Calculate delta G with partial pressure

[annfreakinpark]

Consider the reaction 2 NO2(g)--> N2O4(g).

Calculate ΔG at 298 K if the partial pressures of NO2 and N2O4 are 0.30 atm and 1.65 atm, respectively.


I know that I have to convert the atm to moles using the ideal gas law. But how can I find the moles without the volume?

Please help!

[kingchemist]

Kp = ppN2O4/(ppNO2)² = 1.65/0.30²

You can work out mole fraction from partial pressure.
Mole fraction NO2 = 0.30/(0.30+1.65)
Mole fraction N2O4 = 1.65/(0.30+1.65)

This will give the ratio of moles