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Structure and Bonding-P1
Question Paper
Level
Subject
Exam Board
Unit
Topic
Difficulty Level
Booklet
Time Allowed:
GCSE
Chemistry
AQA
C2
Structure and Bonding-P1
Gold Level
Question Paper
215 minutes
Score:
/215
Percentage:
/100
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Q1.This question is about sodium chloride and iodine.
(a)
Describe the structure and bonding in sodium chloride.
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(4)
(b)
When sodium chloride solution is electrolysed, one product is chlorine.
Name the two other products from the electrolysis of sodium chloride solution.
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(2)
(c)
Many people do not have enough iodine in their diet.
Sodium chloride is added to many types of food. Some scientists recommend that
sodium chloride should have a compound of iodine added.
Give one ethical reason why a compound of iodine should not be added to sodium
chloride used in food.
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(1)
(d)
The bonding in iodine is similar to the bonding in chlorine.
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(i)
Complete the diagram below to show the bonding in iodine.
Show the outer electrons only.
(2)
(ii)
Explain why iodine has a low melting point.
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(3)
(iii)
Explain, in terms of particles, why liquid iodine does not conduct electricity.
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(2)
(Total 14 marks)
Q2.Magnesium oxide nanoparticles can kill bacteria.
The figure below shows the percentage of bacteria killed by different sized nanoparticles.
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Size of nanoparticles in nanometres
(a)
(i)
Give two conclusions that can be made from the figure above.
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(2)
(ii)
Points are plotted for only some sizes of nanoparticles.
Would collecting and plotting data for more sizes of nanoparticles improve the
conclusions?
Give a reason for your answer.
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(1)
(b)
Magnesium oxide contains magnesium ions (Mg2+) and oxide ions (O2–).
Describe, as fully as you can, what happens when magnesium atoms react with
oxygen atoms to produce magnesium oxide.
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(4)
(Total 7 marks)
Q3.Glass is made from silicon dioxide.
© Velirina/iStock/Thinkstock
(a)
Silicon dioxide has a very high melting point.
Other substances are added to silicon dioxide to make glass. Glass melts at a lower
temperature than silicon dioxide.
Suggest why.
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(1)
(b)
Sodium oxide is one of the substances added to silicon dioxide to make glass.
(i)
Sodium oxide contains Na+ ions and O2– ions.
Give the formula of sodium oxide.
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(1)
(ii)
Sodium oxide is made by heating sodium metal in oxygen gas.
Complete the diagram to show the outer electrons in an oxygen molecule (O2).
(2)
(c)
Glass can be coloured using tiny particles of gold. Gold is a metal.
Describe the structure of a metal.
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(3)
(Total 7 marks)
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Q4.Kelp is a seaweed.
Kelp can be used in foods and as a renewable energy source.
© Ethan Daniels/Shutterstock
(a)
Scientific experiments, on their own, cannot fully answer one of the following
questions. Which one?
Tick (
) one box.
Questions
Tick (
)
How much carbon dioxide is produced when 100 g of kelp is burned?
Does kelp give out more heat energy than coal?
Will kelp last longer than coal as an energy source?
Which fuel, kelp or coal, produces the most ash when burned?
(1)
(b)
Scientists cannot answer the question ‘should people use kelp instead of coal as an
energy source?’
Give two reasons why.
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(2)
(c)
Sodium iodide can be produced from kelp.
(i)
How many electrons are in the outer shell of an iodine atom?
(1)
(ii)
Sodium iodide contains sodium ions (Na+) and iodide ions (I–).
Describe, as fully as you can, what happens when sodium atoms react with
iodine atoms to produce sodium iodide.
You may use a diagram in your answer
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(3)
(iii)
The diagram shows the structure of sodium iodide.
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Solid sodium iodide does not conduct electricity.
Why does sodium iodide solution conduct electricity?
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(1)
(iv)
When sodium iodide solution is electrolysed, iodine is formed at the positive
electrode.
Complete and balance the half equation for the formation of iodine.
..........I−
→
I2
+
..........e−
(1)
(v)
What is formed at the negative electrode when sodium iodide solution is
electrolysed?
