A Level Chemistry B (Salters) H433/02 Scientific literacy in chemistry - Question Paper Tuesday 12 October 2021 Preview
Answer all the questions.
1 Gas-liquid chromatography can be used to analyse the components of car petrol.
sample
injector
waste
detector
flow controller
carrier gas column oven
A gas chromatograph
column
(a) (i) State an important property of the carrier gas.
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(ii) What does the column consist of?
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(b) The first four components of a sample of petrol to emerge from the column are shown in
Table 1.1 in the order they come out.
1 methylbenzene
2 2-methylheptane
3 3-methylheptane
4 octane
Table 1.1
(i) Suggest the method used to identify these compounds as they emerge from the column.
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(ii) Which of the compounds in Table 1.1 has the shortest retention time?
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(c) Suggest, with reasons, which of compounds 2, 3 and 4 from Table 1.1 has the highest boiling
point.
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(d) Octane can be cracked.
Write an equation for the cracking of octane into but-2-ene, CH3CH=CHCH3, and one other
compound.
Use molecular formulae.
[1]
(e) Explain why but-2-ene has two stereoisomers.
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(f) Some reactions of but-2-ene are shown in the diagram below.
Complete the diagram by filling in the incomplete boxes.
CH3CHBrCHBrCH3
Br2
CH3COCH2CH3
but-2-ene
CH3CH=CHCH3
Observation when reaction with Br2 occurs:
Reagents and conditions
used in a laboratory:
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Structural formula of
one repeat unit of the polymer:
polymerisation
concentrated
H2SO4 followed
by water
Full structural formula of product:
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[5]
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(g) A hydrocarbon is completely burned.
11 g of carbon dioxide and 6.0 g of water are formed.
Calculate the empirical formula of the hydrocarbon.
formula ........................................................... [3]
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2 Some students are investigating the rusting of iron.
They use the electrode potentials in Table 2.1.
Half equation E o / V
1 Zn2+(aq) + 2e– Zn(s) – 0.76
2 Fe2+(aq) + 2e– Fe(s) – 0.44
3 .......O2(g) + H2O(l) + ........e– 2OH–(aq) + 0.40
Table 2.1
(a) (i) Complete half-equation 3 in Table 2.1 by writing numbers on the dotted lines. [2]
(ii) Use oxidation states to state and explain what is being reduced in half-equation 3 in
Table 2.1.
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(b) The students set up a cell under standard conditions using half-equations 1 and 2 in Table 2.1.
They aim to measure Eo
cell.
(i) Complete the diagram of their apparatus.
Indicate how standard conditions are obtained
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