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Lesson Focus

The Number of Moles-Volume Relationship of Gases: Avogadro’s Law

Chemistry

You will experimentally determine the relationship between the number of moles of a gas and the volume the gas occupies.

Now You Know

After completing this tutorial, you will be able to complete the following:

• Explain that one mole of an ideal gas occupies 22.4 liters of space.
• Explain that Avogadro’s Law states that ideal gases containing the same number of particles or molecules will occupy equal volumes.
• Explain that under normal conditions, equal volumes of an ideal gas contain equal number of particles.
• Explain that the number of moles and the volume of an ideal gas are directly proportional.
• Explain that ideal gases with the same number of moles will occupy the same volume if their pressure, and temperature are the same regardless of their composition.

Everything You'll Have Covered

Avogadro's law expresses the relationship between the volume of a gas and the number of moles. The law applies to ideal gases, which is a hypothetical scenario. An ideal gas is one in which the size of the gas particle is relatively negligible, there are no intermolecular forces of attraction and repulsion, and all collisions between particles are elastic. While some gases come close to behaving ideally, they will deviate from ideal behavior at least slightly. As temperatures decrease, and pressures increase, the degree of deviation will generally increase.

Avogadro's law demonstrates the relationship between moles and volume of a gas. In equation form, it is expressed as . A gas in standard conditions, 1 atmosphere (atm) of pressure and 273 K, one mole will occupy 22.4 liters of space. If temperature and pressure remain constant, the number of moles is directly proportional to the volume of the gas, regardless of the gas's composition due to particles staying far apart from one another. The particle size is relatively negligible compared to the volume of the gas.

Tutorial Details

 Approximate Time 20 Minutes Pre-requisite Concepts Learners should be familiar with ideal gases, kinetic molecular theory, moles, and phases of matter. Course Chemistry Type of Tutorial Experiment Key Vocabulary atomic mass, atomic number, Avogadro