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Gas chemistry - (CCEA)Hydrogen

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

Hydrogen

Physical properties of hydrogen

  • colourless, odourless gas
  • in water
  • less dense than air
  • hydrogen is , H2

Preparing and collecting hydrogen gas

Precipitation of hydrogen gas

We prepare hydrogen by reacting zinc or magnesium with dilute hydrochloric acid:

Zn + 2HCl → ZnCl2 + H2

Mg + 2HCl → MgCl2 + H2

  • hydrogen is insoluble in water, so can collect it using a gas jar in a trough of water.
  • dilute hydrochloric acid reacts vigorously with magnesium and can be dangerous.

Test for hydrogen

A lit splint applied to hydrogen gas will result in a popping sound.

Hydrogen uses

  • making the fats in margarines solidify
  • weather balloons
  • an alternative to hydrocarbon fuels
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