Carbon Dioxide
Chemistry: Edexcel IGCSE, topic 9.1.5
Formation of Carbon Dioxide
When heated, carbonates can thermally decompose to produce carbon dioxide gas.
Copper(II) carbonate
- An example of a carbonate that decomposes easily is copper(II) carbonate.
- As it is heated, copper(II) carbonate breaks down into copper oxide and carbon dioxide. The equation for this reaction is:
- Copper carbonate → copper oxide + carbon dioxide
- CuCO3 → CuO + CO2
Positive result
- Copper carbonate is green and copper oxide is black.
- You can see a colour change from green to black during the reaction.
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Testing for carbon dioxide
- Take an aqueous solution of limewater (calcium hydroxide) and bubble through the gas.
- If the gas is carbon dioxide, the limewater solution will turn from clear to cloudy.
Test yourself on Carbon Dioxide
A student bubbles a gas through limewater and the solution stays clear. What does this show about the gas?
What is another name for an aqueous solution of calcium hydroxide?
What is involved in a positive test for carbon dioxide?
Which gas does this experiment test for?