Consider the following reversible reaction. mc030-1.jpg what is the equilibrium constant expression for the given system?

Since you have not included the given reaction, I am going to explain you how to solve these kind of problems.

1) The chemical equilibrium is a dynamic process. It means that in an equilibrim reaction there are two rectaions, the forward reaction and the reverse reaction whose velocities are the same.

2) The general equation of a a chemical reaction in equlibrium is:

aA + bB ⇄ cC + dD
Where A and B are the reactants, C and D are the products, and a, b, c, d, are the coefficientes in the balanced equation.

3) So, the equilibrium law is:



Where Keq is the constant of equilibrium

4) To complete the explanation, I am going to deal with an example:

i) Consider the equlibrium reaction between hydrogen and iodine:

H₂ (g) + I₂(g)   ⇄  2HI(g)

ii) The forward reaction is H₂ (g) + I₂(g)   →  2HI(g)

iii) The reverse reaction is 2HI (g) → H₂ (g) + I₂(g)

iv) The law of equilibrium is: