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Question 18N.2.hl.TZ0.6c

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Date November 2018 Marks available [Maximum mark: 3] Reference code 18N.2.hl.TZ0.6c
Level hl Paper 2 Time zone TZ0
Command term Sketch Question number c Adapted from N/A
c.
[Maximum mark: 3]
18N.2.hl.TZ0.6c

Butanoic acid, CH3CH2CH2COOH, is a weak acid and ethylamine, CH3CH2NH2, is a weak base.

(c)

Sketch the pH curve for the titration of 25.0 cm3 of ethylamine aqueous solution with 50.0 cm3 of butanoic acid aqueous solution of equal concentration. No calculations are required.

[3]

Markscheme

decreasing pH curve ✔

pH close to 7 (6–8) at volume of 25 cm3 butanoic acid ✔

weak acid/base shape with no flat «strong acid/base» parts on the curve ✔

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