DP Chemistry (last assessment 2024)

Question 20N.3.sl.TZ0.4b(ii)

Date	November 2020	Marks available	[Maximum mark: 2]	Reference code	20N.3.sl.TZ0.4b(ii)
Level	sl	Paper	3	Time zone	TZ0
Command term	Write	Question number	b(ii)	Adapted from	N/A

b(ii).

[Maximum mark: 2]

20N.3.sl.TZ0.4b(ii)

There has been significant growth in the use of carbon nanotubes, CNT.

(b(ii))

Pure magnesium needed for making alloys can be obtained by electrolysis of molten magnesium chloride.

Write the half-equations for the reactions occurring in this electrolysis.

[2]

Markscheme

Anode: $2 {Cl}^{-} \to {Cl}_{2} (g) + 2 e^{-}$ ✔

Cathode: ${Mg}^{2 +} + 2 e^{-} \to Mg (l)$ ✔

Accept $C l^{-} \to C l_{2} (g) + e^{-}$ .

Award [1 max] for correct equations at incorrect electrodes.

Examiners report

This was a very popular option with approximately 34% of candidates attempting Option B. Many students appeared well prepared for this option. Some candidates continue to provide answers with a heavy Biology bias that often make them lose valuable points.

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Core

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Options » A: Materials » A.2 Metals and inductively coupled plasma (ICP) spectroscopy

Options » A: Materials

Core » Topic 9: Redox processes » 9.2 Electrochemical cells

Core » Topic 9: Redox processes

Question 20N.3.sl.TZ0.4b(ii)

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