Question

K_w = 1 x 10^-14 at 25°C. Justify this statement.

Answer 1

1. Experimentally found that the concentration of H₃O in pure water is 1 x 10^-7 at 25°C.

2. Since the dissociation of water produces equal number of H₃O₄ and OH^- , the concentration of OH^- is also equal to 1 x 10^-7 at 25°C. The ionic product of water at 25°C is

K_w = [H₃O⁺] [OH^-]

= [1 x 10^-7] [1 x 10^-7]

K_w = [1 x 10^-14]