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GAS LAWS IN A NUTSHELL
LAW
Density
equation
EQUATION
DESCRIPTION
d = m
V
density is mass divided by volume, units include,
g/ml or g/cm3, g/L or g/dm3
Usually pressure is expressed in atmospheres
1 atm = 760. mmHg
= 101.325kPa or 101, 325 Pa
= 29.92 inches Hg
= 760. torr
Pressure
Equation
P = force
area
Kinetic
Energy
Equation
K.E. = 1 mv2
2
measured with a thermometer
temperature is a measure of the average kinetic
energy of the molecules
Graham’s
Law of
Diffusion
rateA = √MMB
rateB
√MMA
Lighter gases diffuse faster than heavier gases. It
is not necessary to know individual rates just
relative rates
Dalton’s Law
of Partial
Pressures
Molar Mass
Conversion
Ptot = p1 + p2 + ..
ntot = n1 + n2 + ..
no. of moles = mass in g
Always round atomic mass to a tenth while
molar mass g/mol calculating
Charles’ Law
V = constant
T
Boyle’s Law
PV = constant
Combined
Gas Equation
P1V1= P2V2
T1
T2
Avogadro’s
Law
Molar
Volume
Ideal Gas Law
Pwet = pwater vapor + pdry gas
partial pressure = mole fraction * Ptot
V = constant
n
1 mole of any gas has the
same volume at STP
conditions
PV =nRT
V1 = V2 at constant P and n
T1
T2 remember that all temp. are in K
P1V1 = P2V2 at constant T and n
remember that all temperatures are in Kelvin
V1 = V2 at constant temp and pressure conditions
n1 n2
Molar volume at STP = 22.4 L
R = universal gas constant = 0.0821 L.atm
mol.K
n can be calculated using a stoichiometric relation
as well