Calculate the pH of 0.200 mol dm–3 potassium hydroxide

Answer 1

KOH (aq) → K⁺ (aq) + OH^- (aq)

Since KOH is a strong base, it will undergo 100% ionization and will exist in solution as K⁺ and OH^- ions. This means that the concentration of OH^- will = 0.200 mol dm^-3.

Calculate the pOH using the equation

pOH = - log [OH^-] = - log 0.200 = 0.70

pOH and pH are related by the equation

pH + pOH = 14.00

Rearrange to solve for the pH

pH = 14.00 - 0.70 = 13.30