium oxide. The magnesium oxide neutralises
some of the hydrochloric acid in the stomach.
Complete the word equation for the reaction between magnesium oxide and hydrochloric
acid.
hydrochloric acid + magnesium oxide
→
......................
+
water.
(1)
(Total 6 marks)
Q44.
Distress flares are used to attract attention in an emergency.
Flares often contain magnesium. Magnesium burns to form magnesium oxide.
(a)
The distress flare burns with a bright flame because the reaction is very exothermic.
Complete the following sentence using the correct words from the box.
gives out heat
stores heat
takes in heat
An exothermic reaction is one which ..........................................................................
(1)
Page 48 of 95
(b)
The diagram shows the electronic structure of a magnesium atom.
The atomic (proton) number of magnesium is 12.
Magnesium atom
The atomic (proton) number of oxygen is 8.
Which diagram, A, B, C or D, shows the electronic structure of an oxygen atom?
Diagram ..............................
(1)
(c)
Magnesium ions and oxide ions are formed when magnesium reacts with oxygen. The
diagram shows the electronic structure of an oxide ion.
Oxide ion
Which diagram, J, K, L or M, shows the electronic structure of a magnesium ion?
Diagram ..............................
(1)
Page 49 of 95
(d)
Indigestion tablets can be made from magnesium oxide. The magnesium oxide neutralises
some of the hydrochloric acid in the stomach.
Draw a ring around the name of the salt formed when magnesium oxide reacts with
hydrochloric acid.
magnesium chloride
magnesium hydroxide
magnesium sulfate
(1)
(Total 4 marks)
Q45.
Read the article and then answer the questions that follow.
Hydrogen fuel for cars?
Hydrogen is an excellent fuel. It can be made by the electrolysis of potassium
hydroxide solution.
Hydrogen gas can be stored under pressure in a cylinder but a leak of the gas
could cause an explosion.
It has been found that lithium nitride can absorb and then release large volumes of
hydrogen. A chemical reaction takes place between the hydrogen and the lithium
nitride. The hydrogen is held in the resulting compounds by chemical bonds.
The problem is that the rate at which hydrogen is absorbed and then released
from normal sized particles of lithium nitride is slow.
Recently scientists have made ‘nanosized’ particles of lithium nitride. These
particles absorb hydrogen in the same way as normal sized lithium nitride
particles. The ‘nanosized’ particles have the advantage that they absorb and
release the hydrogen much faster when needed in the fuel cell.
It is hoped that ‘nanosized’ particles of lithium nitride may provide a safe method
of storing hydrogen in the future.
(a)
Hydrogen is produced at the negative electrode during the electrolysis of potassium
hydroxide solution.
(i)
Why are hydrogen ions attracted to the negative electrode?
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
Page 50 of 95
(ii)
Potassium ions are also attracted to the negative electrode.
Explain why hydrogen gas is formed but not potassium.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
(b)
Lithium nitride is made by reacting lithium with nitrogen.
Balance the equation for this reaction.
.......... Li + N2 → .......... Li3N
(1)
(c)
(i)
The equation for the reaction of lithium nitride with hydrogen is:
Li3N + 2H2
LiNH2 + 2LiH
What feature of this reaction allows the hydrogen to be released?
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Hydrogen stored in a fuel tank filled with lithium nitride would be safer in an accident
than a cylinder full of hydrogen.
Suggest and explain why.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(d)
Lithium nitride is an ionic compound which contains lithium ions (Li+) and nitride ions (N3–).
(i)
The formation of a lithium ion from a lithium atom is an oxidation reaction.
Explain why.
...........................................................................................................................
...........................................................................................................................
(1)
Page 51 of 95
(ii)
The diagram shows the electronic structure of a nitrogen atom.
Complete the diagram below to show the electronic structure of a nitride ion (N3–).
(1)
(Total 8 marks)
Q46.
(a)
Citric acid produces hydrogen ions in aqueous solution.
These ions can be represented as H+(aq).
Complete this sentence.
The (aq) means that the acid has been dissolved in .................................................. .
(1)
(b)
The diagram represents a hydrogen atom, H.
Use the diagram to explain why a hydrogen ion, H+, is a proton.
.....................................................................................................................................
.....................................................................................................................................
(1)
Page 52 of 95
(c)
Citric acid is a weak acid.
Draw a ring around the correct answer to complete the sentence.
has a low boiling point.
The word weak means that the acid
is dilute.
is partially ionised in water.
(1)
(d)
A student measured the pH of four acids, A, B, C and D.
The acids were the same concentration. The same quantity of magnesium ribbon was
added to each of the acids. The volume of gas produced after 5 minutes was recorded.
The results are shown in the table.
(i)
Acid
pH
Volume of gas in cm3
A
2
18
B
5
6
C
1
24
D
4
12
State one way in which the student made sure that the experiment was fair.
...........................................................................................................................
(1)
(ii)
Use the results to arrange the acids, A, B, C and D in order of decreasing acid
strength.
Most acidic ........................................................................................ Least acidic.
