For a dimerization reaction, 2 A ( g ) → A_2( g ), at 298 K, Δ U^ =-20 kJ mol^-1, Δ S^ =-30 J K^-1 mol^-1, then the Δ G^ will be \ \ \ \ J.

For a dimerization reaction, $\displaystyle 2 \mathrm{~A}(\mathrm{~g}) \rightarrow \mathrm{A}_2(\mathrm{~g})$, at $\displaystyle 298 \mathrm{~K}, \Delta \mathrm{U}^{\ominus}=-20 \mathrm{~kJ} \mathrm{~mol}^{-1}, \Delta \mathrm{~S}^{\ominus}=-30$ $\displaystyle \mathrm{J} \mathrm{K}^{-1} \mathrm{~mol}^{-1}$, then the $\displaystyle \Delta \mathrm{G}^{\ominus}$ will be \_\_\_\_ J.