[zmasterflex]

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]

This has to do with kinetics or, better yet, with the relationship between thermodynamics and kinetics.

Suppose you have the reaction C D

Then,

v_f = k_f[C]

v_r = k_r[D]

At equilibrium, v_f = v_r, so k_f[C] = k_r[D]

Since [D]/[C] = K_c, then k_f/k_r = K_c