(1)
(e)
When acids react with alkalis, the hydrogen ions from the acid react with the hydroxide
ions from the alkali.
(i)
Which one of the following represents the formula of a hydroxide ion?
Draw a ring around your answer.
H–
O–
OH–
(1)
Page 53 of 95
(ii)
Draw a ring around the correct answer to complete the sentence.
acidic.
A solution with more hydrogen ions than hydroxide ions is
alkaline.
neutral.
(1)
(Total 7 marks)
Q47.
Ammonia has the formula NH3
The diagrams show how electrons are arranged in nitrogen and hydrogen atoms.
(a)
Draw a diagram to show how the electrons are arranged in an ammonia molecule.
You need only show the electrons in the highest energy level.
(2)
Page 54 of 95
(b)
Ammonia is a gas at room temperature.
Explain why ammonia has a low boiling point.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(c)
Ammonia dissolves in water to form a solution with a pH of about 10.
(i)
Name the ion in the ammonia solution that causes the pH of 10.
...................................................... ion
(1)
(ii)
Ammonium nitrate is made by reacting ammonia with an acid.
Name the acid.
...................................................... acid
(1)
(d)
Instant cold packs are used to treat sports injuries.
Page 55 of 95
One type of cold pack has a plastic bag with water inside. Inside the bag is a smaller bag
containing solid ammonium nitrate.
The outer bag is squeezed so that the inner bag bursts. The pack is shaken and quickly
gets cold as the ammonium nitrate dissolves in the water.
Explain why the bag gets cold.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 8 marks)
Q48.
Waste water from some industrial processes contains harmful metal ions, such as
chromium ions. Harmful metal ions must be removed from the water before the water is
returned to a river.
(a)
A method of removing chromium ions (Cr3+) from water is represented by this equation.
Balance the equation.
Cr3+(aq)
+
...........OH–(aq)
→
Cr(OH)3(s)
(1)
(b)
Suggest a suitable chemical that could be added to the water to provide the OH– ions.
........................................................................................................................
(1)
(c)
Explain how chromium ions are removed from the water.
........................................................................................................................
........................................................................................................................
(1)
(Total 3 marks)
Page 56 of 95
Q49.
In this question you will get marks on using good English, organising information clearly
and using specialist terms correctly.
Copper sulfate crystals can be made from copper oxide powder and dilute sulfuric acid.
Describe a method to make copper sulfate crystals from copper oxide and dilute sulfuric acid.
For the method you should include:
•
•
the names of the pieces of apparatus used
a risk assessment.
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
.................................................................................................................................
(Total 6 marks)
Q50.
Waste water from some industrial processes contains harmful metal ions, such as
chromium ions. These ions must be removed from the water before the water is returned to a
river.
The equation shows a method of removing chromium ions from water.
CrCl3(aq) + 3NaOH(aq)
→
Cr(OH)3(s)
+
3NaCl(aq)
Page 57 of 95
(a)
This type of reaction is called a precipitation reaction.
Describe what happens in a precipitation reaction
........................................................................................................................
........................................................................................................................
(1)
(b)
Complete the name of the substance with the formula NaOH.
Sodium ........................................
(1)
(c)
Draw a ring around the method that could be used to separate the Cr(OH)3(s) from the
water.
electrolysis
filtration
neutralisation
oxidation
(1)
(d)
It is important to remove chromium ions from water before it is returned to a river.
Suggest why.
........................................................................................................................
........................................................................................................................
(1)
(Total 4 marks)
Q51.
(a)
Ammonia has the formula NH3. It is made from nitrogen and hydrogen.
How many atoms are in an ammonia molecule? ..........................................
(1)
Page 58 of 95
(b)
The diagrams show the electron arrangement in nitrogen and hydrogen.
Which diagram below, A, B, C or D, represents an ammonia molecule?
Write your answer in the box.
Diagram
(1)
(c)
Ammonia dissolves in water to form a solution with a pH of 10.
What does this pH value tell you about ammonia solution?
........................................................................................................................
(1)
(d)
In industry a large amount of ammonia is neutralised by an acid to make ammonium
nitrate.
(i)
What type of substance is ammonium nitrate?
Tick ( ) one box.
acid
alkali
base
salt
(1)
Page 59 of 95
(ii)
Which acid is added to ammonia to make ammonium nitrate?
Tick ( ) one box.
hydrochloric
citric
nitric
sulfuric
(1)
(iii)
Draw a ring around the main use of ammonium nitrate.
fertiliser
lubricating oil
medicine
plastic
(1)
(e)
Instant cold packs are used to treat sports injuries.
Page 60 of 95
One type of cold pack has a plastic bag containing water. Inside the bag is a smaller bag
containing ammonium nitrate.
The outer bag is squeezed so that the inner bag bursts. The ammonium nitrate dissolves
in the water. This process is endothermic.
Explain why the bag becomes cold.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(2)
(Total 8 marks)
Page 61 of 95
M1.
