Strong and Weak Acids

Remember strong acids and Bases completely ionise and therefore the concentration of H⁺ or OH^- ions respectively can be easily seen and the pH calculated. PH = log 1/[H⁺] and

 Kw = [H⁺] [OH^-] = 1.0 x 10^-14 at 25⁰C (Note this increases at higher temperatures and decreases at lower temperatures). You should be able to explain why. This does not mean that hot water is acidic!! It’s neutral as [H⁺] = [OH^-], but the pH will be less than 7. PH 7 only means neutral at 25⁰C

Weak acids and Bases only partially ionise and therefore, you cannot use the initial concentration alone in order to determine the concentration of H⁺ or OH^- ions, you need to have the Ka or Kb values.

Weak/Strong Acids and Bases

The Ionic Product of Water