Salt - GCSE Chemistry Definition

What is a salt?

In GCSE Chemistry, a salt is a compound that forms when the hydrogen atom in an acid is replaced by a metal.

For example, replacing the H in HCl with a potassium atom in potassium hydroxide, makes the salt potassium chloride, KCl. 

HCl (aq) + KOH (aq) → KCl (aq) + H₂O (l)

Uses of salts include fertilisers, batteries, cleaning products, healthcare products and fungicides. 

How to make a salt

The following reactions make salts:

acid + metal ⟶ salt + hydrogen

acid + base ⟶ salt + water

acid + metal carbonate ⟶ salt + water + carbon dioxide

Salts can be soluble or insoluble:

• A soluble salt can be prepared by a titration, using an alkali and an acid, or a reaction between an insoluble base and an acid.

• An insoluble salt can be formed by a precipitation reaction. 

Names of salts

The name of a salt has two parts:

1. The first part is the name of the metal

   • This is from the metal, metal oxide, metal hydroxide or metal carbonate used in the reaction.

2. The second part comes from the acid

   • Hydrochloric acid always produces chloride salts which contain the chloride ion, Cl^-

   • Sulfuric acid always produces sulfate salts which contain the sulfate ion, SO₄^2–

   • Nitric acid always produces nitrate salts which contain the nitrate ion, NO₃^–

Naming salts examples