Question

If two reactions sum to an overall reaction, and the equilibrium constants for the two reactions are K1K1 and K2K2, what is the equilibrium constant for the overall reaction?

Answer 1

Answer: The equilibrium constant for the overall reaction is $K_1\times K_2$

Explanation:

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios.

a) $A\rightarrow B+C$

$K_1=\frac{[B]\times [C]}{[A]}$

b) $B+C\rightarrow D$

$K_2=\frac{[D]}{[B]\times [C]}$

For overall reaction on adding a and b we get c

c) $A\rightarrow D$

$K_3=\frac{[D]}{[A]}$

$K_3=K_1\times K_2=\frac{[B]\times [C]}{[A]}\times \frac{[D]}{[B]\times [C]}$

$K_3=K_1\times K_2=\frac{[D]}{[A]}$

The equilibrium constant for the overall reaction is $K_1\times K_2$