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Question 18M.2.hl.TZ2.9a.ii

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.2.hl.TZ2.9a.ii
Level hl Paper 2 Time zone TZ2
Command term Explain Question number a.ii Adapted from N/A
a.ii.
[Maximum mark: 2]
18M.2.hl.TZ2.9a.ii

Organic compounds often have isomers.

A straight chain molecule of formula C5H10O contains a carbonyl group. The compound cannot be oxidized by acidified potassium dichromate(VI) solution.

(a.ii)

Mass spectra A and B of the two isomers are given.

M18/4/CHEMI/HP2/ENG/TZ2/09.a.ii_01

Explain which spectrum is produced by each compound using section 28 of the data booklet.

 

[2]

Markscheme

A:

CH3CH2COCH2CH3 AND «peak at» 29 due to

(CH3CH2)+/(C2H5)+/(M – CH3CH2CO)+

OR

CH3CH2COCH2CH3 AND «peak at» 57 due to

(CH3CH2CO)+/(M – CH3CH2)+/(M – C2H5)+

 

B:

CH3COCH2CH2CH3 AND «peak at» 43 due to

(CH3CH2CH2)+/(CH3CO)+/(C2H3O)+/(M – CH3CO)+

 

Penalize missing “+” sign once only.

Accept “CH3COCH2CH2CH3 by elimination since fragment CH3CO is not listed” for M2.

[2 marks]

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