Q. Show Equilibrium expression for water?

Ans.

The equilibrium expression for water is equal to a constant, Kw. This constant is called the ion product of water and is equal to 1.0 x 10^-14:

K_w = [H⁺] [OH^-] = 1.0 -> 10^-14

There are two equilibrium constants, Ka and Kb, which are useful in describing the strength of acids and bases.

Suppose H-A and B-OH are an acid and base, respectively. Then Ka and Kb are defined as follows:

H-A -> H⁺ + A- Ka = [H⁺] [A^-] / [H-A]

B-OH -> B⁺ + OH- Kb = [B⁺] [OH^-] / [B-OH]

The higher Ka or Kb is, the greater the degree of ionization by the acid or base.