GCSE Chemistry · key term

Carbon dioxide

Definition

A gas made of carbon and oxygen atoms, with the formula CO₂; it was present in a large amount in the early atmosphere.

Used by Edexcel

Specification 3.12, 8.19, 8.21 · Paper 1, Paper 2

A colourless gas that turns limewater milky or cloudy.
This connects with reactions of acids: an acid reacting with a suitable metal can produce hydrogen, while an acid reacting with a metal carbonate can produce carbon dioxide. The gas test supplies evidence about which gas was actually formed.
Revise: Tests for Gases
Revise: Composition of Early Atmosphere
A gas made of carbon and oxygen, with the formula $CO_2$ . It was present in a large amount in the Earth's early atmosphere.
Revise: Decrease of Carbon Dioxide

1
For carbon dioxide, say that the gas is bubbled through limewater and that the limewater turns milky or cloudy; do not merely say that the gas is added to it.
2
Do not confuse the early atmosphere with today’s atmosphere, which contains much more oxygen and only a small proportion of carbon dioxide.
3
Build the explanation as a sequence: Earth cooled → oceans formed → atmospheric carbon dioxide dissolved in the ocean water → the amount remaining in the atmosphere decreased.

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GCSE Chemistry · key term

A gas made of carbon and oxygen atoms, with the formula CO₂; it was present in a large amount in the early atmosphere.

Used by Edexcel

Specification 3.12, 8.19, 8.21 · Paper 1, Paper 2

A colourless gas that turns limewater milky or cloudy.
This connects with reactions of acids: an acid reacting with a suitable metal can produce hydrogen, while an acid reacting with a metal carbonate can produce carbon dioxide. The gas test supplies evidence about which gas was actually formed.
Revise: Tests for Gases
Revise: Composition of Early Atmosphere
A gas made of carbon and oxygen, with the formula $CO_2$ . It was present in a large amount in the Earth's early atmosphere.
Revise: Decrease of Carbon Dioxide

1
For carbon dioxide, say that the gas is bubbled through limewater and that the limewater turns milky or cloudy; do not merely say that the gas is added to it.
2
Do not confuse the early atmosphere with today’s atmosphere, which contains much more oxygen and only a small proportion of carbon dioxide.
3
Build the explanation as a sequence: Earth cooled → oceans formed → atmospheric carbon dioxide dissolved in the ocean water → the amount remaining in the atmosphere decreased.

Create a free account to read GCSE Chemistry revision notes for your exam board and track your progress.