Making hydrogen gas

Preparing hydrogen gas

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.

  1. Carefully place the zinc 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 tube 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 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