june 1999 paper 4
TRANSCRIPT
TIME 1 hour
INSTRUCTIONS TO CANDIDATES
Write your name, Centre number and candidate number in the spaces at the top of this page.
Answer all questions.
Write your answers in the spaces provided on the question paper.
INFORMATION FOR CANDIDATES
The number of marks is given in brackets [ ] at the end of each question or part question.
You should use names, not symbols, when describing all reacting chemicals and the products formed.
Mathematical tables are available.
You may use a calculator.
UNIVERSITY OF CAMBRIDGE LOCAL EXAMINATIONS SYNDICATE
General Certificate of Education Ordinary Level
CHEMISTRY 5070/4PAPER 4 Alternative to Practical
Thursday 24 JUNE 1999 Morning 1 hour
Candidates answer on the question paper.Additional materials:
Mathematical tablesRuler (cm/mm)
This question paper consists of 15 printed pages and 1 blank page.
SB (CW) QF92366/3© UCLES 1999 [Turn over
CandidateCentre Number Number
Candidate Name
FOR EXAMINER’S USE
2
5070/4 S99
1 What is the volume of liquid, to the nearest cm3, in the measuring cylinder?
...................................... cm3 [1]
2 A student was given some 0.100 mol/dm3 hydrochloric acid and did some tests with it toinvestigate its properties.
(a) A few drops of litmus solution were added to 5 cm3 of hydrochloric acid.
An excess of aqueous sodium hydroxide was added.
What colour change was seen?
The colour changed from .......................... to .......................... [1]
(b) A small piece of magnesium was added to 5 cm3 of hydrochloric acid. A gas wasproduced.
Name the gas.
..........................................................................................................................................
Give a test for the gas.
..........................................................................................................................................
......................................................................................................................................[2]
30
40
50
20
10
cm 3
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(c) A few grams of powdered calcium carbonate were added to 5 cm3 of hydrochloric acid.
(i) What did the student observe?
..................................................................................................................................
(ii) Name the gas evolved.
..................................................................................................................................
(iii) Give a test for this gas.
..................................................................................................................................
..................................................................................................................................[3]
3 A student used zinc to prepare zinc nitrate.The zinc nitrate was then heated to produce zinc oxide.
Some zinc was put in a weighed evaporating dish.The dish was reweighed.
Mass of dish + zinc = 22.20 gMass of dish = 15.70 g
(a) Calculate the mass of zinc.
The mass of zinc = ................ g. [1]
An acid was slowly added until all the zinc had dissolved.Zinc nitrate solution was produced.
(b) Name the acid.
......................................................................................................................................[1]
The solution was evaporated to dryness and the resultant solid was heated in a fumecupboard. The following reaction took place.
2Zn(NO3)2 → 2ZnO + 4NO2 + O2
(c) Why was the heating done in a fume cupboard?
..........................................................................................................................................
......................................................................................................................................[1]
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After cooling, the dish was weighed. It was then heated again, cooled and reweighed.
(d) Why was the dish heated again?
......................................................................................................................................[1]
Final mass of dish + zinc oxide = 23.40 g
(e) Calculate the mass of zinc oxide.
.......................................................................................................................... g [1]
(f) Using your answers to (a) and (e), calculate the percentage yield of zinc oxide from theinitial mass of zinc.Ar : Zn, 65; O, 16.
......................................................................................................................................[2]
In Questions 4–7 inclusive place a tick (✔) in the box against the best answer.
4 A gas, when passed through aqueous potassium dichromate(VI), changed the colour of thesolution from orange to green.
Which gas was used?
(a) chlorine
(b) ethane
(c) oxygen
(d) sulphur dioxide[1]
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5 A student was given a sample of damp soil which was known to be acidic. Which of thefollowing substances cannot be used to neutralise the soil?
(a) ammonia
(b) lime
(c) salt
(d) slaked lime[1]
6 Several strips of a metal X were placed in test-tubes containing aqueous solutions as shownin the diagrams.
A deposit was seen on X in two tubes only.
What was metal X?
(a) iron
(b) magnesium
(c) potassium
(d) silver[1]
metal X
CaCl 2(aq)
metal X
CuCl 2(aq)
metal X
NaCl (aq)
metal X
ZnCl 2(aq)
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7 Four experiments were set up to find out how nails could be prevented from rusting.
In which tube did the nails rust?
(a)
(b)
(c)
(d)[1]
oxygen
paintednails in
tap water
(a)
air
unpaintednails in a
solid dryingagent
(b)
air
unpaintednails indistilledwater
(c)
oxygen
layer of oil
unpaintednails inboiled
tap water(d)
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8 P is a mixture of iron(II) sulphate and iron(III) sulphate.
A student determined the percentage of iron(II) sulphate in the mixture by using0.0200 mol/dm3 potassium manganate(VII), solution R.
A sample of P was added to a previously weighed container, which was then reweighed.
Mass of container + P = 19.16 gMass of container = 12.98 g
(a) Calculate the mass of P used in the experiment.
...........................................................................................................................g [1]
The sample of P was placed in a flask, dissolved in 100 cm3 of dilute sulphuric acid and thesolution was made up to 250 cm3 with distilled water. This was solution S.
