CHEM121 CH 9 VOCAB

effusion

the process by which a gas escapes from its container through a tiny hole into a region of lower pressure

Graham’s law of effusion

the principle that the rate of effusion of a gas is inversely proportional to the square root of its molar mass

kinetic molecular theory (KMT)

a model that explains the behavior of gases on the basis of the motion of the particles that make them up

point masses

masses with essentially no volume

elastic

(referring to the collisions of gas molecules) - they result in no net transfer of energy to the walls

root-mean-square-speed (u_rms)

the square root of the average of the squared speeds of all the particles in a population of gas particles

universal gas constant

the constant R in the ideal gas equation; its value and units depend on the units used for the variables in the equation

diffusion

the spread of a substance (usually a gas or liquid) through another

mean free path

the average distance that a particle can travel through air or any gas before colliding with another particle

barometer

an instrument that measures atmospheric pressure

manometer

an instrument for measuring the pressure exerted by a gas

Boyle’s law

the principle that the volume of a fixed quantity of gas at constant temperature is inversely proportional to its pressure

Charles’s law

the principle that the volume of a fixed quantity of gas at constant pressure is directly proportional to its absolute temperature

Avogadro’s law

the principle that the volume of a gas at constant temperature and pressure is proportional to the quantity (number of moles) of the gas

Amontons’s law

(the relationship between P and T, pressure and temperature) the principle that the pressure of a fixed quantity of gas is proportional to its absolute temperature if its volume does not change

combined gas law

the principle that the ratio PV/T for a given quantity of gas is a constant

ideal gas

a gas whose behavior is predicted by the linear relations defined by the combined gas law

ideal gas equation

the principle relating the pressure, volume, number of moles, and temperature of an ideal gas, expressed by the equation PV = nRT, where R is the universal gas constant

standard temperature and pressure (STP)

0 degree C and 1 bar as defined by IUPAC, or 1 atm (pressure) in the US

partial pressure

the contribution to the total pressure made by a component in a mixture of gases

Dalton’s law of partial pressures

the principle that the total pressure of a mixture of gases is the sum of the partial pressures of all the gases in the mixture

mole fraction (x_i)