Molar heat capacity at constant P for a substance is equal to:

Heat capacity is the amount of heat added to a substance to raise its temperature by one kelvin. Hence, at constant pressure, the molar heat capacity is given by the ratio (∂T∂H​)_P.​

${\mathrm{C}}_{\mathrm{p}}=\frac{{\mathrm{Q}}_{\mathrm{p}}}{∆\mathrm{T}}=\frac{∆\mathrm{H}}{∆\mathrm{T}}or{\left(\frac{\mathrm{\delta H}}{\mathrm{\delta T}}\right)}_{\mathrm{p}}$