According to the Mayer’s relation or the Mayer’s formula the difference between these two heat capacities is equal to the universal gas constant, thus the molar specific heat at constant pressure is equal:
Cp = Cv + R
Julius Robert Mayer, a German chemist and physicist, derived a relation between specific heat at constant pressure and the specific heat at constant volume for an ideal gas. He studied the fact that the specific heat capacity of a gas at constant pressure (Cp) is slightly greater than at constant volume (Cv). He reasoned that this Cp is greater than the molar specific heat at constant volume Cv, because energy must now be supplied not only to raise the temperature of the gas but also for the gas to do work because in this case volume changes.