Explain why.
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(2)
(Total 11 marks)
Q5.The picture shows a copper kettle being heated on a camping stove.
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Copper is a good material for making a kettle because:
•
it has a high melting point
•
it is a very good conductor of heat.
(a)
Explain why copper, like many other metals, has a high melting point.
Your answer should describe the structure and bonding of a metal.
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(4)
(b)
Aeroplanes contain many miles of electrical wiring made from copper. This adds to
the mass of the aeroplane.
It has been suggested that the electrical wiring made from copper could be replaced
by carbon nanotubes which are less dense than copper.
The diagram shows the structure of a carbon nanotube.
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(i)
What does the term ‘nano’ tell you about the carbon nanotubes?
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(1)
(ii)
Like graphite, each carbon atom in the carbon nanotube is joined to three
other carbon atoms.
Explain why the carbon nanotube can conduct electricity.
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(2)
(Total 7 marks)
Q6.This question is about some compounds made from iodine.
(a)
Lead iodide can be made by mixing a solution containing lead ions with a solution
containing iodide ions. Lead iodide is formed as a precipitate.
Pb2+(aq)
+
2I─(aq)
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(s)
The table below gives information about the solubility of some compounds.
Soluble compounds
Insoluble compounds
All sodium and potassium salts
All nitrates
Most chlorides, bromides and iodides
Silver and lead chlorides, bromides
and iodides
Use the table to help you to name:
(i)
A soluble compound which contains lead ions ..................................................
(1)
(ii)
A soluble compound which contains iodide ions .................................................
(1)
(b)
Magnesium iodide can be made by reacting magnesium with iodine.
Mg
+
I2
MgI2
Magnesium iodide is an ionic compound. It contains magnesium ions (Mg2+ ) and
iodide ions (I─).
Describe, in terms of electrons, what happens when magnesium reacts with iodine.
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(4)
(c)
The diagram shows the structure of potassium iodide.
Explain why a high temperature is needed to melt potassium iodide.
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(3)
(Total 9 marks)
Q7.Ammonia is produced from nitrogen and hydrogen.
The equation for this reaction is:
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(a)
(i)
A company wants to make 6.8 tonnes of ammonia.
Calculate the mass of nitrogen needed.
Relative atomic masses (Ar): H = 1; N = 14
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Mass of nitrogen = .......................................... tonnes
(3)
(ii)
The company expected to make 6.8 tonnes of ammonia.
The yield of ammonia was only 4.2 tonnes.
Calculate the percentage yield of ammonia.
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Percentage yield of ammonia = ................................ %
(2)
(iii)
Use the equation above to explain why the percentage yield of ammonia was
less than expected.
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(1)
(b)
Complete the diagram to show the arrangement of the outer shell electrons of the
nitrogen and hydrogen atoms in ammonia.
Use dots (●) and crosses (x) to represent the electrons.
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(2)
(c)
Ammonia dissolves in water to produce an alkaline solution.
(i)
Which ion makes ammonia solution alkaline?
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(1)
(ii)
Name the type of reaction between aqueous ammonia solution and an acid.
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(1)
(iii)
Name the acid needed to produce ammonium nitrate.
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(1)
(iv)
The reaction of ammonia with sulfuric acid produces ammonium sulfate.
Use the formulae of the ions on the Chemistry Data Sheet.
Write the formula of ammonium sulfate.
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(1)
(Total 12 marks)
Q8.This question is about potassium.
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(a)
Humphrey Davy was a professor of chemistry.
In 1807 Davy did an electrolysis experiment to produce potassium.
(i)
Davy first tried to electrolyse a solid potassium salt to produce potassium.
Explain why this electrolysis did not work.
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(2)
(ii)
Humphrey Davy was the first person to produce potassium.
Humphrey Davy’s experiment to produce this new element was quickly
accepted by other scientists.
Suggest why.
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(1)
(b)
A student dissolved some potassium chloride in water. The student tried to
electrolyse the potassium chloride solution to produce potassium.
The apparatus the student used is shown in the diagram.
