Chemistry - Ch 10 Flashcards
Vapors
substances that are liquids or solids under ordinary conditions that can also exist in the gaseous state
Pressure
conveys the idea of a force, a push that tends to move something in a given direction; = force/area
pascal (Pa)
SI unit of pressure (N/m^2)
bar
10^5 Pa; related unit of pressure (to pascal)
Standard atmospheric pressure
typical pressure at sea level; pressure sufficient to support a column of mercury 760 mm high; in SI units, this pressure equals 1.01325 x 10^5 Pa
atmosphere (atm)
non-SI unit used to express gas pressures
torr
non-SI unit AKA mm Hg; named after Evangelista Torricelli (Galileo’s student) who did mercury/atmosphere pressure experiment
Boyle’s law
the volume of a fixed quantity of gas maintained at constant temperature is inversely proportional to the pressure (V= constant x 1/p or PV = constant)
Charles’s Law
the volume of a fixed amount of gas maintained at constant pressure is directly proportional to its absolute temperature
Law of combining volumes
at a given pressure and temperature, the volume of gases that react with one another are in the ratios of small whole numbers; observed by Louis Gay-Lussac in 1808
Avogadro’s hypothesis
equal volumes of gases at the same temperature and pressure contain equal numbers of molecules
Avogadro’s law
the volume of a gas maintained at constant temperature and pressure is directly proportional to the number of moles of the gas (V = constant x n)
Ideal-gas equation
PV = nRT
ideal gas
hypothetical gas whose pressure, volume, and temperature behavior are described completely by the ideal-gas equation
Gas constant
R in the ideal gas equation
Standard temperature and pressure (STP)
conditions of 0 degrees Celsius & 1 atm; volume occupied by 1 mole of ideal gas at STP, 22.41 L is known as the molar volume of an ideal gas at STP
Dalton’s law of partial pressures
the total pressure of a mixture of gases equals the sum of the pressures that each would exert if it were present alone
partial pressure
pressure exerted by a particular component of a mixture of gases
mole fraction
X; a dimensionless number that expresses the ratio of the number of moles of one component to the total number of moles in the mixture
Kinetic-molecular theory
Rudolf Clasius’ theory of moving molecules (5 parts)
root-mean-square (rms) speed
u; speed of a molecule possessing average kinetic energy
effusion
escape of gas molecules through a tiny hole into an evacuated space
diffusion
spread of one substance throughout a space or throughout a 2nd substance
Graham’s law
law stating that the rate of effusion of a gas is inversely proportional to the square root of its molecular weight
Mean free path
the average distance traveled by a molecule between collisions; varies with pressure
van der Waals equation
an equation of state for nonideal gases that is based on adding corrections to the ideal-gas equation; the correction terms account for intermolecular forces of attraction and for the volumes occupied by the gas molecules themselves
