- absolute zero
- temperature at which the volume of a gas would be zero according to Charles’s law.
- Amontons’s law
- (also, Gay-Lussac’s law) pressure of a given number of moles of gas is directly proportional to its kelvin temperature when the volume is held constant
- atmosphere (atm)
- unit of pressure; 1 atm = 101,325 Pa
- Avogadro’s law
- volume of a gas at constant temperature and pressure is proportional to the number of gas molecules
- bar
- (bar or b) unit of pressure; 1 bar = 100,000 Pa
- barometer
- device used to measure atmospheric pressure
- Boyle’s law
- volume of a given number of moles of gas held at constant temperature is inversely proportional to the pressure under which it is measured
- Charles’s law
- volume of a given number of moles of gas is directly proportional to its kelvin temperature when the pressure is held constant
- compressibility factor (Z)
- ratio of the experimentally measured molar volume for a gas to its molar volume as computed from the ideal gas equation
- Dalton’s law of partial pressures
- total pressure of a mixture of ideal gases is equal to the sum of the partial pressures of the component gases.
- diffusion
- movement of an atom or molecule from a region of relatively high concentration to one of relatively low concentration (discussed in this chapter with regard to gaseous species, but applicable to species in any phase)
- effusion
- transfer of gaseous atoms or molecules from a container to a vacuum through very small openings
- Graham’s law of effusion
- rates of diffusion and effusion of gases are inversely proportional to the square roots of their molecular masses
- hydrostatic pressure
- pressure exerted by a fluid due to gravity
- ideal gas
- hypothetical gas whose physical properties are perfectly described by the gas laws
- ideal gas constant (R)
- constant derived from the ideal gas equation R = 0.08206 L atm mol–1 K–1 or 8.314 L kPa mol–1 K–1
- ideal gas law
- relation between the pressure, volume, amount, and temperature of a gas under conditions derived by combination of the simple gas laws
- kinetic molecular theory
- theory based on simple principles and assumptions that effectively explains ideal gas behavior
- manometer
- device used to measure the pressure of a gas trapped in a container
- mean free path
- average distance a molecule travels between collisions
- mole fraction (X)
- concentration unit defined as the ratio of the molar amount of a mixture component to the total number of moles of all mixture components
- partial pressure
- pressure exerted by an individual gas in a mixture
- pascal (Pa)
- SI unit of pressure; 1 Pa = 1 N/m2
- pounds per square inch (psi)
- unit of pressure common in the US
- pressure
- force exerted per unit area
- rate of diffusion
- amount of gas diffusing through a given area over a given time
- root mean square velocity (urms)
- measure of average velocity for a group of particles calculated as the square root of the average squared velocity
- standard conditions of temperature and pressure (STP)
- 273.15 K (0 °C) and 1 atm (101.325 kPa)
- standard molar volume
- volume of 1 mole of gas at STP, approximately 22.4 L for gases behaving ideally
- torr
- unit of pressure;
- van der Waals equation
- modified version of the ideal gas equation containing additional terms to account for non-ideal gas behavior
- vapor pressure of water
- pressure exerted by water vapor in equilibrium with liquid water in a closed container at a specific temperature