From the following data, $$ \begin{array}{c} \mathrm{C} \text { (graphite)
}+\mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}(g) \\ \Delta
H_{\mathrm{rxn}}^{\circ}=-393.5 \mathrm{~kJ} / \mathrm{mol} \\\
\mathrm{H}_{2}(g)+\frac{1}{2} \mathrm{O}_{2}(g) \longrightarrow \mathrm{H}_{2}
\mathrm{O}(l) \\ \Delta H_{\mathrm{rxn}}^{\circ}=-285.8 \mathrm{~kJ} /
\mathrm{mol} \\ 2 \mathrm{C}_{2} \mathrm{H}_{6}(g)+7 \mathrm{O}_{2}(g)
\longrightarrow 4 \mathrm{CO}_{2}(g)+6 \mathrm{H}_{2} \mathrm{O}(l) \\ \Delta
H_{\mathrm{rxn}}^{\circ}=-3119.6 \mathrm{~kJ} / \mathrm{mol} \end{array} $$
calculate the enthalpy change for the reaction $$ 2 \mathrm{C}(\text {
graphite })+3 \mathrm{H}_{2}(g) \longrightarrow \mathrm{C}_{2}
\mathrm{H}_{6}(g) $$