Question

calculate delta G at 298 K when 5.0 atm H2 and 3.0 atm of CO2 are converted to methanol.

Answer 1

I may have stared at the sun too long today but why isn't dG = 0 when the reaction has reached equilibrium? You can calculate those concentrations if you wish AND you can calculate Kp at 25C with dGo = -RTlnK. But I don't think any of that is necessary since we know dG = 0 at equilibrium. And the problems says WHEN CO2 and H2 are converted which means AFTER the reaction to me.
.........CO2 + 3H2 ==> CH3OH + H2O
I........ 5.....3........0......0
C........-p....-p........p......p
E........5-p...3-p.......p......p
Calculate p after you know Kp if you really need to know those pressures.