The student expected to see potassium metal at the negative electrode, but instead
saw bubbles of a gas.
•
Name the gas produced at the negative electrode.
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•
Explain why this gas was produced at the negative electrode and why
potassium was not produced.
The reactivity series of metals on the Chemistry Data Sheet may help you to answer
this question.
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(3)
(c)
The student tried to electrolyse molten potassium chloride to produce potassium.
(i)
Potassium metal was produced at the negative electrode.
Describe how potassium atoms are formed from potassium ions.
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(2)
(ii)
Complete and balance the equation for the reaction at the positive electrode.
...........Cl−
Cl2
+
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(1)
(iii)
Complete the diagram to show the electronic structure of a chloride ion (Cl−).
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(1)
(Total 10 marks)
Q9.
The diagram shows how a heat sink is placed on top of a processor in a computer.
The heat sink is a large piece of metal which conducts heat away from the processor.
If the processor gets too hot it may be damaged.
(a)
(i)
Describe the structure of a metal.
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(3)
(ii)
Why are metals very good conductors of heat?
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(1)
(b)
When viewed under a microscope, it can be seen that the surfaces of the processor
and the heat sink that are in contact are not flat.
There are lots of tiny gaps between the two surfaces.
The gaps contain air, which does not conduct heat very well.
Thermal grease is used to fill the gaps between the processor and the heat sink to
improve the transfer of heat from the processor to the heat sink.
One type of thermal grease contains nanosized particles of silver.
The manufacturer claims that the nanosized particles help to transfer heat better
than normal sized particles.
(i)
How are nanosized particles different from normal sized particles?
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(1)
(ii)
Suggest one reason why nanosized particles of silver might help to transfer
heat better than normal sized particles.
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(1)
(Total 6 marks)
Q10.
Scientists have recently developed a method to produce large sheets of a substance
called graphene.
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Graphene is made from carbon and is a single layer of graphite just one atom thick.
The properties of graphene include:
•
it conducts electricity
•
it is transparent since it is only one
atom thick
•
it is strong and durable.
These properties make it suitable to
overlay a monitor screen to make it a
touchscreen.
The photograph below shows the structure of graphene.
Photographs supplied by iStockphoto/Thinkstock
Use your knowledge of the bonding in graphite and the photograph of the structure to help
you to explain, as fully as you can:
(a)
(i)
why graphene is strong;
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(3)
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(ii)
why graphene conducts electricity.
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(2)
(b)
Suggest why a sheet of graphite which has a large number of carbon layers would
not be suitable for the touchscreen.
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(1)
(Total 6 marks)
Q11.
This question is about gold (Au).
(a)
An atom of gold is represented as:
197
Au
79
How many neutrons are in this atom of gold? ...............................................
(1)
(b)
Gold ions are used as a catalyst.
How does a gold atom (Au) become a gold ion (Au3+)?
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(2)
(c)
A gold catalyst can be used when carbon monoxide reacts with oxygen to make
carbon dioxide.
(i)
Complete and balance the equation for this reaction.
.... CO
+
..............
→
..... CO2
(2)
(ii)
Carbon dioxide has a very low boiling point.
Explain why.
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(3)
(d)
Gold is used as a catalyst in industrial processes. Gold is rare and increasingly
expensive.
Suggest three reasons why gold is still used in industrial processes.
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(3)
(Total 11 marks)
Q12.
This question is about calcium hydroxide.
Ancient artworks and monuments can be protected from acid rain if the surface is sprayed
with calcium hydroxide nanoparticles.
By Svilen Enev (Own work) [GFDL or CC-BY-SA-3.0], via Wikimedia Commons
(a)
Calcium hydroxide has the formula Ca(OH)2
Why are there two hydroxide ions for each calcium ion in the formula?
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(1)
(b)
The calcium hydroxide is used in the form of nanoparticles.
What are nanoparticles?
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(1)
(c)
A student added water to calcium oxide to make calcium hydroxide.
The equation for the reaction is shown below.
CaO +
H2O →
Ca(OH)2
Calculate the maximum mass of calcium hydroxide which could be made from 2.00
g of calcium oxide.