(a)
oxygen / O2 (do not allow air)
for 1 mark
1
(b)
idea that
(it is a) catalyst / it increases the rate of reaction
for 1 mark
1
(c)
water H2O and oxygen / O2 (need both) (in either order)
for 1 mark
1
(d)
ammonia / NH3 (do not allow ammonium)
(allow ammonium hydroxide / NH4OH or ammonia solution)
nitric acid / NHO3
in any order for 1 mark each
2
(e)
14 + 4 + 14 + 48 or
Mr = 80
gains 1 mark
but
or 35%
gains 2 marks
2
[7]
M2.
(a) lead chloride
} in any order
potassium nitrate }
for 1 mark each
2
(b)
lead chloride is solid / a precipitate
potassium nitrate is aqueous / in solution / dissolves in water
NOT liquid
for 1 mark each
2
(Accept ratio of molecular KNO3 : PbC12 is 2:1 for 2 marks)
(do not accept relative number of atoms in each compound)
One is a solid, one is a solution – worth 1 mark
[4]
Page 62 of 95
M3.
•
correct use of react/reaction/reactants NOT mixed added to join/combine/displace
NOT equals
•
correct use of produce/products/gives/forms/makes/creates
•
reactants correctly identified
•
products correctly identified
(copper oxide reacts with sulphuric acid to produce copper sulphate
and water, will be awarded all 4 marks)
for 1 mark each
Reactants must be correctly identified for ‘react’ mark to be given. Similarly for products
[4]
M4.
(a)
(i)
lead chloride/product of lead + chloride ions is insoluble (in water)
for 1 mark
1
(ii)
Pb2+ + 2C1¯ → PbC12 *(s)
(allow (Pb)2+ 2 (C1–) )
formula
solid state symbol
balancing
for 1 mark each
3
(b)
copper hydroxide Cu(OH)2
each for 1 mark
lead sulphate
PbSO4
each for 1 mark
no precipitate
for 1 mark
Allow 1 mark for correct formula Na2SO4 in (i)
Allow 1 mark for correct formula Mg (NO3)2 in (ii)
0 marks for any formula in (iii)
5
[9]
Page 63 of 95
M5.
(i)
carbon dioxide (allow CO2)
for 1 mark
1
(ii)
sodium nitrate (accept correct formula)
for 1 mark
1
[2]
M6.
(a)
(i)
sodium ions and chloride ions
(allow sodium chloride/salt) [not “chlorine”] for 1 mark
1
(ii)
sodium ions and chloride ions
(allow sodium chloride/salt) for 1 mark
H + ions (allow hydrochloric acid)
for 1 mark
2
(b)
H+ + OH– → H2O
[N.B Na+ and Cl– may also be present]
H+ ions from acid
OH– ions from alkali
each for 1 mark
[N.B First mark lost if changes on ions not shown]
3
[6]
##
(a)
sodium ions and chloride ions (not chlorine)
allow sodium chloride/salt/common salt
for 1 mark
1
(b)
H+ + OH– →H2O
H+ from (hydrochloric) acid
OH- from alkali/sodium hydroxide
lose 1 mark if no charge shown disregard other ions
each for 1 mark
3
[4]
-
Page 64 of 95
M8.
(i)
hydrogen, hydroxide and sulphate
all three and no others
any order
do not credit any formula(e)
1
(ii)
the anode is positive
1
(so) only the negative ions are attracted to it
or (so) only the hydroxide ions and the sulphate ions are attracted
(to it)
or (so) only the anions are attracted (to it)
1
(iii)
2H2O + O2 + 4e–
1
[4]
M9.
(a)
(i)
8
ammonia
do not credit ammonium
sulphuric acid
do not credit just sulphuric; credit sulfuric acid
do not credit hydrogen sulphate
3
(ii)
(as a) fertiliser
1
(iii)
nitric (acid)
accept HNO3 if correct in every detail
1
(b)
(i)
chemical change (in which)
or under suitable conditions
1
product(s) can be converted to reactant(s)
or direction of reaction can be reversed
or equilibrium can be achieved
do not credit reaction can be reversed
1
(ii)
air
or (the) atmosphere
1
Page 65 of 95
(iii)
made of atoms
1
which are all the same
credit the idea that the particles (in an element) are all the same
even if the name of the particles (the first mark) is incorrect
or which have the same number of protons
or which have the same atomic number / proton number
it cannot be broken down into anything simpler (2) marks
1
[10]
M10.
NOTE
In this question and throughout the Paper, if the name of a chemical is
asked for, then the formula is acceptable only if it is correct in every detail.
If the name is correct and the candidate has tried to be ‘helpful’ by giving,
in addition, an incorrect version of the formula, then this is acceptable
provided it does not lead to ambiguity.
(i)
nitric (acid)
accept HN03
1
(ii)
sulphuric (acid)
accept H2SO4
1
(iii)
heat given out
or temperature rise
or energy given out
or steam
do not credit just ‘use a thermometer’
do not credit just 'change in temperature'
1
(iv)
neutralisation
accept neutralise
accept neutral
accept formation of salt or water
do not credit exothermic
1
[4]
M11.
