DP Chemistry (last assessment 2024)

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Question 18M.3.hl.TZ1.5e

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.3.hl.TZ1.5e
Level hl Paper 3 Time zone TZ1
Command term Calculate Question number e Adapted from N/A
e.
[Maximum mark: 2]
18M.3.hl.TZ1.5e

Aluminium is produced by the electrolysis of a molten electrolyte containing bauxite.

(e)

The concentration of aluminium in drinking water can be reduced by precipitating aluminium hydroxide. Calculate the maximum concentration of aluminium ions in water of pH 7 at 298 K. Solubility product of aluminium hydroxide = 3.3 × 10−34 at 298 K.

[2]

Markscheme

Ksp = [Al3+][OH–]3 «= 3.3 × 10–34»

[Al3] = « 3.3 × 10 − 34 ( 1 × 10 − 7 ) 3 = » 3.3 × 10–13 «mol dm–3»

 

Award [2] for correct final answer.

[2 marks]

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