Mayflower Sec Sem 1 2005 P2 Q3
Using the kinetic model of matter for part (a) and (b),
(a) Explain how gases exert pressure.
(b) Explain how the pressure exerted by a gas changes when its volume is increased.
(c) A carbon dioxide cylinder contains gas at a pressure of 4.5 * 105 Pa. The volume of the cylinder is 0.015 m3.
Calculate the volume occupied by the gas at atmospheric pressure, 1.5 * 105 Pa.
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Answer:
(a) Gas molecules move randomly, and they bombard the walls of the container they are in. During the bombardment, the gas molecules exert a force on the walls. The force per unit area on the walls from the bombardment of these gas molecules is the pressure exerted by the gas on the wall.
(b) When volume is increased, the pressure decrease. This is because although the number of gas molecules remain the same, the frequency of collisions with the walls of the container decreases. This results in a decrease in pressure.
(c) P1V1 = P2V2
(4.5 * 105) (0.015) = (1.0 * 105) * V2
V2 = 0.0675
Thus, the volume occupied by the gas at a.t.m. is 0.0675 m³