Relative atomic masses (Ar): H = 1; O = 16; Ca = 40.
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Maximum mass of calcium hydroxide = ............................... g
(3)
(Total 5 marks)
Q13.
Graphite and diamond are different forms of the element carbon.
Graphite and diamond have different properties.
The structures of graphite and diamond are shown below.
Graphite
Diamond
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(a)
Graphite is softer than diamond.
Explain why.
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(4)
(b)
Graphite conducts electricity, but diamond does not.
Explain why.
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(3)
(Total 7 marks)
Q14.
Diamonds are used as abrasives.
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Model of part of the diamond structure
Diamonds are very hard.
Explain why.
A good answer will include information on the structure and bonding in diamonds.
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(3)
(Total 3 marks)
Q15.
High quality connectors are used to connect a satellite box to a television.
The connectors should conduct electricity very well and should not corrode.
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By Alphathon (Own work) [CC-BY-SA-3.0 or GFDL], via Wikimedia Commons
The connectors on this scart lead are coated with gold.
(a)
Gold is a typical metal.
(i)
Describe the structure and bonding of gold.
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(3)
(ii)
Why is gold a good conductor of electricity?
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(1)
(b)
The surface of some metals, such as iron, corrode when exposed to the air.
Suggest why this reduces the electrical conductivity of the metal.
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(2)
(Total 6 marks)
Q16.
Welding blankets are placed under metals being welded. They protect the area
under the welding.
Some welding blankets are made from silicon dioxide which does not melt when hit by
sparks or molten metal.
The diagram shows a small part of the structure of silicon dioxide.
Describe the structure and bonding in silicon dioxide and explain why it is a suitable
material for making welding blankets.
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(3)
(Total 3 marks)
Q17.
Lead compounds have been used for thousands of years as colours in paint.
Johannes Vermeer [Public domain], via Wikimedia Commons
(a)
A sample of a red oxide used in paint was found to contain 6.21 g of lead and 0.64
g of oxygen.
Calculate the empirical (simplest) formula of this compound.
You must show all your working to gain full marks.
Relative atomic masses: O = 16; Pb = 207.
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(4)
(b)
A problem with lead compounds is that they slowly react with hydrogen sulfide in
the air. This produces lead sulfide which is black.
(i)
Hydrogen sulfide has the formula H2S. The bonding in a molecule of hydrogen
sulfide can be represented as:
H–S–H
Complete the diagram below to show the arrangement of the outer electrons
of the hydrogen and sulfur atoms in hydrogen sulfide.
Use dots (●) and crosses (x) to represent the electrons.
You need only show the outer shell electrons.
(Atomic numbers: H = 1; S = 16.)
(1)
(ii)
Hydrogen sulfide has a low boiling point.
Explain why.
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(2)
(iii)
Lead white is also used in paint. The white colour slowly darkens when lead
sulfide is produced.
The painting can be restored with hydrogen peroxide. This converts the black
lead sulfide into white lead sulfate.
Balance the equation for the reaction between lead sulfide and hydrogen
peroxide (H2O2).
PbS(s) +
............H2O2(aq)
→ PbSO4(s)
+ 4H2O(l)
(1)
(Total 8 marks)
Q18.
The picture shows a copper kettle being heated on a camping stove.
Copper is a good material for making a kettle because:
•
it has a high melting point
•
it is a very good conductor of heat.
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(a)
Explain why copper, like many other metals, has a high melting point.
You should describe the structure and bonding of a metal in your answer.
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(4)
(b)
An aeroplane contains many miles of electrical wiring made from copper. This adds
to the mass of the aeroplane.
It has been suggested that the electrical wiring made from copper could be replaced
by lighter carbon nanotubes.
The diagram shows the structure of a carbon nanotube.
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(i)
What does the term ‘nano’ tell you about the carbon nanotubes?
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(1)
(ii)
Like graphite, each carbon atom is joined to three other carbon atoms.
Explain why the carbon nanotube can conduct electricity.
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(2)
(Total 7 marks)
Q19.
This question is about some compounds of iodine.
