DP Chemistry (last assessment 2024)

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Question 19M.3.hl.TZ1.17b(i)

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.hl.TZ1.17b(i)
Level hl Paper 3 Time zone TZ1
Command term Deduce Question number b(i) Adapted from N/A
b(i).
[Maximum mark: 2]
19M.3.hl.TZ1.17b(i)

E10 is composed of 10% ethanol and 90% normal unleaded fuel.

(b(i))

Ethanol can be used in a direct-ethanol fuel cell (DEFC) as illustrated by the flow chart.

Deduce the half-equations occurring at electrodes A and B.

Electrode A: 

Electrode B:

[2]

Markscheme

Electrode A: C2H6O (aq) + 3H2O (l) → 12H+ (aq) + 12e– + 2CO2 (g)   [✔]

Electrode B: 3O2 (g) + 12H+ (aq) + 12e– → 6H2O (l)    [✔]

 

Note: Accept balanced equations with integer or fractional coefficients.

Penalize equilibrium arrows once only.

Examiners report

Some candidates did very well and deduced the half-equations occurring in a DEFC as illustrated in a flow chart. A few used equilibrium arrows and lost a mark. Some candidates failed to balance the half-equations.

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