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Unformatted text preview: Chapter 5: The Gas Phase CH1010-1040 homepage Section 5-1: Macroscopic Properties of Gases Section 5-2: The Ideal Gas Law Section 5-3: Kinetic Molecular Theory Section 5-4: The Historical Role of Gas Phase Chemical Reactions Section 5-5: Gas Production via Double Displacement Reactions Applications Major Concept Area: Electrical Forces and Bonding Specific Concepts in this Chapter: In the gas phase, molecules are far apart. The behavior of all gases is described by a simple equation called the ideal gas law, PV = nRT. The kinetic energies of gas molecules are distributed according to the Maxwell-Boltzmann equation. The average kinetic energy of a gas molecule, KE molecule , is 3kT/2, where T is the absolute temperature and k is a constant of nature. In this chapter we begin an examination of the phases (physical states) in which a pure substance may exist. For most substances there are three phases -- solid (s), liquid (l), and gas (g). The gas phase is the simplest of the three to deal with theoretically, primarily because the molecules behave completely chaotically and therefore give rise to simply-formulated average properties. The solid phase is also relatively easily dealt with, because it is so highly organized. The liquid phase, intermediate in its degree of order, is the most difficult to model. This chapter deals with the gas phase. A subsequent chapter deals with the solid and liquid phases. We follow the chapter on the liquid phase with chapters on the energetics of conversions among phases, and equilibria between two or more phases. Of interest throughout will be the question, "Why do some substances exist as solids, some as liquids, and still others as gases at room temperature and subjected to 1 atmosphere of pressure?" Gases and their properties play an ubiquitous and critical role in our daily lives. Life is supported by the oxygen of the air, which reacts with glucose in biochemical combustion. Living systems have evolved complex molecular architecture to absorb oxygen from the air; carry it to the cells; deliver it to the cells; transport it within the cell; and supervise its multistep, controlled reaction with glucose. It is the rapid expansion of gases produced in the explosive combustion of gasoline that performs the work of the internal combustion engine. Expansion and contraction of gases in response to temperature and pressure changes is at the basis of continually changing weather patterns. Clearly an understanding of the properties, behavior, and chemical reactivity of gases is an important foundation for developing an appreciation of complex biological and technological systems. These properties, behaviors, and reactivities are the focus of this chapter....
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