Carbonates and Greenhouse Gas

IGCSE Edexcel Chemistry
2.12-2.13 Thermal decomposition and carbon dioxide
Key Concept: Heating metal carbonates produces carbon dioxide. Carbon dioxide is a greenhouse gas.

Section A: Thermal Decomposition

1. Write the general word equation for metal carbonate decomposition. [2]
2. Write the balanced symbol equation for calcium carbonate decomposing when heated. [1]
3. Describe a test to confirm the gas produced is carbon dioxide. [2]

Section B: Greenhouse Effect

4. Explain how carbon dioxide contributes to the greenhouse effect. [3]
5. State two human activities that increase carbon dioxide levels in the atmosphere. [2]

Total marks: 10

Mark Scheme

1. Metal carbonate -> metal oxide + carbon dioxide [2]
2. CaCO3 -> CaO + CO2 [1]
3. Bubble through limewater; turns cloudy/milky [2]
4. CO2 absorbs infrared radiation; traps heat; warms atmosphere [3]
5. Burning fossil fuels; deforestation; cement manufacture [2]