Methods of Preparation of Acids

There are several methods of preparation of acids. These include the following:

1. By the reaction between an acidic oxide of a non-metal (acid anhydride) and water.

SO₂(g) + H₂O(l) → H₂SO₃(aq) Trioxosulphate(IV)

P₄O₁₀(s) + 2H₂O(l) → 4HPO₃(aq) Trioxophosphate(V)

2. Displacement of a weaker of more volatile acid from its salt by a stronger or less volatile acid.

NaCl(s) + H₂SO₄(aq) → NaHSO₄(aq) + HCl(aq)

Na₂B₄O₇(s) (Borax) + H₂SO₄(aq) + 5H₂O(l) → Na₂SO₄(aq) + 4H₃BO₃(aq) (trioxoborate(III) acid)

3. Displacement of insoluble sulphide from a metallic salt by hydrogen sulphide.

Pb(C₂H₃O₂)₂(aq) + H₂S(g) → PbS(s) + 2CH₃COOH(aq) (Ethanoic acid)