DP Chemistry (first assessment 2025)

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Question 19M.1A.HL.TZ1.26

Date	May 2019	Marks available	[Maximum mark: 1]	Reference code	19M.1A.HL.TZ1.26
Level	HL	Paper	1A	Time zone	TZ1
Command term		Question number	26	Adapted from	N/A

26.

[Maximum mark: 1]

19M.1A.HL.TZ1.26

Which is a Lewis acid but not a Brønsted−Lowry acid?

A. AlCl₃

B. CH₃CO₂H

C. HF

D. CCl₄

[1]

Markscheme

A

Examiners report

Identifying a Lewis acid seemed relatively easy for the majority of candidates.

Syllabus sections

Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.4—Electron-pair sharing reactions » Reactivity 3.4.6—A Lewis acid is an electron-pair acceptor and a Lewis base is an electron-pair donor. Apply Lewis acid–base theory to inorganic and organic chemistry to identify the role of the reacting species.