Strong vs Weak Bases: What's the Difference?
Everyone learns "NaOH is strong, ammonia is weak" and then hits a question about 0.010 M NaOH versus 6 M ammonia and freezes. Which one has the higher pH? The answer needs the difference between strength and concentration — and this is the pair of words that decides it. The short answer: a strong base produces hydroxide ions essentially completely in water, so its OH⁻ concentration equals its concentration. A weak base only partly reacts, sitting at an equilibrium described by Kb , so its OH⁻ concentration is far lower than its concentration. Quick comparison at a glance Feature Strong base Weak base Behaviour in water Reacts/dissociates essentially completely Partly reacts; equilibrium Arrow used Single, → Double, ⇌ Kb Not applicable — it dissociates, it does not equilibrate with water Small and measurable [OH⁻] ≈ the base's concentration Much less than its concentration Typical pH of 0.10 M 13.0 ~11.1 Examples NaOH, KOH, Ba(OH)₂...