DP Chemistry (last assessment 2024)

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Question 21M.2.sl.TZ1.b(ii)

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Date May 2021 Marks available [Maximum mark: 1] Reference code 21M.2.sl.TZ1.b(ii)
Level sl Paper 2 Time zone TZ1
Command term Demonstrate Question number b(ii) Adapted from N/A
b(ii).
[Maximum mark: 1]
21M.2.sl.TZ1.b(ii)

Iron (II) sulfide reacts with hydrochloric acid to form hydrogen sulfide, H2S.

In aqueous solution, hydrogen sulfide acts as an acid.

Saturated aqueous hydrogen sulfide has a concentration of 0.10 mol dm−3 and a pH of 4.0. Demonstrate whether it is a strong or weak acid.

[1]

Markscheme

weak AND strong acid of this concentration/[H+] = 0.1 mol dm−3 would have pH = 1
OR
weak AND [H+] = 10−4 < 0.1 «therefore only fraction of acid dissociated» ✔

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