DP Chemistry (first assessment 2025)

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Question 19N.2.HL.TZ0.a

Date	November 2019	Marks available	[Maximum mark: 2]	Reference code	19N.2.HL.TZ0.a
Level	HL	Paper	2	Time zone	TZ0
Command term	Annotate, Show	Question number	a	Adapted from	N/A

a.

[Maximum mark: 2]

19N.2.HL.TZ0.a

A sample of ethanoic acid was titrated with sodium hydroxide solution, and the following pH curve obtained.

Annotate the graph to show the buffer region and the volume of sodium hydroxide at the equivalence point.

[2]

Markscheme

buffer region on graph ✔
equivalence point/V_eq on graph ✔

NOTE: Construction lines not required.

Syllabus sections

Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.1—Proton transfer reactions » Reactivity 3.1.13—pH curves of different combinations of strong and weak monoprotic acids and bases have characteristic shapes and features. Interpret the general shapes of pH curves for all four combinations of strong and weak acids and bases.