Acids, Bases and Salts

Acids and bases react to form salts, which are essential in daily life.

Ions in Solution

An acid releases hydrogen ions (H⁺) in water. A base accepts H⁺; an alkali is a soluble base that releases hydroxide ions (OH⁻).

Neutralisation

H⁺ + OH⁻ → H₂O. The general reaction is acid + base → salt + water. With metals, acid + metal → salt + hydrogen.

Preparing a Soluble Salt

• React an acid with an insoluble base, such as copper oxide.
• Filter off excess base.
• Evaporate the filtrate to crystallise the salt.
• Dry the crystals between filter papers.

Practice

1. Write the ionic equation for neutralisation.
2. Name the salt formed from hydrochloric acid and sodium hydroxide.
3. Describe how to obtain pure copper sulfate crystals from copper oxide and sulfuric acid.

Recap

Acids release H⁺, alkalis release OH⁻. Neutralisation forms water and a salt, and careful evaporation gives crystals.