DP Chemistry (last assessment 2024)

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Question 19N.3.hl.TZ0.20a

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Date November 2019 Marks available [Maximum mark: 2] Reference code 19N.3.hl.TZ0.20a
Level hl Paper 3 Time zone TZ0
Command term Deduce, Formulate Question number a Adapted from N/A
a.
[Maximum mark: 2]
19N.3.hl.TZ0.20a

A proton-exchange membrane (PEM) fuel cell uses pure hydrogen gas as the fuel and a proton exchange membrane as the electrolyte.

 

(a)

Deduce the half-equations for the reactions occurring at the electrodes.


Anode (negative electrode):

Cathode (positive electrode):

[2]

Markscheme

Anode (negative electrode):
H2 (g) → 2H+ (aq) + 2e− ✔

Cathode (positive electrode):
O2 (g) + 4H+ (aq) + 4e− → 2H2O (l) ✔

NOTE: Accept any correct integer or fractional coefficients. Award [1 max] for M1 and M2 if correct half-equations are given at the wrong electrodes OR if incorrect reversed half-equations are given at the correct electrodes.

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