Standard reaction heat capacity, Kirchhoff

The temperature variation of the standard reaction enthalpy is given by Kirchhoff s law, Eq. 23, in terms of the difference in molar heat capacities at constant pressure between the products and the reactants. 

Kirchhoff s law The relation between the standard reaction enthalpies at two temperatures in terms of the temperature difference and the difference in heat capacities (at constant pressure) of the products and reactants. 

If the temperature dependence of the standard enthalpy of reaction cannot be neglected, it can be taken into account using the molar heat capacities as in the case of typical chemical reactions (KirchhofFs law). 

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