Gases and the Gas Laws

Avogadro s law At constant temperature and pressure, the volume of a gas is directly proportional to the number of moles doubling the number of moles at a constant temperature and pressure doubles the volume. 

Boyle s law At constant temperature, the volume of a fixed number of moles of gas is 

These three laws are summarized in the general gas law relating volume (V), pressure (P), number of moles (n), and absolute temperature (T) expressed as follows  

This equation can be arranged in a form that can be solved for a new volume resulting from changes in P, n, or T. 

Gases require special attention because they display special and unique properties— properties different from liquids and solids. In this chapter, we examine these properties and describe a theory by which they can be explained. In addition, a number of mathematical relationships, referred to as gas laws, will be developed and used to solve problems. We will also explore the stoichiometry of chemical reactions in which gases are involved. 

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The few examples illustrated above demonstrate how gases and the gas laws affect our lives on a daily basis. We are surrounded by gas and our lives are dependent on a steady supply of gas. Humans can survive a few weeks without food, a few days without water, but only a few minutes without a steady supply of air. In this chapter, we have focused on some of the unique properties of gases and the gas laws. We continue our exploration of gases when we examine phase changes in Chapter 10 and solubility in Chapter 11. 

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