The enthalpy of neutralisation of oxalic acid by a strong base is$-25.4 \mathrm{kcal} {\mathrm{mol}}^{-1}$. The enthalpy of neutralisation of strong acid and strong base is $-13.7 \mathrm{kcal} {\mathrm{equiv}}^{-1}$. The enthalpy of dissociation of ${\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4\rightleftharpoons 2{\mathrm{H}}^{+}+ {\mathrm{C}}_2{\mathrm{O}}_4^{2-}$ is

The following two reactions are known: ${\mathrm{Fe}}_2{{\mathrm{O}}_3}_{\left(\mathrm{s}\right)}+3{\mathrm{CO}}_{\left(\mathrm{g}\right)}\to 2{\mathrm{Fe}}_{\left(\mathrm{s}\right)}+3{{\mathrm{CO}}_2}_{\left(\mathrm{g}\right)}; ∆\mathrm{H}=-26.8\mathrm{kJ}$ and${\mathrm{FeO}}_{\left(\mathrm{s}\right)}+{\mathrm{CO}}_{\left(\mathrm{g}\right)}\to {\mathrm{Fe}}_{\left(\mathrm{s}\right)}+{{\mathrm{CO}}_2}_{\left(\mathrm{g}\right)}; ∆\mathrm{H}=-16.5\mathrm{kJ}$. The value of $∆\mathrm{H}$ for the following reaction ${\mathrm{Fe}}_2{{\mathrm{O}}_3}_{\left(\mathrm{s}\right)}+{\mathrm{CO}}_{\left(\mathrm{g}\right)}\to 2{\mathrm{FeO}}_{\left(\mathrm{s}\right)}+{{\mathrm{CO}}_2}_{\left(\mathrm{g}\right)}$ is

Given:

$$\begin{gathered} {\mathrm{NH}}_3\left(\mathrm{g}\right)+3{\mathrm{Cl}}_2\left(\mathrm{g}\right)\rightleftharpoons {\mathrm{NCl}}_3\left(\mathrm{g}\right)+3\mathrm{HCl}(\mathrm{g} ); -∆{\mathrm{H}}_1 \\ {\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)\rightleftharpoons 2{\mathrm{NH}}_3\left(\mathrm{g}\right); -∆{\mathrm{H}}_2 \\ {\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{Cl}}_2\left(\mathrm{g}\right)\rightleftharpoons 2\mathrm{HCl}\left(\mathrm{g}\right); ∆{\mathrm{H}}_3 \end{gathered}$$

The heat of formation of ${\mathrm{NCl}}_3\left(\mathrm{g}\right)$ in terms of $∆{\mathrm{H}}_1$, $∆{\mathrm{H}}_2$, and $∆{\mathrm{H}}_3$ is