DP Chemistry (last assessment 2024)

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Question 18M.2.hl.TZ1.5d

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

Limescale, CaCO3(s), can be removed from water kettles by using vinegar, a dilute solution of ethanoic acid, CH3COOH(aq).

(d)

Determine the pH of 0.010 mol dm−3 2,2-dimethylpropanoic acid solution.

Ka (2,2-dimethylpropanoic acid) = 9.333 × 10−6

[2]

Markscheme

[H+] « = K a × [ C 5 H 10 O 2 ] = 9.333 × 10 − 6 × 0.010   » = 3.055 × 10–4 «mol dm–3»

«pH =» 3.51

 

Accept “pH = 3.52”.

Award [2] for correct final answer.

Accept other calculation methods.

[2 marks]

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