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Date May 2018 Marks available 3 Reference code 18M.3.hl.TZ2.27
Level HL Paper 3 Time zone TZ2
Command term Predict Question number 27 Adapted from N/A

Question

Ethanol can be detected by a variety of instruments.

Fuel cells use an electrochemical process to determine the concentration of ethanol.

Formulate the overall equation for this process.

[1]
a.

Predict the chemical shifts and integration for each signal in the 1H NMR spectrum for ethanol using section 27 of the data booklet.

[3]
b.

Markscheme

C2H5OH(g) + O2(g) → CH3COOH(aq) + H2O(l)

 

Accept any correct formula for reactants and products.

[1 mark]

a.

R–OH:

1.0–6.0 «ppm» AND 1 H

R–O–CH2–:

3.3–3.7 «ppm» AND 2 H

–CH3:

0.9–1.0 «ppm» AND 3 H

 

Award [1] for the ratio of 1:2:3 (in any order).

Award [2] for three correct chemical shifts without integration.

Award [1] for two correct chemical shifts without integration.

For each chemical shift accept a specific value within the range.

Assignment of proton to fragment (eg, R–OH) is not required in each case.

[3 marks]

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Additional higher level (AHL) » Topic 21: Measurement and analysis » 21.1 Spectroscopic identification of organic compounds
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