Preparation of carbon dioxide gas

Preparing carbon dioxide gas.

Apparatus and chemicals

  • Conical flask with side arm, thistle funnel, delivery tube
  • 3 gas jars with lids (or test tubes with stoppers)
  • Basin/trough of water
  • Test-tube rack
  • Calcium carbonate small pieces 3 g
  • 50 cm3 of hydrochloric acid 1 mol/dm3
  • Wooden Splint
  • Limewater 5 cm3
  • Universal indicator solution


  1. Carefully place the calcium carbonate into the conical flask.
  2. Collect 50 cm3 of hydrochloric acid in a small beaker.
  3. Connect the delivery tube and thistle funnel to the conical flask with the delivery tube in a basin of water.
  4. Have three gas jars/test tubes filled with water also inverted in the basin of water.
  5. Carefully pour the hydrochloric acid into the thistle funnel, wait 5 s then carefully place the first water filled gas jar/test tube over the end of the delivery tube. Allow the gas jar/test tube to fill with gas (when all of the water has been displaced).
  6. Leave the gas jar/test tube inverted in the water to retain the gas.
  7. Repeat step 5 until three gas jars/test tubes of gas have been collected.
  8. Remove each gas jars/test tube from the water as required for the following tests.

Testing the gas

  1. To the first gas jar/test tube insert a lit splint – record your observations.
  2. To the second gas jar/test tube add 1 cm3 of limewater, stopper and shake – record your observations.
  3. To the third gas jar/test tube add 5 drops of universal indicator, stopper and shake – record your observations. Add a little deionised water if no change observed and shake again.