Chemistry - Thermochemistry Question with Solution | TestHub

One equivalent of oxalic acid gives two moles of ${\mathrm{H}}^{+}$ ions, as the basicity of the acid is two.

Now enthalpy of neutralisation is defined for one equivalent of acid as well as base.

For weak acids:

Enthalpy of neutralisation$=$Basicity$\times$enthalpy of neutralisation for strong acid and base$+$enthalpy of dissociation

Thus, enthalpy of dissociation for oxalic acid$=\left(-25\right)-\left(2\times -13.7\right)=27.4-25=2.4 \mathrm{kcal} {\mathrm{mol}}^{-1}$