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Strong vs Weak Bases

Chemistry: Edexcel IGCSE, topic 12.1.13

Strong vs Weak Bases

Bases are metallic oxides or hydroxides (or ammonia) that neutralise acids to form salt and water. There are two types: soluble and insoluble bases. An alkali is a soluble base - one that dissolves in water.

Strong base

Strong base

  • Aqueous sodium hydroxide and potassium hydroxide are examples of strong bases.
  • Strong bases fully ionise in aqueous solutions.
  • NaOH(aq) → Na+(aq) + OH-.
  • KOH(aq) → K+(aq) + OH-.
Weak base

Weak base

  • Weak bases don't fully ionise in aqueous solutions.
  • Ammonia solution is an example of a weak base.
  • It exists mainly as NH3 molecules. Only a few of these react with water molecules to form ions.
  • NH3(aq) + H2O(l) ⇌ NH4+(aq) + OH-(aq).

Test yourself on Strong vs Weak Bases

  • Which of these are examples of strong bases?

  • Which of the following is a weak base?

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