Heat Capacity at Constant P and Maier-Kelley Functions

a Heat Capacity at Constant P and Maier-Kelley Functions 

As we have already seen, the heat capacity is the amount of heat that must be furnished to raise the temperature of a given substance by 1 K at the T of interest. If constant pressure is maintained during heat transfer, heat capacity is defined as heat capacity at constant P (Cp). As already seen in chapter 2, Cp is the partial derivative of the enthalpy of the substance at constant P and composition—i.e.. 

If heat transfer takes place at constant volume, the magnitude is defined as heat capacity at constant volume (Cy) and is equivalent, as we have seen, to the partial derivative of the internal energy of the substance at constant volume and composition  

We have seen in chapter 2 that the heat capacity at constant P is of fundamental importance in the calculation of the Gibbs free energy, performed by starting from the standard state enthalpy and entropy values 

With increasing T, Cp, like Cy, approaches a limit imposed by the Dulong and Petit rule  

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