(a)
ammonium nitrate
accept NH4NO3
do not accept ammonia nitrate
1
Page 66 of 95
(b)
different reactions need different catalysts
1
(c)
they are used over and over again
accept they are reused
accept they are not used up
accept they are not changed
recycling is neutral
1
(d)
any two from
they speed up reactions
they reduce energy requirements
accept allow reactions to take place at a lower temperature
they reduce costs
accept make process more economic
2
(e)
(high pressure) increases the
frequency of collisions
accept more collisions
move faster is neutral
1
this increases the rate of reaction
accept ‘more successful collisions’ for 2 marks
1
[7]
M12.
(a)
nitrogen
accept N or N2
1
(b)
the reaction is exothermic
accept the reaction releases heat energy
1
(c)
water
accept H2O or hydrogen oxide
1
(d)
with ammonia and nitric acid
1
neutralisation
accept a correct description of reacting (ammonia and nitric acid)
1
[5]
Page 67 of 95
M13.
(a)
(i)
2 Mg + O2 → 2 MgO
both 2s needed
allow O2 or any correct multiple
1
(ii)
solid
1
gas
1
(b)
MgCl2 / C12Mg
do not accept MG mg mG CL cl cL
ignore charges
1
[4]
M14.
sodium nitrate
1
NaNO3
do not credit lower case N or O, upper case A
1
potassium sulphate
1
K2SO4
accept potassium hydrogen sulphate or
KHSO4
do not credit lower case K, S or O
ignore charges on ions
1
[4]
M15.
(a)
NO2 / 2NO2(g) / Nitrogen dioxide
for one mark
1
(b)
particles of gas move / they move
reject spread out
particles move randomly / mix / go between air molecules / diffusion
any two for 1 mark each
2
(c)
faster reaction / more surface area (not smaller pieces)
for one mark
1
Page 68 of 95
(d)
(i)
either lower temperature / particles move slower
fewer collisions (owtte) / less energetic collisions / owtte
or acid diluted (owtte)
fewer collisions (owtte)
for 1 mark each
2
(ii)
alkali neutralises the acid / stops the reaction
or water will only slow the reaction not stop it
either for 1 mark
1
[7]
M16.
(i)
sulphuric acid / H2SO4
accept sulfuric
1 for one mark
1
(ii)
exothermic
for one mark
1
(iii)
Na2SO4 / (Na)2SO4 / Na2(SO4) / (Na+)2SO42–
for one mark
lower case O(Na2SO4) not accepted / tops of subscripted letters
should be in line or lower than lower case letters of symbols
1
[3]
##
(a)
(2) : (6) : (2)
All 3 correct gains 2 marks
2 correct gains 1 mark
2
(b)
no water present/moist air cannot enter/do not thoroughly mix/
must be in solution etc.
for 1 mark
1
Page 69 of 95
(c)
(i)
hydroxide (ion) / OH–
for 1 mark
1
(ii)
hydrogen (ion) / H+
for 1 mark
1
(iii)
water/H2O/hydrogen oxide
for 1 mark
1
[6]
##
(a)
potassium / K
for 1 mark
1
(b)
carbon dioxide / CO2
for 1 mark
1
(c)
losing
electrons
gaining
electrons
for 1 mark each
4
(d)
(i)
power supply, (not mains)
beaker containing solution,
(inert) electrodes and circuit
ammeter or bulb/
(or see bubbling etc. at electrodes written by drawing)
for 1 mark each
4
(ii)
reading on ammeter/bulb lights / (solution) conducts (electricity)
bubbling / gas produced
hydrogen produced
chlorine / oxygen produced
ions move
to electrodes (must be linked to ions move)
negative ions move to the positive electrode
and/or positive ions move to the negative electrode
negative ions lose electrons
and/or positive ions gain electrons
any 3 for 1 mark each
3
[13]
Page 70 of 95
M19.
(a)
(i)
Na2CO3 or (Na+)2 CO32– must be completely correct
for 1 mark
1
(ii)
(1)
decomposition of limestone
or decomposition of coal
or decomposition of sodium hydrogen carbonate (owtte.)
allow equations even if not
correctly balanced
any 1 for 1 mark
1
(2)
breakdown/split up not decomposed by heat
for 1 mark each
2
(iii)
carbon dioxide or ammonia [CO2] or [NH3]
for 1 mark
1
(b)
(i)
zinc carbonate or zinc hydroxide
allow formulae if completely correct
for 1 mark
1
(ii)
(zinc carbonate) is insoluble (in water)
((i) and (ii) are independent marks)
for 1 mark
1
[7]
M20.
