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Question
AQA Level 1/2 Certificate
June 2013
Chemistry
1
2
8402/2
3
4
5
Paper 2
Monday 10 June 2013
Mark
6
1.30 pm to 3.00 pm
TOTAL
For this paper you must have:
 a ruler
 a calculator
 the periodic table (enclosed).
Time allowed
 1 hour 30 minutes
Instructions
 Use black ink or black ball-point pen.
 Fill in the boxes at the top of this page.
 Answer all questions.
 You must answer the questions in the spaces provided. Do not write
outside the box around each page or on blank pages.
 Do all rough work in this book. Cross through any work you do not want
to be marked.
Information
 The marks for questions are shown in brackets.
 The maximum mark for this paper is 90.
 You are expected to use a calculator where appropriate.
 You are reminded of the need for good English and clear presentation in
your answers.
 Question 3(d) should be answered in continuous prose.
In this question you will be marked on your ability to:
– use good English
– organise information clearly
– use specialist vocabulary where appropriate.
Advice
 In all calculations, show clearly how you work out your answer.
(Jun138402201)
G/T94288
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8402/2
2
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Answer all questions in the spaces provided.
1
Saturated hydrocarbons, for example methane and octane, are often used as fuels.
1 (a)
Methane can be represented as:
H
H
C
H
H
1 (a) (i)
The formula of methane is ............................................... .
(1 mark)
1 (a) (ii) Draw a ring around the correct answer to complete the sentence.
double.
In a saturated hydrocarbon molecule all of the bonds are
ionic.
single.
(1 mark)
1 (a) (iii) Draw a ring around the correct answer to complete the sentence.
alcohols.
The homologous series that contains methane and octane is called the
alkanes.
alkenes.
(1 mark)
1 (b) (i)
The complete combustion of petrol produces carbon dioxide, water vapour and
sulfur dioxide.
Name three elements petrol must contain.
1 .........................................................................................................................................
2 .........................................................................................................................................
3 .........................................................................................................................................
(3 marks)
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1 (b) (ii) The exhaust gases from cars can contain oxides of nitrogen.
Complete the sentence.
Nitrogen in the oxides of nitrogen comes from ................................................................ .
(1 mark)
1 (b) (iii) The sulfur dioxide and oxides of nitrogen from cars cause an environmental problem.
Name the problem and describe one effect of the problem.
Name of problem ...............................................................................................................
Effect of problem ...............................................................................................................
............................................................................................................................................
(2 marks)
1 (c)
When a fuel burns without enough oxygen, there is incomplete combustion.
One gaseous product of incomplete combustion is carbon monoxide.
Name one solid product of incomplete combustion.
................................................................................
(1 mark)
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1 (d)
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A student investigated how well different hydrocarbon fuels would heat up 100 g of
water.
Her hypothesis was:
The more carbon atoms there are in a molecule of any fuel, the better the fuel is.
The apparatus the student used is shown in the diagram.
Thermometer
Calorimeter
100 g of water
Spirit burner
Hydrocarbon fuel
She burned each hydrocarbon fuel for 2 minutes.
Her results are shown in the table.
Name of
hydrocarbon
fuel
Number of
carbon atoms
in a molecule
of hydrocarbon
fuel
Temperature
change of
water in °C
after
2 minutes
Temperature
change per
g of fuel
burned
Observations
Pentane
5
30
60
no smoke
Hexane
6
40
57
very small amount of smoke
Octane
8
55
55
small amount of smoke
Decane
10
57
52
large amount of smoke
Dodecane
12
60
43
very large amount of smoke
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The student investigated only hydrocarbons.
Look carefully at her results.
How well do the student’s results support her hypothesis?
The more carbon atoms there are in a molecule of any fuel, the better the fuel is.
Give reasons for your answer.
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(4 marks)
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1 (e)
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A 0.050 mol sample of a hydrocarbon was burned in excess oxygen.
The products were 3.60 g of water and 6.60 g of carbon dioxide.
1 (e) (i)
Calculate the number of moles of carbon dioxide produced.
Relative atomic masses: C = 12; O = 16.
............................................................................................................................................
............................................................................................................................................
Moles of carbon dioxide = ......................................