(a)
Lead iodide can be made by mixing a solution containing lead ions with a solution
containing iodide ions.
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Lead iodide is formed as a precipitate.
Pb2+(aq)
(i)
+
2l–(aq)
→
Pbl2(s)
The table below gives information about the solubility of some compounds.
Soluble compounds
Insoluble compounds
all sodium and potassium salts
all nitrates
most chlorides, bromides and iodides
silver and lead chlorides, bromides and
iodides
Use the table to help you name:
a soluble compound which contains lead ions ......................................
a soluble compound which contains iodide ions ...................................
(2)
(ii)
Suggest a method of separating the lead iodide from the solution.
...............................................................................................................
(1)
(b)
Magnesium iodide can be made by reacting magnesium with iodine.
Mg
+
I2
→
MgI2
Magnesium iodide is an ionic compound. It contains magnesium ions (Mg2+) and
iodide ions (I-).
Describe, in terms of electrons, what happens when magnesium reacts with iodine.
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.........................................................................................................................
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.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
.........................................................................................................................
(4)
(c)
The diagram shows the structure of potassium iodide.
Explain why a high temperature is needed to melt potassium iodide.
.........................................................................................................................
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.........................................................................................................................
(2)
(Total 9 marks)
Q20.
Ammonia has the formula NH3
The diagrams show how electrons are arranged in nitrogen and hydrogen atoms.
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(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)
(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.
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(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.
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)
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(Total 8 marks)
Q21.
This drinks bottle is made of thermosoftening plastic.
Drinks bottles of this type can be recycled.
Describe and explain how the bottles can be changed into new plastic objects.
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(Total 4 marks)
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Q22.
The picture shows sodium reacting with chlorine.
The reaction forms sodium chloride, which contains sodium ions and chloride ions.
(a)
The diagrams show how electrons are arranged in a sodium atom and a chlorine
atom.
Explain, in terms of electrons, what happens when sodium reacts with chlorine.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
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(b)
Explain, as fully as you can, why sodium chloride has a high melting point.
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
........................................................................................................................
(3)
(Total 6 marks)
Q23.
This barbecue burns propane gas.
The structure of propane is shown below.
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(a)
Complete the diagram to show how the outer energy level (shell) electrons of
hydrogen and carbon are arranged in a molecule of propane.
(1)
(b)
The graph shows how the vapour pressure of propane changes with temperature.
The vapour pressure of a liquid is the pressure of the vapour above the liquid.
(i)
Describe, as fully as you can, how the vapour pressure of propane changes
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with temperature.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(2)
(ii)
The boiling point of a liquid is the temperature at which its vapour pressure is
equal to the air pressure above the liquid.
Use the graph to find the boiling point of propane when the air pressure is 100
kilopascals.
Boiling point ................................................... °C
(1)
(c)
Explain, in terms of molecules, why propane has a low boiling point.
.....................................................................................................................................
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(2)
(Total 6 marks)
Q24.
Aspirin tablets have important medical uses.
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A student carried out an experiment to make aspirin. The method is given below.
1.
2.
3.
4.
5.
6.
7.
8.
Weigh 2.00 g of salicylic acid.
Add 4 cm3 of ethanoic anhydride (an excess).
Add 5 drops of concentrated sulfuric acid.
Warm the mixture for 15 minutes.
Add ice cold water to remove the excess ethanoic anhydride.
Cool the mixture until a precipitate of aspirin is formed.
Collect the precipitate and wash it with cold water.
The precipitate of aspirin is dried and weighed.
(a)
The equation for this reaction is shown below.
C7H6O3
+
salicylic acid
C4H6O3
→
C9H8O4
aspirin
+
CH3COOH
Calculate the maximum mass of aspirin that could be made from 2.00 g of salicylic
acid.
The relative formula mass (Mr) of salicylic acid, C7H6O3, is 138
The relative formula mass (Mr) of aspirin, C9H8O4, is 180
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
Maximum mass of aspirin = .............................. g
(2)
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(b)
The student made 1.10 g of aspirin from 2.00 g of salicylic acid.
