DP Chemistry (first assessment 2025)

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Question 20N.1A.HL.TZ0.26

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.1A.HL.TZ0.26
Level	HL	Paper	1A	Time zone	TZ0
Command term	Apply	Question number	26	Adapted from	N/A

26.

[Maximum mark: 1]

20N.1A.HL.TZ0.26

Which species is a Lewis acid but not a Brønsted–Lowry acid?

A. ${Cu}^{2 +}$

B. ${NH}_{4}^{+}$

C. $Cu$

D. ${CH}_{3} COOH$

[1]

Markscheme

A

Examiners report

Vast majority of candidates understood the difference between Lewis and Brønsted Lowry acids.

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.

Reactivity 3. What are the mechanisms of chemical change? » Reactivity 3.1—Proton transfer reactions » Reactivity 3.1.1—Brønsted–Lowry acid is a proton donor and a Brønsted–Lowry base is a proton acceptor. Deduce the Br.nsted–Lowry acid and base in a reaction.