(2 marks)
1 (e) (ii) When the hydrocarbon was burned 0.20 mol of water were produced.
How many moles of hydrogen atoms are there in 0.20 mol of water?
............................................................................................................................................
Moles of hydrogen atoms = ...................................
(1 mark)
1 (e) (iii) The amount of hydrocarbon burned was 0.050 mol.
Use this information and your answers to parts (e) (i) and (e) (ii) to calculate the
molecular formula of the hydrocarbon.
If you could not answer parts (e) (i) or (e) (ii) use the values of 0.20 moles carbon
dioxide and 0.50 moles hydrogen. These are not the answers to parts (e) (i)
and (e) (ii).
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Formula = ...............................................................
(2 marks)
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2 (a)
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Lead iodide is an insoluble salt.
Lead iodide can be made by reacting lead nitrate solution with potassium iodide
solution.
Pb(NO3)2(aq) + 2 KI(aq)
PbI2(s) + 2 KNO3(aq)
A student investigated how much lead iodide was made when different volumes of lead
nitrate and potassium iodide solutions were reacted together.
This is the method the student used:





The diagram shows one of the boiling tubes after standing for 15 minutes.
Depth
2 (a) (i)
put 10 cm3 of lead nitrate solution into a boiling tube
add 2 cm3 of potassium iodide solution
leave the boiling tube to stand for 15 minutes
measure the depth of the precipitate formed
repeat using different volumes of potassium iodide solution.
Lead iodide
precipitate
Measure the depth, in mm, of the lead iodide precipitate in the diagram.
Depth = ............................ mm
(1 mark)
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2 (a) (ii) The graph shows the student’s results.
40
35
30
25
Depth of
precipitate 20
in mm
15
10
5
0
0
2
4
6
8
10
12
14
Volume of potassium iodide solution in cm3
There are two anomalous points on the graph.
The anomalous points have been circled.
The table gives some possible causes of anomalous results in this experiment.
For each possible cause, state what effect the cause would have on the depth of
precipitate. Choose your effect from those in the box.
You may use each effect once, more than once or not at all.
greater depth
Possible cause
Some water was in the boiling tube
before the solutions were added
A wider boiling tube was used
less depth
same depth
Effect on precipitate
........................................................................................
........................................................................................
A shorter boiling tube of the same width
was used
........................................................................................
The boiling tube was allowed to stand
for 2 minutes instead of 15 minutes
........................................................................................
(4 marks)
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2 (a) (iii) Describe the relationship shown on the graph between the volume of potassium iodide
solution and the depth of the precipitate.
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(3 marks)
2 (b)
Describe how the student could obtain a dry sample of pure lead iodide from the
mixture in one of the boiling tubes.
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(3 marks)
2 (c)
State one use of a precipitation reaction.
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(1 mark)
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10
3
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Most water contains dissolved compounds.
The concentrations of these dissolved compounds are higher in sea water than in
drinking water.
3 (a) (i)
Draw a ring around the correct answer to complete the sentence.
distillation.
Pure water can be obtained from sea water by
filtration.
neutralisation.
(1 mark)
3 (a) (ii) What is the boiling point of pure water?
3 (b)
................................... °C
(1 mark)
A student wanted to find out how much solid was dissolved in sea water.
This is the method the student used:




3 (b) (i)
measure the mass of an empty evaporating basin
measure 25 cm3 of sea water and pour it into the evaporating basin
heat the evaporating basin gently until all of the water has evaporated
measure the mass of the evaporating basin containing the solid residue.
What piece of apparatus would be suitable for measuring 25 cm3 of sea water?
............................................................................................................................................
(1 mark)
3 (b) (ii) How could the student check that all of the water had evaporated?
............................................................................................................................................
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(2 marks)
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3 (b) (iii) The results the student obtained using 25 cm3 of sea water are:
mass of empty evaporating basin = 23.21 g
mass of evaporating basin and dry solid residue = 24.04 g
Calculate the mass of solid dissolved in 1000 cm3 of the sea water.
............................................................................................................................................
............................................................................................................................................
............................................................................................................................................
Mass dissolved in 1000 cm3 = ............................ g
(2 marks)
3 (c)
In many countries chlorine is added to drinking water supplies.
