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.
Predict the chemical shifts and integration for each signal in the 1H NMR spectrum for ethanol using section 27 of the data booklet.
Markscheme
C2H5OH(g) + O2(g) → CH3COOH(aq) + H2O(l)
Accept any correct formula for reactants and products.
[1 mark]
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]