For a gaseous reaction standard conditions are 298 K and a p

For a gaseous reaction, standard conditions are 298 K and a partial pressure of 1 atm for all species. For the reaction

C2H6(g)+H2(g) <--> 2CH4

the standard change in Gibbs free energy is ?G

?G = ?Go + R*T*ln(Q)

Q = ((a_CH4)^2)/(a_C2H6) * a_SO2)=(.700)^2/(.400*0.150)=8.166

?G=-32.8+ 8.3145 J/(mol*K)*298*ln(8.166)

=-32.8+ 8.3145 J/(mol*K)*298*2.0999

=-32.8+5.200=-27.59