Gas Laws Cheat Sheet
STP is 1 atm and 0C
1 atm = 760 mmHg or 760 torr
1 atm = 101.3 kPa
Boyle’s Law V1P1 = V2P2
Charles’s Law
V1 = V2
T1
T2
Gay-Lussac’s Law
P1 = P2
T1 T2
Moles and Volume Law
Combined Gas Law
Ideal Gas Law
K = 273 + C (Change ALL temperatures to Kelvin!!!!)
1000 mL=1 L
Molar Volume of a Gas at STP 22.4 L/mol
V1 = initial volume
V2 = final volume
P1 = initial pressure
P2 = final pressure
T1 = initial temperature (in Kelvin)
T2 = final temperature (in Kelvin)
n1= initial moles
n2 = final moles
V1 = V2
n1
n2
V1P1 = V2P2
n1T1
n2T2
PV = nRT
P = pressure in atm, kPa, or mmHg (Make sure you pick correct R!)
V = volume in liters
n = number of moles
T = temperature in Kelvin
Ideal Gas Constant = R = 0.0821 L • atm
= 8.31 L • kPa
= 62.4 L • mmHg
mol • K
mol • K
mol • K
(Pressure)(volume) = (moles)(ideal gas constant)(temperature)
Daltons Law PT = P1 + P2 + P3 + …….
PT = total pressure
P# = the partial pressures of the individual gases
Total Pressure of a Gas = (Sum of the partial pressures of the component gases)
Daltons Law applied to Gases Collected by Water Displacement
Patm or PT = Pgas + PH2O
Patm or PT = barometric pressure or total pressure
Pgas = pressure of the gas collected
PH2O = vapor pressure of water at specific temperature (table below
also on page 899 in textbook)
Water – Vapor Pressure
Temperature Pressure
Temperature Pressure
Temperature Pressure
Temperature Pressure
(ºC)
(mmHg)
(ºC)
(mmHg)
(ºC)
(mmHg)
(ºC)
(mmHg)
0.0
4.6
21.0
18.6
27.0
26.7
50.0
92.5
5.0
6.5
22.0
19.8
28.0
28.3
60.0
149.4
10.0
9.2
23.0
21.1
29.0
30.0
70.0
233.7
15.0
12.8
24.0
22.4
30.0
31.8
80.0
355.1
18.0
15.5
25.0
23.8
35.0
42.2
90.0
525.8
20.0
17.5
26.0
25.2
40.0
55.3
100.0
760.0
Graham’s Law
Rate of diffusion/effusion of A = √(MB / MA)
Rate of diffusion/effusion of B
M = molar mass of that compound
Gas A is the lighter, faster gas
Rate of diffusion/effusion is the same as the velocity
(or speed) of the gas.
After the rates of diffusion/effusion for two gases are determined, the gas with the lower molar mass will
be the one diffusing/effusing faster.