Why divide Kfwd and Krev to find Keq?

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Why divide Kfwd and Krev to find Keq?

Postby Chem_Mod » Sun Oct 02, 2011 2:14 am

Why is it k(forward) divided by k(reverse) when finding Keq? Why wouldn't it be the other way around since Keq is products divided by reactants (therefore, k-reverse divided by k-forward)? (Q4A, 2nd spring midterm)

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Re: Why divide Kfwd and Krev to find Keq?

Postby Chem_Mod » Sun Oct 02, 2011 2:14 am

Keq = [products]/[reactants] is only for concentrations, not rate constants. On this question, Keq = k(forward)/k(reverse) because k(forward) is the rate constant for the formation of products, while k(reverse) is the rate constant for the formation of reactants. Since rate = k*concentration, k and concentration are inversely related. This derivation can be found on Bruice p. 134.


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