Calculate the value of the equilibrium constant k for the reaction A+B=C

Question

Calculate the value of the equilibrium constant K for the reaction

A+B=C

from the following information:

3C=D (Kc=7.9*10^-4)

D=3A+3B (Kc= 6.7*10^-2)

note the equal sign is the forward/reverse sign

Answer 1

For the equilibrium equation  A + B = C      the equilibrium constant  k = [A][B]/[C]

 

3C = D       k1 = [D]/[C]^3 = 7.9*10^-4

 

D = 3A + 3B     k2 = [A] ^3/[B]^3    = 6.7*10^-2

 

k1 x k2 = [A]^3 [B]^3 / [C]^3  = {[A][B]/[C]} ^3

 

Substitute and solve for k.