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6242/01
Examiner’s use only
Edexcel GCE
Team Leader’s use only
Chemistry
Advanced Subsidiary
Unit Test 2
Wednesday 6 June 2007 – Morning
Time: 1 hour
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Number Blank
1
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3
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5
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Nil
Items included with question papers
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6
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Instructions to Candidates
In the boxes above, write your centre number, candidate number, your surname, initial(s) and
signature.
Answer ALL the questions. Write your answers in the spaces provided in this question paper.
Show all the steps in any calculations and state the units.
Information for Candidates
The total mark for this paper is 60. The marks for individual questions and parts of questions are
shown in round brackets: e.g. (2). There are 12 pages in this question paper.
A Periodic Table is printed on the back cover of this question paper. All blank pages are indicated.
Advice to Candidates
You are reminded of the importance of clear English and careful presentation in your answers.
You will be assessed on your Quality of Written Communication in this paper.
Total
This publication may be reproduced only in accordance with
Edexcel Limited copyright policy.
©2007 Edexcel Limited.
Printer’s Log. No.
N26022A
W850/R6242/57570 7/7/7/3/23,100
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*N26022A0112*
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Answer ALL the questions. Write your answers in the spaces provided.
1.
Chlorine is manufactured by the electrolysis of concentrated brine in a membrane cell.
(a) State the material from which the anode is made.
.......................................................................................................................................
(1)
(b) Write the half-equation for the reaction at the anode.
.......................................................................................................................................
(1)
(c) Explain whether the reaction at the anode is an oxidation or a reduction process.
.......................................................................................................................................
.......................................................................................................................................
(1)
(d) Which ions are able to pass through the membrane in this cell?
.......................................................................................................................................
(1)
(e) Identify the product at the cathode.
.......................................................................................................................................
(1)
(f) Write the overall equation for the decomposition of brine by electrolysis.
.......................................................................................................................................
(2)
(g) State ONE large-scale use of chlorine.
.......................................................................................................................................
(1)
(Total 8 marks)
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*N26022A0212*
Q1
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2.
(a) Chlorofluorocarbons, CFCs, are useful compounds as they are non-flammable and
unreactive. In the stratosphere, the C—Cl bonds are broken producing free radicals.
(i) Draw the structure of 1,1,2-trichloro-1,2,2-trifluoroethane.
(1)
(ii) Suggest why C—F bonds are not broken in the stratosphere, whereas C—Cl
bonds are.
................................................................................................................................
(1)
(iii) What are free radicals and what is needed to produce them from CFCs?
................................................................................................................................
................................................................................................................................
(2)
(b) (i) Draw the repeating units in
poly(chloroethene)
poly(tetrafluoroethene).
(2)
(ii) Give ONE important use of each of these polymers.
poly(chloroethene)
................................................................................................................................
poly(tetrafluoroethene)
................................................................................................................................
(2)
Q2
(Total 8 marks)
*N26022A0312*
3
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3.
(a) Name each of the following organic compounds and the homologous series to which
it belongs.
H H H
H H H H
H—C—C—C—H
H—C—C—C—C—H
H O H
H
H H
H—C—H
H
H—C—H
H
Name ....................................................
Name ....................................................
Homologous Series ..............................
Homologous Series ..............................
(4)
(b) (i) Draw the TWO structural isomers of C2H2Cl2.
(2)
(ii) Identify which of the two structural isomers of C2H2Cl2 can exist as geometric
isomers. Explain why geometric isomerism can occur.
Identity
Explanation
................................................................................................................................
................................................................................................................................
................................................................................................................................
(2)
4
*N26022A0412*
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(c) Classify the following organic reactions.
(i) C2H4 + HBr → C2H5Br
................................................................................................................................
(1)
(ii) C2H5Br + CN– → C2H5CN + Br–
................................................................................................................................
(1)
(d) A hydrocarbon has the empirical formula CH2 and a relative molecular mass of 70.
Write the molecular formula of the hydrocarbon.
.......................................................................................................................................
(1)
Q3
(Total 11 marks)
*N26022A0512*
5
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4.
(a) When excess chlorine and methane are mixed at room temperature and pressure no
reaction takes place but when ultraviolet light is shone into the mixture an explosion
occurs, producing carbon and hydrogen chloride.
CH4(g) + 2Cl2(g)
uv
C(s) + 4HCl(g)
∆H = –219 kJ mol–1
Calculate the mass of methane needed to produce 1000 kJ of energy.
(2)
(b) Draw a labelled reaction profile for the reaction between methane and chlorine
and use it to explain why the reaction does not take place unless ultraviolet light is
present.
Enthalpy
Progress of reaction
Explanation
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
(5)
6
*N26022A0612*
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(c) Hydrogen gas is manufactured by passing methane and steam over a heated catalyst.
CH4(g) + H2O(g) ⇌
CO(g) + 3H2(g)
∆H = +206 kJ mol–1
Explain the effect, if any, on the equilibrium yield of hydrogen by using:
(i) a higher pressure
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
(2)
(ii) a higher temperature
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
(2)
(iii) a catalyst.
................................................................................................................................
(1)
Q4
(Total 12 marks)
*N26022A0712*
7
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5.
(a) Define the term standard enthalpy of combustion.
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
(3)
(b) The following standard enthalpies of combustion are needed to calculate the standard
enthalpy of formation of ethanol, C2H5OH.
Substance
Standard enthalpy of
combustion /kJ mol–1
carbon, C (s, graphite)
–394
hydrogen, H2 (g)
–286
ethanol, C2H5OH (l)
–1371
(i) Complete the Hess’s Law cycle by filling in the box and labelling the arrows with
the enthalpy changes.
∆H f
2C(s) + 3H2(g) + 3½O2(g)
○
C2H5OH(l) + 3O2(g)
...........................
...........................
...........................
...........................
............................... + ...............................
(3)
8
*N26022A0812*
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(ii) Use your Hess’s Law cycle to calculate the standard enthalpy of formation of
ethanol.
(2)
(c) Ethanol, C2H5OH, can be converted into propanenitrile, CH3CH2C≡N in two steps.
Step 1
C2H5OH
Step 2
C2H5I
CH3CH2C≡N
Give the reagents for the steps.
Step 1
Reagents
.......................................................................................................................................
.......................................................................................................................................
Step 2
Reagent
.......................................................................................................................................
(3)
Q5
(Total 11 marks)
*N26022A0912*
9
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6.
The first step in the manufacture of nitric acid is the catalytic oxidation of ammonia. The
reaction is usually carried out at 900 °C.
(a) (i) Balance this equation.
..........NH3 + ..........O2
→
..........NO + ..........H2O
∆H = –900 kJ mol–1
(1)
(ii) Identify the catalyst used in this reaction.
................................................................................................................................
(1)
(iii) State and explain the effect on the rate of reaction of using a temperature lower
than 900 °C.
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
................................................................................................................................
(3)
(b) Outline the steps which convert nitrogen monoxide, NO, from the oxidation of
ammonia, into nitric acid. Identify the intermediate compound.
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
.......................................................................................................................................
(4)
(c) Give ONE important use of nitric acid.
.......................................................................................................................................
(1)
(Total 10 marks)
TOTAL FOR PAPER: 60 MARKS
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