(a)
(i)
hydrogen/H2
for 1 mark
1
(ii)
i.e. 2Cl¯ -2e– →Cl2
for 1 mark
1
(iii)
hydroxide or OH–
for 1 mark
1
(iv)
sodium hydroxide/caustic soda/NaOH/bleach/
chemical name of bleach
for 1 mark
1
Page 71 of 95
(b)
(i)
Na2CO3 or (Na+)2 CO32–
for 1 mark
1
(ii)
coal
water/H2O
limestone/CaCO3/calcium carbonate
any one for 1 mark
1
(iii)
calcium chloride/CaCl2/sodium hydrogen
carbonate/NaHCO3
for 1 mark
1
(iv)
decomposition/heating of limesstone
decomposition/heating of coal
decomposition/heating of sodium
hydrogen carbonate
any 1 for 1 mark
1
described change e.g. NaHCO3 → Na2 CO3
(Use judgement)
breakdown (owtte.)
by heat
for 1 mark each
2
(v)
carbon dioxide/CO2 or ammonia/NH3
for 1 mark
1
(c)
(i)
zinc carbonate/ZnCO3/zinc
hydroxide/Zn(OH)2
for 1 mark
1
(ii)
It is insoluble
zinc carbonate is insoluble in water
for 1 mark
1
[13]
M21.
(a)
(i)
H+ + OH- → H2 O/H3O+ + OH- → 2H2 O
for 1 mark
1
Page 72 of 95
(ii)
1 point from e.g.
smaller bits
bigger surface area
faster reaction
dissolve faster
more particles open to attack by acid
any 1 for 1 mark
1
(iii)
MgCO3 or MG2+CO32- or CO3 Mg
for 1 mark
1
(b)
(i)
2 HCl
for 1 mark
1
(ii)
aqueous/dissolved in water (not in solution)
for 1 mark
1
(iii)
CO2/gas evolved/gas has mass
for 1 mark
1
(c)
(i)
plotting points
scales
curve
labelling axes including units
for 1 mark each
4
(d)
faster
same final mass
for 1 mark each
2
[12]
M22.
(a)
40 + 12 + (3 × 16) = 100
each for 1 mark
2
(b)
Mr of CaO = 56
for 1 mark
mass required = 60 × 100/56
for 2 marks
= 107.1
for 1 mark
4
Page 73 of 95
(c)
(i)
calcium hydroxide
1
(ii)
solid
1
[8]
M23.
(a)
sodium
1
(b)
neutralisation
1
(c)
increase/inc. number
1
(d)
H+
1
(e)
OH–
(f)
H+ + OH– → H2O
1
[6]
M24.
(a)
(i)
fertilisers
for 1 mark
1
(ii)
7
for 1 mark
1
(iii)
5
for 1 mark
(ignore other units)
1
(b)
(i)
both nitrogen and hydrogen
for 1 mark
1
(ii)
two of:
nitrogen;
hydrogen/methane/natural gas;
oxygen/air;
water;
any fuel
(allow symbols, do not allow nitrogen oxides)
any two for 1 mark each
2
Page 74 of 95
(c)
(i)
alkali/alkaline/base/basic
for 1 mark
1
(ii)
must be nitrate
for 1 mark
1
(iii)
thermometer or any other temperature measuring device
for 1 mark
1
[9]
M25.
(a)
(i)
iron must be named
do not accept Fe
1
(ii)
hydrogen
1
and oxygen mixtures
1
burn rapidly
1
(b)
(i)
lowers concentration
accept dilutes the acid
do not accept cooling
1
less collisions (between particles)
1
(ii)
H+ (aq)
accept H3O+ only if 2 in front of H2O
1
OH− (aq)
if spectator ions correctly included on both sides, maximum = 1
mark
1
Page 75 of 95
(iii)
Ca(OH2) weak alkali
accept NaOH strong alkali
1
Ca(OH)2 causes no problems
accept NaOH causes named problem
(eg caustic or exothermic or burns or corrosive)
1
[10]
M26.
(a)
(i)
(s)
(aq)
(1)
2 or 3 correct 1 mark
1 correct 0 marks
(g)
2
(ii)
calcium chloride
1
(b)
(i)
points
deduct 1 mark for each error to a maximum of 2 marks
2
line
accept a single line ‘best fit’ curve
accept reasonable attempt at curve
1
(ii)
increase temperature or heat
accept increase surface area or
increase concentration or description
1
(iii)
75% or ¾
not pure 1 mark
only 60 cm3 (instead of 80 cm3 of gas)
or
× 100 1 mark
3
[10]
Page 76 of 95
M27.
(a)
(i)
H2SO4 or red (acidic) pH < 7
accept names of compounds
accept correct use of acidic
1
NaOH or purple (alkaline) pH > 7
alkaline and neutral without any mention of pH for 1 mark only
1
NaCl or green (neutral) pH 7
ignore high or low pH
1
(ii)
hydrogen (ion)
accept proton
accept hydroxonium ion
1
H+
accept H3O+ for hydroxonium ion
1
(b)
(i)
neutralisation
1
(ii)
NaOH + HCl
ignore state symbols
1
NaCl + H2O
ignore state symbols
maximum of 1 mark if incorrectly balanced
1
(c)
(i)
sodium – 2 . 8 . 1
accept 2.8.1 written
1
chlorine – 2 . 8 . 7
accept 2.8.7 written
1
(ii)
ion(s)
1
(iii)
attraction between oppositely charged particles (ions)
accept attraction between + and – particles (ions)
accept electrostatic attraction
1
Page 77 of 95
(d)
chloride ions lose electrons to form chlorine
Cl– – e– → Cl
1
hydrogen ions gain electrons to form hydrogen
H+ + e– → H
1
sodium hydroxide remains in solution
Na + and OH– remain in solution to form sodium hydroxide
1
[15]
M28.
