Thermal Expansion of Gas:
Gases expand on heating and contract on cooling like solids and liquids. Like liquids, gases don’t have any fixed shape and therefore the linear or the surface expansion of a gas is irrelevant. Only the change in volume with the change in temperature is of importance.
Characteristics of Expansion of Gas:
1. Coefficient of volume expansion for gas has a much higher value than for solids and liquids. For a certain rise in temperature, the expansion of the container is negligible compared to the expansion of the gas in it. Hence, the apparent expansion of gas is practically the same as real expansion and is usually not reckoned separately unless a very high accuracy is required.
2. Unlike solids and liquids, the volume of a fixed mass of a gas is considerably affected due to any change in pressure. So, the effects of both temperature and pressure have to be studied in connection with the expansion or contraction of a gas. While studying the effect of one, the other is usually kept constant.
3. The rate of expansion or contraction, due to the change in either pressure or temperature doesn’t differ for different gases. Unlike solids and liquids, the coefficient of expansion is the same for all gases.