(a) Define two principle specific heats of gases.
(b) Why Cp is greater than Cv?
(a) Specific heat at constant volume:
The quantity of heat required to raise the temperature of 1 mole of gas through 1°C at constant volume is known as specific heat at a constant volume.
Specific heat at constant pressure:
The quantity of heat required to raise the temperature of 1 mole of gas through 1°C at constant pressure is called specific heat at constant pressure.
(b) When gas is heated at constant volume, the whole of the heat supplied is used to increase the temperature of gas because gas is not allowed to expand and work done against expansion is zero.
When gas is heated at a constant pressure, it expands, and gas has to do work against the external pressure.
Therefore, in addition to the heat which is required to raise the temperature, heat is also required to expand the gas. So, at constant pressure, we require more heat than at constant volume.
