Oxygen pressure for oxidizing gold problem

[Sarahchemmy]

Hi Guys! I'm not sure what to do, I don't epect anyone to complete this for me (not that i'd be adverse to it) but can anyone give me some guidance please?

The question is linked: http://imgur.com/0cXlnkB

2AU(solid) + 3/2O2(gas) <--> Au203(solid)

@25degrees.

Gibbs free energy change = +78.7kj/kmol.

Estimate the value of oxygen pressure required oxidizing gold Is the reaction spontaneous in air?

Do I use aA + bB -> cC + dD? if so I'm not sure what to use for each value?

Thanks!

 

[Sarahchemmy]

So so far my method has been;

0 = deltaG + RTlnP/Po

To eventually get a pressure of 726.75mmhg

To which I divided by the stoichiometry (3/2 02) to get 484.5mmhg
Converting to bar to get 0.653bar

This yields the partial pressure for 02?

 

[Sarahchemmy]

bump?