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Gas chemistry - (CCEA)Reactions of carbon dioxide

The Earth atmosphere is a mixture of gaseous elements and compounds. We can prepare samples of common gases such as hydrogen, oxygen and carbon dioxide in the laboratory and examine their properties and reactions.

Part of Chemistry (Single Science)Further chemical reactions, rates and equilibrium, calculations and organic chemistry

Reactions of carbon dioxide

Reaction with water

Carbon dioxide reacts with water to form the weak acid, carbonic acid, H2CO3:

CO2 + H2O 鈫 H2CO3

The acid cannot be isolated from the solution and so is often simply written as CO2(aq). Carbonic acid causes the acidity in fizzy drinks.

Reaction with limewater

Carbon dioxide reacts with limewater (a solution of calcium hydroxide, Ca(OH)2), to form a white (appears milky) of calcium carbonate, CaCO3. Adding more carbon dioxide results in the precipitate dissolving to form a colourless solution of calcium hydrogencarbonate.

Ca(OH)2(aq) + CO2(g) 鈫 CaCO3(s) + H2O(l)

CaCO3(s) + CO2(g) + H2O(l) 鈫 Ca(HCO3)2(aq)

This is used as a test for carbon dioxide. When carbon dioxide is bubbled through limewater the limewater changes from colourless to milky.

Three test tubes used in carbon dioxide test
The limewater test for carbon dioxide
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