EdExcel a Level Chemistry Unit 9 Mark Scheme Jan 2000

8/16/2019 EdExcel a Level Chemistry Unit 9 Mark Scheme Jan 2000

1/3

Winter 2000 CH4 Mark Scheme

1

1. (a) C 69.8 / 12 = 5.8 / 1.16 5

H 11.6 / 1 = 11.6 1 / 1.16 10

O 18.6 / 16 = 1.16 / 1.16 1

EF is C5H10O(1) 2

(b) (i) amount NaOH = 0.0374dm3 × 0.211moldm–3 (1)

= 7.89 × 10–3 mol

amount of W = 7.89 × 10–3 mol(1)

Mr = 1.36 g = 172 (gmol–1)(1)

7.89×10–3 molNote: can get 3 marks for correct calculation which

‘assumes’ second mark. 3

(ii) Emp formula mass = 86 thus MF is Cl0H20O2(1)

(some reasoning needed for this mark) 1

(iii) C9H19COOC2H5 + NaOH ➤ C9H19COONa + C2H5OH (2)

correct ester formula (1) balanced equation (1) or ionic equation

Note: max (1) if added up formulae used or wrong ester formula

or RCOOC2H5 2

[8]

2. (a) Correct arrows involving C=C and H–Br(1) Correct intermediate with positive charge(1)

Correct arrow from Br– towards carbon atom (1)

C CCH CH CH CHBrCHH H

H HH H

H

C C3 3 3 3

:Br–

H Br 3

Note: if product is 1-bromo product max 2 for full correct mechanism.

(b) (i) Reagent : magnesium(1)

dry ethoxyethane / ether(1)

iodine catalyst / warm under reflux (or at room temperature)(1) 3

(ii) Reagent : aqueous or dilute sodium hydroxide(1)

Conditions: boil / heat under reflux(1) 2

(c) Reagent : carbon dioxide (solid)(1)

Reagent second stage: water or dilute named acid (1)

Note: a route using methanal followed by oxidation can score (2) marks 2

(d)

CCH

CH

CHCH

H

O

C C HO3

3

33 (2)

2

Note: if one branched and one straight chain on correct ester linkage (1) [12]

et


2/3


2

3. (a) NN C

HH O

C

O

n

Correct structure if linkage (1)

Some evidence of continuation of molecule (1) 2

(b) Peak at A : C=O (1)

Peak at B : C– O (1)

Spectrum is that of benzene – 1,4- dicarboxylic acid (1) 3

(c) (i) To prevent the volatile reactant / dimethyl benzene boiling off (1)

(ii) Because the diacid is soluble in hot water (1)

(iii) M.Pt not sharpor different from / not consistent with / less than data book (1) 3

(d) (i)

C C

F FH HF FH H

F FH HF FH H

C CC CC C

n n

or

(or H...F...F...H on chain)

Correct repeating structure (1)

Some evidence of continuation of molecule (1) 2

(ii) Kevlar : condensation(1)

PDFE : addition (1) 2

(e) (i) more carbon dioxide per kJ of energy (1)

therefore more global warming/ more greenhouse gas produced (1) 2

(ii) Some reference to need for special arrangements for filling tank /dangerous in the event of a crash /more weight as gas tank

weighs more than petrol tank / more likely to leak because gas

under pressure (1) 1[15]

4. (a) (i)

CH CHCl CH OH

CH CH(OH) COO Na

CH CHCl COOH

COOH

COOH

3

3

32

+–

A

C

B

D

4 × 1 = 4

B consequential on A

C consequential on B

(ii) 2-chloropropan-1-ol (mark consequentially) 1

et


3/3


3

(b)C H COCl C H CONH C H CN C H CH NH5 5 5 522 2 2 2 2 2

NH P O Na/C H OH3 5 5

4

2 2

or LiAlH

(1) (1) (1) (1) (1)

or

C H COCl C H COOH C H CH OH C H CH Br

C H CH NH

5 5 5 5

5

2 2

2 2

3

2 2 2 2

2

H O LiAlH KBr/concH SO2 4 42

(1)

(1)

(1) (1)

(1)NH

5

(c) (i)

NH + NaNO + 2HCl N NCl + 2H O + NaCl22 2+ –

1 for diazo cation + (1) for rest of equation 2

(ii) if greater than 5♦ C X decomposes (1)

if less than 0 ♦ C rate (of formation of X) is too slow (1) 2

(iii) N N

OH (1)(1)

for N=N link for link to correct ring

next to –OH 2

[16]

et

Documents

EdExcel a Level Chemistry Unit 9 Mark Scheme Jan 2000