Physics Help Forum Oxygen pressure for oxidizing gold problem

 Nov 23rd 2016, 06:21 AM #1 Junior Member   Join Date: Nov 2016 Posts: 2 Oxygen pressure for oxidizing gold problem 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! Last edited by Sarahchemmy; Nov 23rd 2016 at 06:45 AM. Reason: Broken link
 Nov 23rd 2016, 09:30 AM #2 Senior Member     Join Date: Jun 2016 Location: England Posts: 618 The main thrust of the problem posed seems to be altering the balance point of the reversible reaction by increasing the concentration of one of the reactants (the oxygen). I can vaguely remember (from my brief foray into chemistry many moons ago) that the Gibbs free energy is important in the determination of this sort of thing. But that is about as far as I can go. You might get a better response from: Chemistry Help Forum
 Nov 24th 2016, 04:56 AM #3 Junior Member   Join Date: Nov 2016 Posts: 2 Thanks I've sent a message over there too. 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?

 Tags gold, oxidizing, oxygen, pressure, problem

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