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.

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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.