Carbon Dioxide from Thermal Decomposition (Edexcel IGCSE Chemistry): Revision Note

Thermal decomposition

What is thermal decomposition?

• Thermal decomposition is the term used to describe reactions where a substance breaks down due to the action of heat

• One such reaction is the thermal decomposition of metal carbonates

• Carbonates of metals from the lower half of the reactivity series tend to decompose on heating to produce the metal oxide and carbon dioxide gas:

metal carbonate → metal oxide + carbon dioxide

Thermal decomposition of copper(II) carbonate

The thermal decomposition of copper(II)carbonate produces copper(II) oxide and carbon dioxide

• The thermal decomposition of copper(II)carbonate occurs readily on heating

• Copper(II) carbonate is a green powder and slowly darkens as black copper(II) oxide is produced

• The carbon dioxide given off can be tested by passing the gas through limewater and looking for it to turn milky

• The equation for the reaction is

CuCO₃ (s) →  CuO (s)+ CO₂  (g) 

copper(II) carbonate → copper(II) oxide + carbon dioxide