(a)
(i)
test: limewater
accept calcium hydroxide solution
1
result: ‘goes’ cloudy
accept white or milky
do not accept misty or chalky test must be correct before result
mark can be considered
1
(ii)
2 NaHCO3 + H2SO4 →
Na2SO4 + (2) H2O + (2) CO2
1
correctly balanced
1
(b)
(i)
H+ + OH–
1
→ H2O
deduct one mark if incorrectly balanced
accept H3O+ instead of H+ then 2H2O needed for balance
1
(ii)
pH increases
accept numerical indication
1
Page 78 of 95
(c)
addition of sulphuric acid
1
correct use of an indicator
accept idea of forming a neutral solution
1
crystallisation (of neutral solution)
accept description using evaporation
1
[10]
M29.
(a)
breakdown / decomposition / splits into elements /
not ions
separates into elements / produce a chemical reaction
1
using electricity
1
(b)
lead bromide melted / free ions
not electrolyte
1
(c)
(+) bromine
element must be appropriate to electrode
1
(–) lead
element must be appropriate to electrode
1
(d)
fume cupboard / protective clothing
allow safety glasses
not safety mat
1
[6]
M30.
(i)
Mg + (H2SO4) →
1
MgSO4 +
1
H2
deduct 1 mark if not balanced only if all three correct
accept alternative metal of similar reactivity for example Zn or Fe
candidate would not then be awarded first mark for Mg
then error carried forward
deduct 1 mark if not balanced only if all three correct
1
Page 79 of 95
(ii)
to remove the (excess) magnesium
accept separate
accept insoluble substances or solids or residue
do not accept unreactive substances or impurities or remove
magnesium from sulphuric acid
1
(iii)
to evaporate (some of the water or solution)
1
to form crystals or crystallise
accept to form a saturated solution
or concentrated solution
do not accept to leave MgSO4
1
[6]
M31.
(a)
(i)
calcium
carbonate
→
calcium
oxide
+
carbon
dioxide
accept CaO3 → CaO + CO2
1
(ii)
(thermal) decomposition
accept endothermic
accept reversible
1
(b)
(i)
neutralisation
accept exothermic
1
(ii)
sulphuric (acid) H2SO4
2
(c)
(i)
to speed up the reaction
accept to increase the rate of reaction or to increase the number
or rate of collisions
do not accept “dissolves” copper oxide faster
1
Page 80 of 95
(ii)
all acid reacts
accept there will be no acid left or acid used up
1
acid is neutralised (for 2 marks)
do not accept to form a concentrated or saturated solution
1
(excess) copper oxide collects in filter paper
accept larger particles (of copper oxide) cannot pass through filter
paper
1
copper sulphate solution passes through the filter paper
accept dissolved copper sulphate passes through filter paper or
smaller particles (of copper sulphate) in solution (liquid) pass
through filter paper
accept (black) solid collects in filter paper and filtrate or soluble
solid or (blue) solution (liquid) passes through filter paper for 1
mark only
1
[10]
M32.
(a)
(i)
to remove or separate copper oxide
accept to remove or separate
unreacted or excess base
accept to remove or separate insoluble solids
1
(ii)
heat (the solution)
accept heat the water
accept evaporate the water
rapid cooling/cool to lower temperature
accept boil the water or solution
not increase surface area, put in
draught
not increase the temperature
1
(iii)
aqueous
accept in water
accept solution
not soluble in water
1
Page 81 of 95
(b)
add water/liquid/solution
1
colour changes to blue
1
[5]
hydrogen ions (from acid) or protons / H+
M33.
1
react with hydroxide ions (from alkali) / OH
1
to produce water
H
+ OH
H2O gains all 3 marks
ignore state symbols
molecules of hydrogen ions and molecules of
hydroxide ions produce water = 2 marks
if they fail to get any of the above marks they can
get 1 mark for neutralisation / product neutral
1
[3]
M34.
(i)
to make sure all sulphuric acid reacts or to neutralise the acid or unreacted
sulphuric acid difficult to remove owtte
ignore ‘to maximise the product’
accept otherwise (sulphuric) acid left
1
(ii)
filter(ing) / filtration or described owtte
accept use filter paper
accept centrifuge and decant
do not accept sieve / strain
filter funnel is insufficient
1
(iii)
no more solid / solute can dissolve
or maximum amount of solid owtte
1
at that temperature
accept any link to temperature or any specified temperature
1
(iv)
solubility decreases (as temperature falls) owtte
accept less soluble in cold water answer must be linked to solubility
ignore the extra cannot dissolve
1
Page 82 of 95
(v)
otherwise get anhydrous CuSO4
accept otherwise get white CuSO4
accept do not get hydrated CuSO4
accept could get CuO or
thermal decomposition / decomposes
allow SO3 / SO2 produced
allow dehydration
accept removes the water of crystallisation
not just remove water from the crystals or just steam
1
[6]
M35.
