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### Topic: Equilibrium constant  (Read 1167 times)

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#### zmasterflex

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##### Equilibrium constant
« on: March 04, 2014, 02:40:56 PM »
What is the relationship between the equilibrium constant of a reaction (Kc) and the rate constants for the forward (Kf) and reverse reactions (Kr)?

If the law of mass action = Q = Kc = products/reactants, then the answer should presumably be Kc = Kr/Kf.. Answer given is Kc=Kf/Kr Why?
thanks

#### Kate

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##### Re: Equilibrium constant
« Reply #1 on: March 04, 2014, 03:49:08 PM »
This has to do with kinetics or, better yet, with the relationship between thermodynamics and kinetics.

Suppose you have the reaction C D

Then,

vf = kf[C]

vr = kr[D]

At equilibrium, vf = vr, so kf[C] = kr[D]

Since [D]/[C] = Kc, then kf/kr = Kc