Thermal Decomposition

Key Stage 3

Meaning

Thermal Decomposition is a type of chemical reaction in which a large compound is broken down into smaller molecules due to high temperatures.

About Thermal Decomposition

When materials are heated the particles inside vibrate and move more quickly, colliding with one another. For large molecules this can cause them to collide with enough force to break the molecule apart into smaller molecules. This is thermal decomposition.

Thermal Decomposition happens to certain types of compound more than others. At this stage the thermal decompositions you should know have the general equation: Metal Carbonate → Metal Oxide + Carbon Dioxide

Examples

Metal Carbonate → Metal Oxide + Carbon Dioxide

Calcium Carbonate → Calcium Oxide + Carbon Dioxide

Copper Carbonate → Copper Oxide + Carbon Dioxide

Zinc Carbonate → Zinc Oxide + Carbon Dioxide

Experiment


1. Set up the apparatus as shown in the diagram using 20g of metal carbonate in the Boiling Tube. 2. Use a Clamp Stand to hold the Boiling Tube in place. 3. Place the Test Tube underwater to fill and hold upside down over the exit of the delivery tube. 4. Heat the metal carbonate in the Boiling Tube. 5. Observe any colour change of the substance in the Boiling Tube and collect the gas to test whether it is Carbon Dioxide.