Question

Potassium hydrogen sulphite is mixed with distilled water to form 0.45 M solution. What is concentration of hydronium ions?

Answer 1

Potassium hydrogen sulphite(KHSO3) is dissociated into ions when mixed with water

KHSO3 -------------> K+(aq) + HSO3-(aq)

HSO3-(aq) + H2O <-------------> H3O+(aq) + SO3^2-(aq)   : Kb = 6.25 x 10^-13 ( obtained from Ka of H2SO3)

Let the concentration of H3O+ be x,

=> [H3O+] = x , [SO3^2-] = x,

Kb = x^2 / (0.45-x)

6.25 x 10^-13 = x^2 / (0.45-x)

Solve for 'x' by using quadratic equation,

=> x = 5.3 x 10^-7

=> [H3O+] = 5.3 x 10^-7 <<<<<<-------------(ANSWER)