Calculate the percentage yield of aspirin for this experiment.
(If you did not answer part (a), assume that the maximum mass of aspirin that can
be made from 2.00 g of salicylic acid is 2.50 g. This is not the correct answer to part
(a).)
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
.....................................................................................................................................
Percentage yield of aspirin = .............................. %
(2)
(c)
Suggest one possible reason why this method does not give the maximum amount
of aspirin.
.....................................................................................................................................
.....................................................................................................................................
(1)
(d)
Concentrated sulfuric acid is a catalyst in this reaction.
Suggest how the use of a catalyst might reduce costs in the industrial production of
aspirin.
.....................................................................................................................................
.....................................................................................................................................
(1)
(Total 6 marks)
Q25.
This drill contains an electric motor.
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The diagram below shows the main parts of an electric motor.
The carbon contacts are made of graphite. Springs push the contacts against the copper
ring.
The contacts conduct electricity to the copper ring. The copper ring rotates rapidly but
does not stick or become worn because the graphite is soft and slippery.
Graphite has properties which are ideal for making the contacts in an electric motor.
Explain, in terms of structure and bonding, why graphite has these properties.
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...............................................................................................................................................
...............................................................................................................................................
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...............................................................................................................................................
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(Total 5 marks)
Q26.
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.
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(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)
(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
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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)
(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)
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Q27.
Perfumes contain a mixture of chemicals.
The main ingredients of perfumes are a solvent and a mixture of fragrances.
(a)
A sample of the solvent used in one perfume contained 0.60 g of carbon, 0.15 g of
hydrogen and 0.40 g of oxygen.
Relative atomic masses: H = l; C = 12; O = 16.
Calculate the empirical (simplest) formula of the solvent.
You must show all of your working to gain full marks for this question.
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.....................................................................................................................................
(4)
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(b)
Solvent molecules evaporate easily.
Explain why substances made of simple molecules evaporate easily.
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(2)
(c)
Most companies claim that their perfumes have been tested on skin. A study was
made of the tests they used. The study found that each company used different
tests.
The perfumes were tested in the companies’ own laboratories and not by
independent scientists.
Some companies did not give any information about the tests that they had used.
(i)
Suggest why companies test their perfumes on skin.
...........................................................................................................................
...........................................................................................................................
...........................................................................................................................
(1)
(ii)
Did the study show that the tests made by the different companies were valid
and reliable?
Explain your answer.
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...........................................................................................................................
...........................................................................................................................
(2)
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(Total 9 marks)
Q28.
(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.
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(1)
(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)
Q29.
Bricks made from silica (silicon dioxide) are used to line furnaces that operate at
high temperatures.
Part of the structure of silica is shown in the diagram.
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Suggest and explain why silica is used to make bricks for high-temperature furnaces. In
your answer, you should refer to the structure of, and bonding in, silica.
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(Total 4 marks)
Q30.
Read the article about the use of nanoparticles in sun creams.
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Sun creams
Many sun creams use nanoparticles. These sun creams are very good at
absorbing radiation, especially ultraviolet radiation. Owing to the particle size, the
sun creams spread more easily, cover better and save money because you use
less. The new sun creams are also transparent, unlike traditional sun creams
which are white. The use of nanoparticles is so successful that they are now used
in more than 300 sun cream products.
Some sun creams contain nanoparticles of titanium oxide. Normal-sized particles
of titanium oxide are safe to put on the skin.
It is thought that nanoparticles can pass through the skin and travel around the
body more easily than normal-sized particles. It is also thought that nanoparticles
might be toxic to some types of cell, such as skin, bone, brain and liver cells.
(a)
Explain why nanoparticles pass through the skin and travel around the body more
easily than normal-sized particles of titanium oxide.
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
....................................................................................................................................
(2)
(b)
Explain why sun creams containing nanoparticles should be tested further.
....................................................................................................................................
....................................................................................................................................
(1)
(c)
Suggest why some companies that make sun creams might not want to do more
tests.
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....................................................................................................................................
....................................................................................................................................
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....................................................................................................................................
(2)
(Total 5 marks)
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