Learn about neutralisation, solubility rules and the uses of salts in everyday life
Neutralisation = when an acid and a base react to form a salt + water. The resulting solution is neutral (neither acidic nor alkaline).
Common Acids and the salts they form:
| Acid | Formula | Salt formed |
|---|---|---|
| Hydrochloric acid | HCl | Chloride |
| Nitric acid | HNO₃ | Nitrate |
| Sulfuric acid | H₂SO₄ | Sulfate |
Common Alkalis:
| Alkali | Formula |
|---|---|
| Sodium hydroxide | NaOH |
| Potassium hydroxide | KOH |
| Calcium hydroxide | Ca(OH)₂ |
| Ammonium hydroxide | NH₄OH |
Stomach produces excess HCl → causes indigestion. Antacids (e.g. milk of magnesia = Mg(OH)₂) neutralise the acid.
Acid + Base → Salt + Water
Bee sting = ACIDIC → treat with baking soda (NaHCO₃) – a base.
Wasp sting = ALKALINE → treat with vinegar or lemon juice – an acid.
Soil too acidic (from excess fertilisers or acid rain) → add lime (CaO) or slaked lime (Ca(OH)₂) to neutralise. This is called "liming".
SO₂ and NO₂ from factories → absorb with calcium carbonate, calcium oxide, or calcium hydroxide (all bases) to reduce acid emissions.
Some salts dissolve in water (soluble), others don't (insoluble).
Enhances the taste of food (table salt)
Used as fertilisers to help plants grow
Used as laxatives (help digestive system)
Used in baking — makes bread/cake rise
Used in the manufacture of glass
Used in Plaster of Paris (casts for broken bones)
Test what you've learnt! Pick the best answer.