GCSE SCIENCE CHEMISTRY HIGH SCHOOL - Test and Collection of Carbon Dioxide Gas

gcsescience.com Tests for Other Gases gcsescience.com
Test for Carbon Dioxide Gas, CO₂_(g).

Carbon dioxide

1) Has no colour or smell.

2) Will put out a lit splint.

3) Will turn moist blue litmus paper red,
and moist universal indicator paper orange.
In water it forms carbonic acid (H₂CO₃), it is a weak acid (see Carbon Cycle).

Specific test.
Carbon dioxide will turn lime water 'milky' or cloudy.

Lime water is a solution of calcium hydroxide (slaked lime).
If carbon dioxide is bubbled through it,
a solid precipitate of calcium carbonate is formed.
Calcium carbonate is chalk or limestone,
and it is this that makes the lime water cloudy.

calcium hydroxide + carbon dioxide calcium carbonate + water.
Ca(OH)_2(aq₎ + CO_2(g) CaCO₃_(s) + H₂O_(l)

Collecting Carbon Dioxide.

Carbon dioxide is more dense than air
and can be collected by downward delivery or using a gas syringe.

gcsescience.com Contents The Periodic Table Index Quizzes gcsescience.com