Chapter 8: The Gas Phase Flashcards
Pressure units
1 atm = 760 mmHg = 760 torr = 101.325Kpa
Ideal Gas Law
PV = n R T
P = pressure
V = volume
n = moles
R = ideal gas constant (8.21 x 10^-2 L. atm / mol . K)
Convert K to C or vice versa
T = (temp in C) + 273 = (temp in K)
Density
ρ = m / V
m = mass
V = volume
Ideal gas AND density
m/v = PM / RT
M = molar mass
Combined Gas Law
P1 V1 / T1 = P2 V2 / T2
Combined Gas Law Rearranged
V2 = V1 [P1/P2][T2/T1]
Molar Mass
M = (ρstp) (22.4 L /mol)
product of gas’s density at STP times the STP volume of one molar of gas 22.4 L/mol
Avogadro’s Principle
n/V = k
n1/ V1=n2/ V2
Boyle’s Law
PV = k
P1V1 = P2V2
n and T are constant, pressure and volume are inversely related
Charles’s law
V/T= k
V1/T1= V2/T2
n and P are constant, temperature and volume are directly proportional
Gay-Lussac’s law
P/T = k
P1/T1= P2/T2
n and V are constant, temparature and pressure are directly proportional
Dalton’s law of partial pressure
Pt= Pa + Pb + Pc + …..
Pt = total pressure
Pa = partial pressure of gas A
Partial Pressure
Pa = Xa Pt
Pt = total pressure
Pa = partial pressure of gas A
Xa = mole fraction
Mole Fraction
Xa = moles of gas A / total moles of gas
Henry’s law
[A] = kh x Pa
[A]1 /P1 = [A]2 / P2
[A] = concentration of A in solution
kh = henry’s constant
Pa = partial pressure pf A
Average Molecular Speeds
KE = 1/2 mv^2 = 3/2 kb T
kb = boltzman constant (1.38 x 10^23 J/K)
Root-mean- square speed (urms)
urms = √’3RT/M
R = ideal gas constant
T = temperature
M = molar mass
Graham’s law
r1/r2 = √’M2/M1
r1 and r2 are the diffusion rates of gas 1 and 2
M1 and M2 are the molar masses of gas 1 and 2
van der Waals Equation of state
(P + n^2 a / V^2) (V - n b ) = n R T
P = pressure
R = universal gas constant
T = absolute temperature
V = molar volume
b = gas constant b, term for big particles
{a} = gas constant a, term for the attractive forces
V = molar volume
n = moles
