Neutralisation
Year 8 🧪 Acids, Bases & Salts Describe acid + base → salt + water; write neutralisation equations.
⚗️ Neutralisation
Neutralisation occurs when an acid reacts with a base to form a salt and water. H⁺ ions combine with OH⁻ ions.
General Equation
$$\text{acid} + \text{base} \rightarrow \text{salt} + \text{water}$$
$$\text{H}^+(aq) + \text{OH}^-(aq) \rightarrow \text{H}_2\text{O}(l)$$HCl + NaOH → NaCl + H₂O
Salt name: sodium (from NaOH) + chloride (from HCl) = sodium chloride.
Salt name: sodium (from NaOH) + chloride (from HCl) = sodium chloride.
🧂 Naming Salts
| Acid | Salt anion | Example salt |
|---|---|---|
| Hydrochloric acid (HCl) | chloride | Sodium chloride NaCl |
| Sulfuric acid (H₂SO₄) | sulfate | Magnesium sulfate MgSO₄ |
| Nitric acid (HNO₃) | nitrate | Potassium nitrate KNO₃ |
📊 pH During Neutralisation
As alkali is added to acid, pH rises from below 7 to above 7. At the equivalence point for strong acid + strong base, pH = 7.
Antacid tablets use neutralisation — they contain bases (CaCO₃, Mg(OH)₂) to neutralise excess stomach acid (HCl).
Ready to test yourself? Click the Quiz tab above to practise questions on this topic!
Interactive Demonstration — Neutralisation
Watch the pH change as base is added to acid.
⚗️ Salt Predictor
Calculate the volume of base needed to neutralise an acid (C₁V₁ = C₂V₂).