Enthalpy of neutralization of oxalic acid is $-25.4\text{ kcal/mol}$ using strong base $NaOH$ . Enthalpy change for the process $H_2{C}_2{O}_4\left(aq\right)\to 2H^{+}\left(aq\right)+C_2{O}_4^{2-}\left(aq\right)$ is about