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Chemistry LibreTexts

1: The Properties of Gases

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    • 1.1: The Perfect Gas
      One way to begin to describe the nature of matter is to make a simplified, idealized model. The perfect gas is one such idealized model. In a perfect gas (or ideal gas), there are no interactions among the particles, which themselves have no volume. In this section it will be shown how a sample of idealized gas particles trapped in a container can be described by the perfect gas law, using the four variables of pressure, temperature, the number of gas particles, and the volume of the container.
    • 1.2: The Kinetic Model
      The behavior of ideal gases is explained by the kinetic molecular theory of gases. Molecular motion, which leads to collisions between molecules and the container walls, explains pressure, and the large intermolecular distances in gases explain their high compressibility. Although all gases have the same average kinetic energy at a given temperature, they do not all possess the same root mean square speed. The actual values of speed and kinetic energy are not the same for all gas particles.
    • 1.3: Real Gases (Deviations From Ideal Behavior)
      Real gas molecules have volume and experience intermolecular forces, and so are not accurately described by the perfect gas law. However, the perfect gas law can be modified to take into account the non-ideality of real gases. In this section we will describe how the characteristics of real gases cause their non-ideality, and then derive the modified gas laws.

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