1 Physics -- First Law of Thermodynamics

What is molar heat capacity of gas? Why is the molar heat capacity at constant pressure more that constant volume?

What is molar heat capacity of gas? Why is the molar heat capacity at constant pressure more that constant volume?

The amount of heat required to change the temperature of 1 mole of gas through 1 K is defined as molar heat capacity of the gas.


From First Law of Thermodynamics,

dQ = dU + dW

At constant volume, dW = 0. But it is not 0 at constant pressure. Hence, more heat has to be supplied to bring the same change in the internal energy of the gas. Therefore, the molar heat capacity at constant pressure is more than that at constant volume.

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