9.8: Key Terms

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9.8: Key Terms

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Glossary Entries

Word(s)	Definition	Image	Caption	Link	Source
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 speed (urms)	measure of average speed for a group of particles calculated as the square root of the average squared speed
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

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