Thermal Decomposition

To understand this type of reaction, we can break down the name ‘Thermal’ ‘Decomposition’

  • Thermal is a word relating to heat
  • Decomposition is a word relating to breaking things down

Therefore, in a thermal decomposition reaction, heat is applied to break down a chemical into different chemicals. A key difference about thermal decomposition is that when heated, a single reactant forms more than one product.

Many metal carbonates can take part in thermal decomposition For example, Copper carbonate decomposes to form copper oxide and carbon dioxide. In this case:

Copper carbonate ⮕ Copper oxide + Carbon dioxide

Otherwise written as

CuCO3 (s) ⮕ CuO (s) + CO2 (g)

Keep in mind, there is only one reactant (calcium carbonate)

In this reaction, copper carbonate is heated in a test tube. This will result in the release of carbon dioxide gas and copper oxide solid will remain in the test tube.

Another example is

Calcium carbonate ⮕ Calcium oxide + Carbon dioxide

Otherwise written as

CaCO3 (s) ⮕ CaO (s) + CO2 (g)

Where calcium carbonate decomposes to form calcium oxide and carbon dioxide.

In this reaction, calcium carbonate is heated in a test tube. This will result in the release of carbon dioxide gas and calcium oxide solid will remain in the test tube.

Apparatus for Decomposition Reactions

Decomposition

A decomposition reaction is a type of reaction. Note, the name doesn’t include ‘thermal’, which means the reaction doesn’t involve heat. In this chemical reaction, the chemical breaks down on its own.

An example of this type of reaction is when hydrogen peroxide breaks down to form hydrogen and oxygen. The equation is:

Hydrogen peroxide ⮕ Oxygen + Water

Or more specifically

2H2O2 ⮕ O2 + 2H2O