DP Chemistry (last assessment 2024)

Question 19N.2.sl.TZ0.6a(iv)

Date	November 2019	Marks available	[Maximum mark: 2]	Reference code	19N.2.sl.TZ0.6a(iv)
Level	sl	Paper	2	Time zone	TZ0
Command term	Suggest	Question number	a(iv)	Adapted from	N/A

a(iv).

[Maximum mark: 2]

19N.2.sl.TZ0.6a(iv)

Automobile air bags inflate by a rapid decomposition reaction. One typical compound used is guanidinium nitrate, C(NH₂)₃NO₃, which decomposes very rapidly to form nitrogen, water vapour and carbon.

(a(iv))

Suggest why water vapour deviates significantly from ideal behaviour when the gases are cooled, while nitrogen does not.

[2]

Markscheme

Any two of:
nitrogen non-polar/London/dispersion forces AND water polar/H-bonding ✔
water has «much» stronger intermolecular forces ✔
water molecules attract/condense/occupy smaller volume «and therefore deviate from ideal behaviour» ✔

Syllabus sections

Core

Core » Topic 4: Chemical bonding and structure » 4.4 Intermolecular forces

Core » Topic 1: Stoichiometric relationships » 1.3 Reacting masses and volumes

Core » Topic 1: Stoichiometric relationships

Core » Topic 4: Chemical bonding and structure

Question 19N.2.sl.TZ0.6a(iv)

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Syllabus sections

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