CAIE A Level Chemistry 9701 · States of matter
A cyclist pumps extra air into a bicycle tyre with a hand pump. The air in the tyre exerts a pressure on the inner surface of the tyre, and the pressure increases as more air is pumped in.
(a) Describe the origin of this pressure in terms of the behaviour of the air molecules in the tyre.
(b) Real gases are often modelled as ideal gases. Describe the two assumptions made about an ideal gas that concern the volume of its particles and the forces between particles.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.