Why is chlorine added to drinking water?
............................................................................................................................................
............................................................................................................................................
(1 mark)
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3 (d)
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In this question you will be assessed on using good English, organising information
clearly and using specialist terms where appropriate.
Compounds containing fluoride ions are added to some drinking water supplies.
Many scientists have done research into the effects of fluoride ions in drinking water.
Graphs 1, 2 and 3 show some of the results obtained.
Graph 1
20
Key
Water with
fluoride ions
Water without
fluoride ions
15
Percentage
of teeth
showing 10
decay
5
0
25 – 34
35 – 44
45 – 54
55 – 64
Age group in years
65+
Graph 2
90
80
70
Percentage
of children
with decayed 60
teeth
50
40
30
(12)
0
5
10
15
20
25
Concentration of fluoride ions in mg per 1000 g of water
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Graph 3
100
90
Percentage
of children 80
with marked
or brittle teeth 70
60
50
Less than 1.5 – 5.0 5.1 – 12.0 More than
1.5
12.0
Concentration of fluoride ions in mg per 1000 g of water
Evaluate the advantages and disadvantages of adding fluoride ions to drinking water.
You should support your answer with evidence from all three graphs.
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(6 marks)
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14
14
4
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A student investigated the reaction between magnesium metal and dilute hydrochloric
acid.
The student placed 25 cm3 of dilute hydrochloric acid in a conical flask and set up the
apparatus as shown in the diagram.
Gas syringe
Bung
25 cm3 of dilute hydrochloric acid
The student:




took the bung out of the flask and added a single piece of magnesium ribbon
8 cm long
put the bung back in the flask and started a stopwatch
recorded the volume of gas collected after 1 minute
repeated the experiment using different temperatures of acid.
The student plotted his results on a graph.
80
70
60
50
Volume
of gas
collected 40
after 1 minute
in cm3
30
20
10
0
(14)
0
10
20
30
40
50
Temperature of acid in °C
60
70
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4 (a)
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Write the correct state symbols in the equation.
Choose from (s) for solid, (l) for liquid, (g) for gas and (aq) for aqueous.
Mg (….)
4 (b)
+
2 HCl (….)
MgCl2 (….)
+
H2 (….)
(2 marks)
The diagram shows a gas syringe after 1 minute.
0 10 20 30 40 50 60 70 80 90 100 cm3
4 (b) (i)
What volume of gas has been collected in the gas syringe after 1 minute?
Volume = ....................... cm3
(1 mark)
4 (b) (ii) Use the graph to determine the temperature of the acid used in this experiment.
Temperature = ....................... °C
(1 mark)
4 (b) (iii) Calculate the average rate of reaction, in cm3 of hydrogen made per second (cm3/s),
for this experiment.
............................................................................................................................................
............................................................................................................................................
Rate of reaction = ....................... cm3/s
(2 marks)
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4 (c)
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The student’s graph has been reprinted to help you answer this question.
80
70
60
50
Volume
of gas
collected 40
after 1 minute
in cm3
30
20
10
0
0
10
20
30
40
50
Temperature of acid in °C
60
70
One of the results on the graph is anomalous.
4 (c) (i)
Draw a circle on the graph around the anomalous point.
(1 mark)
4 (c) (ii) Suggest what may have happened to cause this anomalous result.
Explain your answer.
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(2 marks)
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4 (d)
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Explain how the student could improve the accuracy of the volume of gas recorded at
each temperature.
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(3 marks)
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4 (e)
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The student then used the same apparatus to measure the volume of gas produced
every 10 seconds at 40 °C.
The student’s results are shown on the graph.
80
70
60
50
Volume
of gas
collected 40
in cm3
30
20
10
0
0
10
20 30 40 50
Time in seconds
60
70
The rate at which the gas was produced got faster over the first 60 seconds.
The student’s teacher gave two possible explanations of why the reaction got faster.
Explanation 1
There was a layer of magnesium oxide on the surface of the magnesium.
The layer of magnesium oxide prevented the magnesium reacting with the acid.
As the magnesium oxide reacted slowly with the acid, the magnesium was exposed to
the acid and hydrogen gas was produced.