(a)
(i)
water
accept H2O
accept correct ringed answer in box
1
(ii)
neutralisation
accept underlining or any indication, eg tick
1
(b)
sodium hydroxide
1
sulphuric acid
apply list principletotal
1
[4]
M36.
(a) all lead nitrate reacted
or no lead nitrate left
or enough KI to react with lead nitrate
or to remove all the lead ions
or to get maximum amount of I2
ignore comments about speed
do not accept to remove all the lead
1
(b)
precipitate
allow phonetic spelling
do not accept ppt
1
1
Page 83 of 95
(c)
filter / filtration / centrifuge / decant
do not accept sieve
(d)
any one from:
•
removes (soluble) impurities
•
removes (unreacted) KI
•
removes KNO3
•
removes (excess) solution
•
removes nitrates
purifying is insufficient
do not accept removes potassium
do not accept removes iodide
1
(e)
answer based on filter paper, desiccator, suitable solvent
(gentle) heat, drying cabinet, oven etc.
Accept any method of heating i.e.
bunsen / hairdryer etc.
Accept leave to evaporate / stand or leave in a warm room
e.g. place between dry filter paper, allow to dry
e.g. use propanone, allow to dry
e.g. leave on sunny window sill
e.g. leave in a draught
the answer leave / evaporate /
draught alone is insufficient
1
(f)
wear gloves / mask
or fume-cupboard
or wash hands afterwards
ignore goggles / labcoat or extractor fan / do not touch etc.
1
[6]
M37.
nitric acid
1
potassium hydroxide
1
water
1
[3]
Page 84 of 95
M38.
(a)
H+(aq) + OH– (aq) → H2O(l) or
H3O+(aq) + OH–(aq) → H2O(l)
mark for correct equation
mark for state symbols
any other symbols = 0 marks
accept correct spectator ions e.g.
Na+(aq) + OH– (aq) + H+(aq) + Cl– (aq) → Na+(aq) + Cl– (aq)
+ H2O(l)
2
(b)
(i)
nitric acid and ammonia (solution)
HNO3
NH3 / NH4OH
mark for both
accept ammonium hydroxide /
NH4OH instead of ammonia
do not accept ammonia hydroxide
do not accept hydrogen nitrate solution
accept correct formulae
1
(ii)
provides oxygen or oxidising (agent) or oxidant
do not accept it contains oxygen alone
or rich in oxygen
1
[4]
M39.
(i)
potassium hydroxide
accept correct formulae
1
water
1
(ii)
fertiliser
1
(iii)
H+
accept hydrogen but not H
1
[4]
M40.
(a)
(i)
sulfuric
accept H2SO4
accept sulphuric
allow phonetic spellings
1
Page 85 of 95
(ii)
CuO + H2SO4 → CuSO4 + H2O
1 mark for reactants
1 mark for products
ignore state symbols
max 1 mark for incorrect balancing
2
(b)
any two from:
•
particles gain energy or particles have more energy
allow have more activation energy
•
particles move faster
allow they collide faster / quicker
ignore move / vibrate more
•
collide more often
allow more collisions
•
collide more energetically
•
more of the collisions are successful
or more particles have the activation energy
NB more successful collisions alone = 1 mark
if particles are identified as electrons = max 1 mark
2
[5]
M41.
(a)
(i)
(phosphoric) acid
allow phosphoric acid
1
(ii)
hydrogen
1
(b)
(i)
faster / quicker / speeds it up (owtte)
allow answers based on activation energy
ignore helps it to react
1
(ii)
most of the starting materials end up as useful products
1
(iii)
H2O
allow HOH or OH2
1
[5]
Page 86 of 95
M42.
(a)
Compound A
any one from:
accept correct formulae
•
sodium bromide
•
potassium bromide
•
ammonium bromide
•
hydrogen bromide
•
any metal bromide except silver and lead.
1
Compound B
silver nitrate
accept silver sulphate
1
(b)
the silver compound will decompose / silver ions be reduced to silver (owtte)
accept film would darken owtte
accept any idea of light changing silver bromide / silver ions / silver
nitrate / silver sulphate
allow ‘forms a black solid’ / it would turn black
1
(c)
precipitation
accept descriptions of precipitation reactions
accept double decomposition
accept precipitate
do not allow displacement
1
(d)
electrons
1
are gained
the second mark must be linked to electrons
accept it / silver / silver ions gains electrons for both marks
ignore references to oxygen
1
[6]
M43.
(a)
2Mg + O2 → 2MgO
accept correct multiples / fractions
1
Page 87 of 95
(b)
electrons do not need to be paired
accept dots / circles / e instead of crosses
do not allow 2.6 without diagram
1
(c)
electrons do not need to be paired
allow without bracket s/ must have the charge
accept dots / circles / e instead of crosses
ignore extra empty outer shells
ignore nucleus
do not allow [2.8]2+ without diagram
1
(d)
oppositely charged (ions / atoms)
allow positive and negative(ions / atoms)
1
(they) attract
must be in correct context
accept held by electrostatic forces
ignore ionic bonding
maximum 1 if they refer to intermolecular forces / attractions /
covalent bonds
1
(e)
magnesium chloride
accept MgCl2 (if correctly written)
1
[6]
Page 88 of 95
M44.
