12.1 EXTRA QUESTIONS
1.
(a)
same molecular formula / same number of each type of atom (1)
different arrangements of atoms (in the molecule) (1)
(not just same structural formula)
H
H
H
H
C
C
C
C
H
H
H
(1)
H
2
H
H
H
C
C
C
H
CH 3
(1)
H
(b)
H
(c)
(i)
H
H
H
2
M1 % by mass of H = 7.7(0)% (1)
M2
mol H = 7.70 / 1 = 7.70
mol C = 92.3 / 12 = 7.69 (1)
M3 (ratio 1:1 ) CH
Credit variations for M2 78 ×
77
78 92.3
= 6 and
=6

12 100
100
Correct answer = 3 marks
(ii)
(CH has empirical mass of 13 and
78
= 6 ) C6H6
13
Correct answer 1 mark
4
(iii)
methylpropene / 2–methylpropene not 2-methylprop-2-ene (1)
ignore wrong punctuation
CH3 H
H
C
C
C
CH3
H
C
H
or
H
H
C
CH3
H
allow 1 mark for but-2-ene with its correct structure (1)
2
minimum structure is CH 2 = CCH 3 or CH 2 = C(CH 3 )CH 3
CH 3
[10]
2.
(a)
(i)
but-1-ene (1)
(ii)
two H on one carbon of double bond (1)
(iii)
CH3CH=CHCH3 (1)
(iv)
(1)
CH 3
C
4
CH 2
CH 3
[4]
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1
3.
(a)
H3C
CH 3
C
C
H
H
H3C
H
C
(1)
C
H
CH 3
(1)
H
accept
CH 3
C
C
H
H
CH 3
and
CH 3
C
C
CH 3
H
Credit 1 mark for a correct formula for but-2-ene
Credit 1 mark for any pair of cis / trans isomers
Geometric(al)
Or cis-trans
Or diastereoisomerism
NOT stereoisomerism
3
(b)
two H on carbon in double bond (1)
[4]
4.
(a)
(i)
H
H
Br
H
H
C
C
C
H
C
H
H
H
H
(1)
CH3CH2CH(Br)CH3 (1)
If ‘B’ used in place of ‘Br’ allow M2
(ii)
2–bromo (–2) methylpropane (1)
allow (2–) methyl (–2–) bromopropane
3
[3]
TOTAL 2 marks
5.
(a)
Give the structural formula, showing all covalent bonds for the CFC 1, 1, 2,
trichloro-1, 2, 2-trifluoroethane.
Cl
Cl
F
C
C
F
Cl
F
(1)
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2
(b)
1, 1, 1, 2-tetrafluoroethane can be made by a two stage synthesis. Write the equations for the
following reactions.
(i)
1,1,2,2-tetrachloroethane is reacted with chlorine and hydrogen fluoride to produce
1, 1-dichlorotetrafluoroethane and hydrogen chloride.
Cl
Cl
H
C
C
H
Cl
Cl
(ii)
+ 2 Cl
Cl
Cl
F
C
C
F
F
Cl
F
+
+
4H
F
6 H
Cl
The 1,1-dichlorotetrafluoroethane is reduced by hydrogen gas to 1, 1, 1,2tetrafluoroethane and hydrogen chloride.
Cl
Cl
F
C
C
F
F
F
+
2 H
H
H
H
F
C
C
F
F
F
+
2 H
Cl
(2)
TOTAL 3 marks
6.
(a)
Define the term structural isomerism.
same molecular formula / same number of each type of atom (1)
different arrangements of atoms (in the molecule) (1)
(not just same structural formula)
(2)
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3
(b) Draw the graphical formulae for the two structural isomers of C4H10
Isomer 1
H
Isomer 2
H
H
H
H
C
C
C
C
H
H
H
H
H
H
H
H
H
C
C
C
H
CH 3
H
H
(1)
(1)
(2)
(c)
A hydrocarbon W contains 92.3% carbon by mass. The relative molecular mass of W is 78.0
(i)
Calculate the empirical formula of W.
M1 % by mass of H = 7.7(0)% (1)
M2
mol H = 7.70 / 1 = 7.70
mol C = 92.3 / 12 = 7.69 (1)
M3 (ratio 1:1 ) CH
Credit variations for M2 78 ×
77
78 92.3
= 6 and
=6

12 100
100
Correct answer = 3 marks
(ii)
Calculate the molecular formula of W.
(CH has empirical mass of 13 and
78
= 6 ) C6H6
13
Correct answer 1 mark
(4)
TOTAL 8 marks
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