CAIE A-Level Chemistry 4.1.2 Ideal-Gas Particle Model
Practise stating the negligible-volume and no-attraction assumptions and predicting when real gases approach ideal behaviour.
- Syllabus
- 2028–2030
- Course
- Chemistry 9701
- Level
- AS
Exam points
- treat ideal-gas particles as having negligible volume compared with the container
- assume no intermolecular attractions or repulsions except during elastic collisions
- predict most ideal behaviour at low pressure and high temperature and explain deviations when assumptions fail
4.1.2—Ideal gases have zero particle volume and no question 1
[Maximum number: 4]
The strength of interaction between particles determines whether the substance is a solid, liquid or gas at room temperature.
Question (a)
(a)
Nitrogen, N2, is also a gas at room temperature and pressure. Neither CO nor N2 is an ideal gas.
[ 4 ]
Question (i)
(i)
State two assumptions that are made about the behaviour of particles in an ideal gas.
1
2
[ 2 ]
Any two assumptions about the behaviour of particles in an ideal gas from
- (particles / molecules have mass but) negligible size / volume (compared to total volume of gas / container)
- no / negligible forces / interactions (between particles / molecules)
- collisions are elastic
Question (ii)
(ii)
Explain why N2 does not behave as an ideal gas at very high pressures.
[ 2 ]
M1 IMF become larger / more significant
M2 volume of molecules / particles becomes significant / no longer negligible
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