Examples of chemical reactions

This lesson covers: 

  1. Combustion reactions
  2. Oxidation reactions
  3. Thermal decomposition

Combustion reactions

Image showing a candle burning and fireworks exploding, illustrating combustion reactions.

Combustion is basically burning. It happens when a fuel source reacts very rapidly with oxygen, giving off heat and light energy.

For example, a candle wax fuel burning, or a firework exploding.


The combustion reaction requires:

  1. Fuel (like oil, wood, gas)
  2. Heat to get it started
  3. Oxygen (usually from air)
Word equation: methane + oxygen → carbon dioxide + water
Symbol equation: CH4​ + O2​→ CO2​ + H2​O

When a fuel like methane burns in oxygen it makes carbon dioxide and water.

The energy released can provide useful heating and lighting.

Oxidation Reactions

Oxidation means a chemical reaction where a substance chemically combines with oxygen.

So combustion reactions are classed as oxidation since the fuel reacts with oxygen.

Word equation: iron + oxygen → iron oxide
Symbol equation: Fe + O2​→ Fe2​O3​

Another example of an oxidation reaction is iron rusting.

Here the iron metal reacts with oxygen gas in the air to form iron oxide (which is the chemical name for rust)

Thermal Decomposition

Some chemical substances actually break apart into other substances when you heat them up.

This is called thermal decomposition.

Diagram showing thermal decomposition of copper carbonate into copper oxide and carbon dioxide.

For example, a green compound called copper carbonate breaks down when heated into carbon dioxide gas and black copper oxide powder.