# 1: Gases

• 1.1: Kinetic Molecular Theory - A Model for Gases
The physical behavior of gases is explained by the kinetic theory of gases. An ideal gas adheres exactly to the kinetic theory of gases.
• 1.2: Pressure
Pressure is a force exerted over an area. Pressure has several common units that can be converted.
• 1.3: Gases - Pressure and Volume
A simple gas law relates a gas’s pressure and volume at constant temperature and amount.
• 1.4: Gases - Volume and Temperature
A simple gas law relates a gas’s volume and temperature at constant pressure and amount. In gas laws, temperatures must always be expressed in kelvins.
• 1.5: The Combined Gas Law
There are other gas laws that relate any two physical properties of a gas. The combined gas law relates pressure, volume, and temperature of a gas.
• 1.6: The Ideal Gas Law and Gas Stoichiometry
The ideal gas law relates the four independent physical properties of a gas at any time. The ideal gas law can be used in stoichiometry problems whose chemical reactions involve gases. Standard temperature and pressure (STP) are a useful set of benchmark conditions to compare other properties of gases. At STP, gases have a volume of 22.4 L per mole. The ideal gas law can be used to determine densities of gases.
• 1.7: Partial Pressures
The pressure exerted by each gas in a gas mixture is independent of the pressure exerted by all other gases present. Consequently, the total pressure exerted by a mixture of gases is the sum of the partial pressures of the components (Dalton’s law of partial pressures). The amount of gas in a mixture may be described by its partial pressure or its mole fraction. In a mixture, the partial pressure of each gas is the product of the total pressure and the mole fraction.