chem exam 3

4 variables that define the behavior of a gas

pressure (P), Volume (V), Temperature (T) and moles of gas (n)

[the equation that express the relationship among these variables are called gas laws]

Boyles Law

The volume of a fixed quantity of gas maintained at constant T is inversely proportional to the pressure.

V = constant x (1/P)

PV = constant

Charles Law

The volume of a fixed amount of gas maintained at constant P is directly proportional to its absolute temperature

Avogadro’s Law

equal volumes of gases at the same temperature and pressure contain equal numbers of molecules

or

the volume of a gas at constant temperature and pressure is directly proportional to the number of moles of gas

V = constant x n

V/n = constant

ideal gas equation

PV = constant; V/T = constant; V/n = constant

PV/nT = constant; PV/nT = R —→ gas constant [0.082 Latm/mol K]

PV = nRT

unit of P: atmosphere (atm)

unit of V: Liters (L)

unit of T: Kelvin (K)

unit of n: mol

Standard Temperture and Pressure [STP]

Temperature of 0°C and Pressure of 1 atm

molar volume: the volume occupied by 1 mole of ideal gas at STP [22.4}

Density of gas

d = P(molar mass)/ RT

Dalton’s Law of Partial Pressure

Total pressure of a mixture of gases equal the sum of the pressure that each would exert if it were present alone

P_t = P_A + P_B

P_t = total pressure of gaseous mixture

P_A = partial pressure of gas A

P_B = partial pressure of gas B