Acids react in predictable ways with metals, metal oxides, metal hydroxides, and metal carbonates. These are all important reactions for making salts, and they are examples of neutralisation.

1. Acid + Metal → Salt + Hydrogen

This reaction happens with reactive metals like magnesium, zinc, and iron.

Example:
Hydrochloric acid + magnesium → magnesium chloride + hydrogen
2HCl + Mg → MgCl₂ + H₂

💡 Hydrogen gas is released – you can test it with a lit splint (squeaky pop test)

2. Acid + Metal Oxide → Salt + Water

Metal oxides are bases. This is a neutralisation reaction.

Example:
Sulfuric acid + copper(II) oxide → copper sulfate + water
H₂SO₄ + CuO → CuSO₄ + H₂O

3. Acid + Metal Hydroxide → Salt + Water

Metal hydroxides are alkalis. This is also a neutralisation reaction.

Example:
Hydrochloric acid + sodium hydroxide → sodium chloride + water
HCl + NaOH → NaCl + H₂O

4. Acid + Metal Carbonate → Salt + Water + Carbon Dioxide

This reaction produces bubbles of carbon dioxide gas, along with a salt and water.

Example:
Nitric acid + calcium carbonate → calcium nitrate + water + carbon dioxide
2HNO₃ + CaCO₃ → Ca(NO₃)₂ + H₂O + CO₂

💡 Carbon dioxide turns limewater cloudy – test for it after the reaction.

Naming the salt

The name of the salt depends on:

• The acid used
• The metal/metal compound used