DP Chemistry (last assessment 2024)

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Question 19M.3.hl.TZ2.8b

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.hl.TZ2.8b
Level hl Paper 3 Time zone TZ2
Command term Determine Question number b Adapted from N/A
b.
[Maximum mark: 2]
19M.3.hl.TZ2.8b

Heavy metals are toxic even in very low concentrations.

(b)

Determine the maximum concentration of lead(II) ions at 298 K in a solution in which the concentration of carbonate ions is maintained at 1.10 × 10−4 mol dm−3. Use section 32 of the data booklet.

[2]

Markscheme

«Ksp = 7.40 × 10–14»
Ksp = [Pb2+][CO32–]  [✔]

[Pb2+] «= 7.40 × 10 − 14 1.10 × 10 − 4 » = 6.73 × 10–10 «mol dm–3»  [✔]

 

Note: Award [2] for correct final answer.

Examiners report

Majority of the candidates managed to get two marks in determining the maximum concentration of lead(II) ions using solubility product constant.

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