A 25.0 cm3 sample of S was measured into a conical flask.
(b) What should be used to measure this volume?
......................................................................................................................................[1]
Potassium manganate(VII), which is purple, oxidises iron(II) ions in the mixture.
(c) Suggest why potassium manganate(VII) does not react with iron(III) ions.
..........................................................................................................................................
......................................................................................................................................[1]
Solution R was run from the burette into a flask containing S.
(d) How would the student know when the end-point was reached?
..........................................................................................................................................
......................................................................................................................................[1]
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(e) Three such titrations were done. Parts of the burette before and after each titration areshown below.
Using the diagrams, complete the following table.
Summary:
Tick (✔) the best titration results.
Using these results, the average volume of R required was ......................... cm3 [4]
R is 0.0200 mol/dm3 potassium manganate(VII).
(f) Calculate how many moles of potassium manganate(VII) were present in the averagevolume of R calculated in (e).
................................. moles of KMnO4 [1]
0
1
2
24
25
26
2
3
4
25
26
27
17
18
19
42
43
44
ForExaminer’s
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titration number
final burette reading / cm3
initial burette reading / cm3
volume of R used / cm3
best titration results (✓)
first second third
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(g) One mole of KMnO4 reacts with five moles of iron(II) sulphate, FeSO4.
Calculate how many moles of FeSO4 were present in 25.0 cm3 of S.
................................. moles of FeSO4 [1]
(h) Calculate how many moles of FeSO4 were present in 250 cm3 of S.
................................. moles of FeSO4 [1]
(i) Using your answer to (h), calculate the mass of FeSO4 present in the solution of S.(Mr: FeSO4, 152)
................................. g of FeSO4 [1]
(j) Using your answers to (a) and (i), calculate the percentage of FeSO4 in the sample of P.
................................. % of FeSO4 [1]
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9 The following table shows the tests a student did on substance G and the conclusions madefrom the observations.
Complete the table by describing these observations and describe the test and observationswhich led to the conclusion from test 4.
1
2
3
4
Conclusion: The formula for substance G is ........................................................... [9]
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test
G was dissolved in water andthe solution divided into threeparts for tests 2, 3 and 4.
(a) To the first part, aqueoussodium hydroxide wasadded until a changewas seen.
(b) An excess of aqueoussodium hydroxide wasadded to the mixturefrom (a).
(a) To the second part,aqueous ammonia wasadded until a changewas seen.
(b) An excess of aqueousammonia was added tothe mixture from (a).
observations conclusions
G is not a compoundof a transition metal.
G may contain Zn2+
ions.
The presence of Zn2+
ions is confirmed.
G contains I– ions.
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10 A student plated a metal ring with silver using the apparatus shown below.
The ring was weighed and placed in the solution. This was the cathode. The circuit wascompleted and a current of 1 A was allowed to flow.
(a) What was the purpose of the variable resistor?
......................................................................................................................................[1]
A
aqueoussilver nitrate
metal ring
variableresistor
carbon(graphite)anode
+ –
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The ring was removed every ten minutes, carefully washed, dried and weighed. This wasexperiment I.
The experiment was repeated using a current of 1.5 A. This was experiment II.
The results from both experiments are shown in the table.
(b) Complete the table by calculating the total increase in mass after each ten minutes inboth experiments.
[2]
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time/minmass
ofring/g
current 1 A current 1.5 A
experiment I experiment II
totalincrease in
mass/g
totalincrease in
mass/g
massof
ring/g
0 8.80 0.00 8.80 0.00
10 9.10 0.30 9.25 0.45
20 9.40 0.60 9.70
30 9.70 10.15
40 10.00 10.60
50 10.30 10.60
60 10.60 10.60
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(c) Plot the two sets of results on the grid below. Join each set of results using straightlines. Label the lines I and II corresponding to the two experiments.
[4]
00 10 20 30 40 50 60
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
time/min
totalincreasein mass
/g
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(d) What was the time taken to deposit 1.00 g of silver in each experiment?
I ................................................... g
II ................................................... g [2]
(e) Calculate how much more silver was deposited after 15 minutes in experiment II than inexperiment I.
mass of silver deposited in 15 minutes
in II ................................................... g
mass of silver deposited in 15 minutes
in I ................................................... g
difference in mass = .......................... g [2]
(f) Predict the mass of silver deposited in experiment I if the experiment had continued for70 minutes. Explain your answer.
....................................................................................................................................... g
Explanation ......................................................................................................................
......................................................................................................................................[2]
(g) Suggest how the rate of deposition of a metal during electrolysis is influenced by thevalue of the current.
......................................................................................................................................[1]
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11 A student did the following experiments with copper powder.
(a) He heated the copper powder in air and a black solid was formed.
Name the compound formed.
......................................................................................................................................[1]
(b) A small volume of dilute sulphuric acid was added to the substance formed in (a). Thesolid reacted with the acid to form a solution.
(i) What was the colour of the solution?
..................................................................................................................................
(ii) Name the solution.
..................................................................................................................................[2]
(c) Some powdered zinc was added to the solution formed in (b) and left for a while.
Describe what was seen.
..........................................................................................................................................
..........................................................................................................................................
......................................................................................................................................[3]
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