6. Investigate the reaction of gases

Question 1

Preparation of carbon dioxide gas - apparatus + chemicals + methods

Answer 1

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
Method

Carefully place the calcium carbonate into the conical flask.
Collect 50 cm3 of hydrochloric acid in a small beaker.
Connect the delivery tube and thistle funnel to the conical flask with the delivery tube in a basin of water.
Have three gas jars/test tubes filled with water also inverted in the basin of water.
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).
Leave the gas jar/test tube inverted in the water to retain the gas.
Repeat step 5 until three gas jars/test tubes of gas have been collected.
Remove each gas jars/test tube from the water as required for the following tests.
Testing the gas

To the first gas jar/test tube insert a lit splint – record your observations.
To the second gas jar/test tube add 1 cm3 of limewater, stopper and shake – record your observations.
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.

Question 2

Preparing hydrogen gas - apparatus + chemicals + method

Answer 2

Apparatus and chemicals

Conical flask with side arm, thistle funnel, delivery tube
3 gas jars/test tubes and 3 stoppers
Basin/trough of water
Test tube rack
Basin/trough half-filled with water, bee hive shelf especially for gas jars
Zinc approx. 2.5 g
50 cm3 of hydrochloric acid 1 mol/dm3
Wooden splint
Method

The same method is used as for carbon dioxide except zinc (or sometimes magnesium ribbon) is used in place of calcium carbonate. Collect 3 gas jars/test tubes of hydrogen gas in the same way.

Carefully place the zinc into the conical flask.
Collect 50 cm3 of hydrochloric acid in a small beaker.
Connect the delivery tube and thistle funnel to the conical flask with the delivery tube in a basin of water.
Have three gas jars/test tube filled with water also inverted in the basin of water.
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).
Leave the gas jar/test tube inverted in the water to retain the gas.
Repeat step 5 until three gas jars/test tubes of gas have been collected.
Remove each gas jar/test tube from the water as required for the following tests.
Testing the gas

To the first gas jar/test tube insert a lit splint – record your observations. You may need to repeat using a different gas jar/test tube of the gas

Question 3

Preparing oxygen gas. - apparatus + chemicals + method

Answer 3

Apparatus and chemicals

Conical flask with side arm, thistle funnel, delivery tube
2 gas jars/test tubes and 2 stoppers
Basin/trough of water
Test tube rack
Basin/trough half-filled with water, bee hive shelf (optional, but helps to stabilise test tubes)
Manganese dioxide/manganese(IV) oxide (3 g)
Hydrogen peroxide solution (20 vol)
Wooden Splint
Method
Carefully place the manganese(IV) oxide into the conical flask.
Collect 50 cm3 of hydrogen peroxide solution in a small beaker.
Connect the delivery tube and thistle funnel to the conical flask with the delivery tube in a basin of water.
Have three test tube filled with water also inverted in the basin of water.
Carefully pour the hydrogen peroxide solution into the thistle funnel, wait 5 s then carefully place the first water filled test-tube over the end of the delivery tube. Allow the test-tube to fill with gas (when all of the water has been displaced).
Leave the test-tube inverted in the water to retain the gas.
Repeat step 5 until two test tubes of gas have been collected.
Remove each test tube from the water as required for the following tests.
Testing the gas

To the first test-tube insert a glowing splint – record your observations. Repeat with the second test-tube of gas.