I'm trying to understand this: http://en.wikipedia.org/wiki/Equilibrium_constant#Derivation_from_Gibbs_Free_Energy And there are few steps that I don't get. My first question is probably a stupid one, but where does the [tex]\Sigma[/tex]v[tex]_{j}[/tex]A[tex]_{j}[/tex]=0 come from? What exactly is it summing up, the number of atoms? Are you assuming that the products side is negative? (Because I don't see how else you would get zero) And why does it only go up to n? I'll ask my other questions after I get some replies because it's possible I'll figure them out after I read the replies.
Ok, but why does it only sum up to n? The first equation in the derivation shows the first product being n but then shows more products after that. If it was mass conservation, wouldn't it have to sum passed n?