Reactions of Acids with Metals | Chemistry for Grade 10 PDF Download

Acids take part in reactions in which salts are produced. In these reactions, the hydrogen ions in the acids are replaced by metal ions.

Reactions of acids with metals

Acid + metal → salt + hydrogen

For example: 

Hydrochloric acid + magnesium → magnesium chloride + hydrogen
2HCl(aq) + Mg(s) → MgCl₂(aq) + H₂(g)

Zinc and iron also react with hydrochloric acid.
Magnesium, zinc and iron also react with sulfuric acid. The products are a salt (in this case a sulfate) and hydrogen. 

For example:

sulfuric acid + iron → iron(II) sulfate + hydrogen
H2SO4(aq) + Fe(s) → FeSO4(aq) + H2(g)

Solved Examples

The products are zinc chloride and hydrogen.

Example 2: Name the products of the reaction between zinc and sulfuric acid, and write an equation for the reaction.

The products are zinc sulfate and hydrogen.
H₂SO₄(aq) + Zn(s) → ZnSO₄(aq) + H₂(g)

Explaining the reactions of acids with metals - Higher

2H⁺(aq) + Mg(s) → Mg²⁺(aq) + H₂(g)
This ionic equation can be split into two half equations:

• Mg(s) → Mg²⁺(aq) + 2e^- (oxidation)
• 2HCl⁺(aq) + 2e^- → HCl₂(g) (reduction)

Notice that:

• magnesium atoms lose electrons - they are oxidised
• hydrogen ions gain electrons - they are reduced

Reduction and oxidation happen at the same time, so the reactions are called redox reactions.

Example 3: Use half equations to explain why the reaction of zinc with sulfuric acid is a redox reaction.

The two half equations are:

• Zn(s) → Zn²⁺(aq) + 2e^-
• 2H+(aq) + 2e^- → H₂(g)

Zinc atoms lose electrons, so they are oxidised. Hydrogen ions gain electrons, so they are reduced. Since reduction and oxidation happen at the same time, the reaction is a redox reaction.