(a)
gives out (heat)
1
(b)
D
1
(c)
L
1
(d)
magnesium chloride
1
[4]
M45.
(a)
(i)
any one from:
•
they are positive / cations
•
they are H+
•
opposite charges attract
ignore atom
1
(ii)
potassium is more reactive (or reverse)
assume ‘it’ refers to hydrogen
allow potassium reacts with water
allow potassium is very reactive or most reactive metal / element
allow hydrogen gains electrons more easily / is reduced more
easily
accept potassium is higher up the reactivity series
1
(b)
6 and 2
accept correct multiples and fractions
1
(c)
(i)
the reaction / it is reversible or a description of a reversible reaction
allow ‘it is an equilibrium’
allow reversible symbol drawn correctly
allow ‘the reverse / back reaction’
1
Page 89 of 95
(ii)
lithium nitride
assume that ‘it’ or if they do not specify means lithium nitride
assume lithium / lithium nitrate refers to lithium nitride
•
hydrogen is bonded / held / absorbed / has formed a
compound / reacted with lithium nitride
1
plus one of:
•
does not explode / cause a fire
•
is not free / less hydrogen
•
is not under pressure
•
does not leak
•
is only released slowly
1
•
compound of hydrogen with lithium nitride / product is
(more) stable / less reactive / less chance of a reaction
accept converse for hydrogen as below
assume that gas / hydrogen means gas in the cylinder
•
hydrogen (in cylinder) / gas is not bonded / held
absorbed / in a compound / reacted with lithium
nitride
1
plus one of:
•
can explode / cause a fire
•
is free
•
is under pressure
•
can leak
•
releases quickly
1
(d)
(i)
loss of an electron or loses electrons
do not accept any ref. to oxygen
1
(ii)
full outer shell of 8 electrons on circle
need not be paired
can be ×, dot or e
do not accept if extra electrons added to inner shell
1
[10]
Page 90 of 95
M46.
(a)
water / H2O / hydrogen oxide
1
(b)
eg H (atom) loses an electron to form H+
or only a proton left
1
(c)
is partially ionised in water
1
(d)
(i)
eg same concentration / quantity of Mg
accept: volume of acid / ribbon for both / same time
accept: volume of gas measured under the same conditions
1
(ii)
CADB
1
(e)
(i)
OH–
1
(ii)
acidic
1
[7]
M47.
(a)
one nitrogen atom joined to three hydrogen atoms
1
correct pairs of electrons
1
(b)
because ammonia is made of small molecules / simple
molecules / simple molecular structures
1
and so there are weak forces between the molecules
or and so the intermolecular forces are weak
1
incomplete answers that link only size of molecule or strength of
intermolecular forces with boiling point only gain 1 mark
(c)
(i)
hydroxide
1
(ii)
nitric
1
Page 91 of 95
(d)
because this is an endothermic reaction
1
that takes in energy from the surroundings as the ammonium
nitrate dissolves
1
[8]
M48.
(a)
3
accept correct multiples
1
(b)
sodium hydroxide / potassium hydroxide / alkali / a hydroxide
1
(c)
the chromium ions form a precipitate which can be removed by filtration
accept the chromium ions form a solid which can be removed by
filtration
1
[3]
M49.
Marks awarded for this answer will be determined by the Quality of Written
Communication (QWC) as well as the standard of the scientific response.
No relevant content.
0 marks
There is a brief description of the method or a risk assessment.
Level 1 (1–2 marks)
There is some description of the method that may include a risk
assessment.
Level 2 (3–4 marks)
There is a clear, balanced and detailed description of the method
and a risk assessment.
Level 3 (5–6 marks)
Page 92 of 95
examples of the chemistry points made in the response
The underlined words are needed to gain each bullet point.
•
sulfuric acid is heated in a beaker and copper oxide is added with stirring
•
until the copper oxide is in excess
•
the mixture is filtered
or
the mixture is poured through a funnel and filter paper
•
to remove the excess copper oxide
•
some of the solution is evaporated
or
heated in an evaporating basin/dish
•
the solution is allowed to crystallise / cool down
examples of the risk assessment points made in the response
•
wear safety goggles – to protect eyes because sulfuric acid is corrosive / an irritant
•
care when heating – to protect against burns
•
wash hands after the preparation – copper sulfate is harmful
•
care when handling glass apparatus – to protect against cuts
[6]
M50.
(a)
a solid / insoluble salt is formed
accept salt / substance that does not dissolve forms
1
(b)
hydroxide
1
(c)
filtration
1
(d)
risk is that chromium ions are toxic or harmful
1
[4]
M51.
(a)
4
1
(b)
A
1
Page 93 of 95
(c)
it is alkaline
accept alkali / basic / base
1
(d)
(i)
salt
1
(ii)
nitric
1
(ii)
fertiliser
1
(e)
because energy
1
is taken in (from the surroundings)
second mark must be linked to energy
1
[8]
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Page 95 of 95