DP Chemistry (last assessment 2024)

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Question 22M.2.hl.TZ1.b(iii)

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Date May 2022 Marks available [Maximum mark: 1] Reference code 22M.2.hl.TZ1.b(iii)
Level hl Paper 2 Time zone TZ1
Command term State Question number b(iii) Adapted from N/A
b(iii).
[Maximum mark: 1]
22M.2.hl.TZ1.b(iii)

Magnesium is a reactive metal often found in alloys.

Magnesium is sometimes used as a sacrificial anode to protect steel from corrosion.

This cell causes the electrolytic reduction of water on the steel. State the half-equation for this reduction.

[1]

Markscheme

2 H2O + 2 e- → H2 + 2 OH- ✔


Accept equation with equilibrium arrows.

Examiners report

Mediocre performance; some candidates had difficulty writing the reduction half-equation for water, the typical error included O2(g) gas in the reactant or product, rather than H2(g) in the product or including an equation with Fe(s) and H2O(l) as reactants.

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