The States of Matter I Phase Diagrams and Gases

Under certain conditions of pressure and temperature, most substances can exist in any one of the three states of matter solid, liquid, or gas. Water, for example, can be solid ice, liquid water, or water vapor (steam). The physical properties and chemical reactivity of a substance often depend on its state. In the first part of Chapter 5, we will introduce the concept of the phase diagram, which provides us with an understanding of the conditions under which a given substance is gas, liquid, or solid, and allows us to determine the changes in pressure and/or temperature needed to transform the substance from one state into another. The ranainder of Chapter 5 is devoted to a discussion of gases, whereas the properties of liquids and solids are explored in Chapter 6. 

Gases are simpler than liquids or solids in many ways. Molecular motion in gases is totally random, and the forces of attraction between gas molecules are so 

1 Pressure and Temperature Are Two Important Macroscopic Properties of Chemical Systems 282 

2 Substances and Mixtures Can Exist as Solid, Liquid, or Gas, Depending upon the External Conditions 286 

3 The Ideal-Gas Equation Describes the Behavior of All Gases in the Limit of Low Pressure 292 

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Chapter 5 The States of Matter I Phase Diagrams and Gases... 

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