Mayer’s relation : Cp – Cv = R. Let M0 = molar mass of the gas, Sp = specific heat of the gas at constant pressure and Sv = specific heat of the gas at constant volume.
Now, Cp = M0Sp and Cv = M0Sv
∴ M0Sp – M0Sv = R
∴ Sp – Sv = \(\frac{R}{M_0}\) when heat and work are expressed in the same units. If heat is expressed in calorie or kilo calorie and work is expressed in erg or joule, we get,
Sp – Sv = \(\frac{R}{M_0j}\) , where J is the mechanical equivalent of heat.
