DP Chemistry (first assessment 2025)

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Question 19N.1A.HL.TZ0.27

Date	November 2019	Marks available	[Maximum mark: 1]	Reference code	19N.1A.HL.TZ0.27
Level	HL	Paper	1A	Time zone	TZ0
Command term	Apply	Question number	27	Adapted from	N/A

27.

[Maximum mark: 1]

19N.1A.HL.TZ0.27

Which can act as a Lewis acid but not a Brønsted–Lowry acid?

A. BF₃

B. H₂O

C. NF₃

D. NH₃

[1]

Markscheme

A

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.