DP Chemistry (first assessment 2025)

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Question 23M.2.HL.TZ1.5b

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Date May 2023 Marks available [Maximum mark: 2] Reference code 23M.2.HL.TZ1.5b
Level HL Paper 2 Time zone TZ1
Command term Calculate Question number b Adapted from N/A
b.
[Maximum mark: 2]
23M.2.HL.TZ1.5b
(b)

The Ksp of copper (II) hydroxide is 2.2 × 10−20. Calculate the molar solubility of Cu2+ (aq) ions in a solution of pH 9.

[2]

Markscheme

Ksp =[Cu2+][OH−]2
OR
2.2 × 10−20 =[Cu2+] × (10−5)2 ✓

[Cu2+] «= Ksp/[OH−]2 =2.2 x 10−20/(10−5)2»
= 2.2 ×10−10«mol dm−3» ✓


Award [2] for correct final answer.