Reactions of metals with acids

This lesson covers: 

  1. The products formed when metals react with acids
  2. How the reactivity of the metal affects the reaction
  3. Examples of the reaction of metals with acids

Acids and metals react to form new compounds

When acids and metals react, the products formed are a salt and hydrogen gas.


General equation: Metal + Acid → Salt + Hydrogen


For example magnesium reacts with hydrochloric acid to form magnesium chloride (a salt) and hydrogen gas.

Word equation: Magnesium + Hydrochloric acid —> Magnesium chloride + hydrogen

Comparing Reactivity and Reactions

A metal's reactivity determines how it will react with acid.

Some metals are very reactive.

Illustration showing potassium reacting explosively with acid, producing a pop sound and flames.
  • Potassium, sodium, and calcium react violently with acids.
  • You will see lots of gas bubbles produced, fire or even an explosion.

Some metals are moderately reactive.

Illustration showing magnesium reacting vigorously with acid producing a pop sound and flames.
  • Magnesium, aluminium, zinc, iron, lead react fairly well with acids.
  • You will see fizzing and bubbling caused by the gas produced.

Some metals are unreactive

Illustration showing that gold does not react with acid and makes no popping sound.
  • Copper, silver, and gold are unreactive.
  • You will see no change when they are placed in acids.

Examples of the reaction of metals with acids

When metals react with acids, the products formed depend on the acid used in the reaction.


zinc + hydrochloric acid —> zinc chloride + hydrogen

Zn + 2HCl → ZnCl2​ + H2​


magnesium + sulfuric acid —> magnesium sulfate + hydrogen

Mg + H2​SO4 → MgSO4​ + H2​