Avogadro's law

Principle

In 1811, Avogadro stated his hypothesis that under the same conditions of pressure and temperature, equal volumes of all gases contain equal numbers of components (molecules, atoms). He derived this from the uniformity of the behaviour of (ideal) gases on increases in temperature and pressure (see the Gas Laws) and the Law of Volumes. When Avogadro's supposition is correct, then 6 parts by volume of CO and 3 parts by volume of O₂ must form 6 parts by volume of CO₂ when pressure and temperature are the same before and after the reaction. Similarly, at a temperature a little above 100°C, a gas mixture containing 6 parts by volume of H₂ and 3 parts by volume of 0₂ must give 6 parts by volume of steam, and a mixture containing 5 parts by volume of H₂ and 5 parts by volume of Cl₂ must give 1 0 parts by volume of HCI. In the following experiments we will carry out the reactions named above to test the correctness of the hypothesis.

Benefits

• Safe and controlled test procedure by slow eudiometer
• Practical gas bar for storing the gases
• Special heater for glass jacket for optimal temperature control

Tasks

Perform the following reactions to verify Avogadro's law:

1. Preparation of carbon monoxide and chlorine
2. The carbon monoxide/oxygen reaction
3. The hydrogen/oxygen reaction at above 100°C
4. The hydrogen/chlorine reaction at above 100°C

Learning objectives

• Avogadro's law
• Gas laws
• Carbon monoxide
• Hydrogen
• Chlorine
• Oxygen

Necessary accessories

• Precision balance 620g/0.001g