Catholic High Prelims 2004 P2 Q5
The figure below shows a metal can with a tight fitting lid. The can is heated.
Use the simple kinetic theory of gases to answer the following:
(a) What happens to the pressure in the can when the temperature increases?
(b) If a little water is put into the bottom of the can before heating, explain how this would affect the pressure in the can when the temperature increases?
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Answer:
(a) The pressure increases since the molecules gain kinetic energy and move faster, making more collisions per unit area per second with the walls of the container.
(b) The pressure would be greater as there will be more gas molecules due to the vapourisation of water. In the can, there will thus be higher frequency of collisions per unit area of the walls, and this results in the higher pressure.
