Chapter 5 Flashcards
atmosphere
the mixture of gases that extends from a planet’s surface and eventually merges with outer space; the gaseous region of Earth’s crust
Avogadro’s law
the gas law stating that, at fixed temperature and pressure, equal volumes of any ideal gas contain equal numbers of particles, and, therefore, the volume of a gas is directly proportional to its amount (mol): V ∝ n
barometer
a device used to measure atmospheric pressure. most commonly, a tube open at one end, which is filled with mercury and inverted into a dish of mercury
Boyle’s law
the gas law stating that, at constant temperature and amount of gas, the volume occupied by a gas is inversely proportional to the applied (external) pressure: V ∝ 1/P
Charles’ law
the gas law stating that, at constant pressure, the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature: V ∝ T
collision frequency
the average number of collisions per second that a particle undergoes
Dalton’s law of partial pressures
a gas law stating that, in a mixture of unreacting gases, the total pressure is the sum of the partial pressures of the individual gases: Ptotal = P1 + P2 + P3 + ….
diffusion
the movement of one fluid through another
effusion
the process by which a gas escapes from its container through a tiny hole into an evacuated space
Graham’s law of effusion
a gas law stating that the rate of effusion of a gas is inversely proportional to the square root of its density (or molar mass): rate = 1/sqrt MM
ideal gas
a hypothetical gas that exhibits linear relationships among volume, pressure, temperature, and amount (mol) at all conditions; approximated by simple gases at ordinary conditions
ideal gas law
an equation that expresses the relationships among volume, pressure, temperature, and amount (mol) of an ideal gas: PV = nRT
kinetic molecular theory
the model that explains macroscopic gas behavior in terms of particles in random motion whose volumes and interactions are negligible
manometer
a device used to measure the pressure of a gas in a laboratory experimen
mean free path
the average distance a particle travels between collisions at a given temperature and pressure
millimeter of mercury mmHg
a unit of pressure based on the difference in the heights of mercury in a barometer or manometer. renamed the torr in honor of Torricelli
mole fraction (X)
a concentration term expressed as the ratio of number of moles of solute to the total number of moles (solute plus solvent)
partial pressure
the portion of the total pressure contributed by a gas in a mixture of gases
pascal (Pa)
the SI unit of pressure; 1 Pa = 1 N/m2
pressure (P)
the force exerted per unit of surface area
rms speed
the speed of a molecule having the average kinetic energy; very close to the most probable speed
standard atmosphere (atm)
the average atmospheric pressure measured at sea level and 0°C, defined as 1.01325 × 105 Pa
standard molar volume
the volume of 1 mol of an ideal gas at standard temperature and pressure: 22.4141 L
standard temperature and pressure (STP)
the reference conditions for a gas: 0°C (273.15 K) and 1 atm (760 torr)
