Hi all,
I was wondering if you have any idea about how to find the equilibrium constant of a reaction while the only available data is standard Gibbs from tables, which means, there is no data regarding Gibbs free energy in the reaction condition itself. Help me please to reach an idea, i would kindly appreciate it, thanks a lot.
Best Regards, thanks in advance
Reza
A reaction is composed of reactants and products. Let us consider a reaction
A+B=C+D
If you know the value of Gibbs free energy for compounds A, B C and D , the gibbs free energy of reaction is calculated. and the solubility equilibrium is
Log(K)= - DG°reaction/ (R*T*ln(10))
If you write the mass action law
Q = C* D/ (A*B) where A,B,C and D are activity coefficient that can be measured (in solution)
Q is the apparent equilibrium and should be compared with the equilibrium constant K
so if QK solution over saturated
A reaction is composed of reactants and products. Let us consider a reaction
A+B=C+D
If you know the value of Gibbs free energy for compounds A, B C and D , the gibbs free energy of reaction is calculated. and the solubility equilibrium is
Log(K)= - DG°reaction/ (R*T*ln(10))
If you write the mass action law
Q = C* D/ (A*B) where A,B,C and D are activity coefficient that can be measured (in solution)
Q is the apparent equilibrium and should be compared with the equilibrium constant K
so if QK solution over saturated
Because at equilibrium the change in Gibbs free function is zero and what you have left is only the standard Gibbs free function.
Thanks alot for your comments, now I understand for only equilibrium situation, I can find my Quotient factor (= Keq) by having standard GFE, But, if there is no equilibrium and I dont have the concentrations of my products, how can I find the Quotient??? I mean, I dont have concentrations of products and also I dont have the GFE of them, because As I think, tables and softwares like EES they give us standard values , am I right?
Thanks in advance
Reza
Eqiulibrium constant is defined only when you have an equilibrium. Also, you must know the concentrations of the product. The standard Gibbs free function can also be calculated from the Gibbs function of formation.
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