Explanation 2
The reaction is exothermic, and so the temperature of the acid increased during the
reaction.
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4 (e) (i)
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Describe further experimental work the student could do to see if Explanation 1 is
correct.
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(2 marks)
4 (e) (ii) Describe further experimental work the student could do to see if Explanation 2 is
correct.
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(2 marks)
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5
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When ammonium chloride is dissolved in water, there is a temperature change.
A student investigated how the temperature of water changed when different masses of
ammonium chloride were added to the same volume of water.
The water used was at room temperature.
The student’s results are shown in the table.
5 (a) (i)
Mass of ammonium
chloride in g
Final temperature
of solution in °C
10
14.5
20
8.5
25
5.5
30
2.5
35
1.0
40
1.0
45
1.0
Use the correct word from the box to complete the sentence.
endothermic
exothermic
reduction
When ammonium chloride dissolves in water, the change can be described
as ...................................................... .
(1 mark)
5 (a) (ii) Give a reason for your answer to part (a) (i). Refer to the table of results in your
answer.
............................................................................................................................................
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(1 mark)
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5 (b)
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The student added the ammonium chloride to water and stirred the mixture.
The water was in a glass beaker.
His teacher said that using a glass beaker could cause inaccurate results.
What could the student have used instead of a glass beaker to improve the accuracy?
Give a reason why this would improve the accuracy of his results.
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(2 marks)
5 (c)
The student made sure his investigation was a fair test.
State two control variables the student should keep the same.
Give a reason why changing each of these two control variables would affect the
temperature change.
Control variable 1 ..............................................................................................................
Reason ..............................................................................................................................
............................................................................................................................................
............................................................................................................................................
Control variable 2 ..............................................................................................................
Reason ..............................................................................................................................
............................................................................................................................................
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(4 marks)
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5 (d) (i)
Do not write
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The student’s results table has been repeated below.
Mass of ammonium
chloride in g
Final temperature
of solution in °C
10
14.5
20
8.5
25
5.5
30
2.5
35
1.0
40
1.0
45
1.0
Plot the results on the grid.
30
25
20
Final
temperature
of solution 15
in °C
10
5
0
0
10
20
30
40
Mass of ammonium chloride in g
50
(2 marks)
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5 (d) (ii) Complete the graph by drawing two straight lines of best fit through the points.
(2 marks)
5 (d) (iii) Use the graph to estimate the temperature of the room.
Show your working on the graph.
Temperature of room = .................................... °C
(2 marks)
5 (e)
Explain why the final temperature was the same for all masses of 35 g and greater.
............................................................................................................................................
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(2 marks)
5 (f)
A second student also did one of the experiments.
This student recorded a final temperature of 14.5 °C.
Both students dissolved 20 g of ammonium chloride in water.
Use the graph to explain the difference in the two final temperatures.
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(2 marks)
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6 (a)
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A student had a colourless solution.
The student thought the solution was dilute hydrochloric acid.
6 (a) (i)
The student added universal indicator to this solution.
What colour would the universal indicator change to if the solution is hydrochloric acid?
............................................................................................................................................
(1 mark)
6 (a) (ii) Describe how the student could show that there are chloride ions in this solution.
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(2 marks)
6 (b)
The results of a titration can be used to find the concentration of an acid.
Burette
Conical flask
25 cm3 dilute hydrochloric acid
and a few drops of
phenolphthalein indicator
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25
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Describe how to use the apparatus to do a titration using 25 cm3 of dilute hydrochloric
acid.
In your answer you should include:


how you will determine the end point of the titration
how you will make sure the result obtained is accurate.
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(4 marks)
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6 (c)
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Hydrochloric acid is a strong acid.
Ethanoic acid is a weak acid.
What is meant by the term weak acid?
............................................................................................................................................
............................................................................................................................................
(1 mark)
6 (d)
The displayed formula of ethanoic acid is:
H
H
C
H
6 (d) (i)
O
C
O
H
On the formula, draw a circle around the functional group in ethanoic acid.
(1 mark)
6 (d) (ii) Ethanoic acid and ethanol react together to make the ester ethyl ethanoate.
Draw the displayed formula of ethyl ethanoate.
(2 marks)
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END OF QUESTIONS
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