At $1500^{\circ} \mathrm{C}, K_{\mathrm{c}}=5.67$ for the reaction
$$
\mathrm{CH}_{4}(g)+\mathrm{H}_{2} \mathrm{O}(g) \rightleftharpoons \mathrm{CO}(g)+3 \mathrm{H}_{2}(g)
$$
Calculate the value of $\Delta G_{1773}^{\circ}$ for the reaction at this temperature.