Quiz tests your comprehension and abbility to apply the following topics to
Common gas properties
Gas is a state of matter. In this state, all substances behave alike.
The properties of gaseous state are:
Amount of gas in moles, n, number of molecules, mass, and volume.
The pressure, P, exerted to the walls of the container by gas molecules
or by the wall to contain the gas to a fixed volume V.
The temperature, T, which is a measure of the kinetic energy of
The volume, V, occupied by a gas at temperature T, under the
The average kinetic energy of a gas, and the root mean square speed of
These properties are often expressed in various units, and ability to
convert units from one to another is always required.
Gas laws - some key equations
You are expected to have mastered the
ABCD laws of gases.
You should use the proper units for pressure, P, volume V,
and temperature T. Letters i and f following these
quantities refer to the initial and final states respectively.
A summary of key equations is given below, but you should be able to
derive one from each other, and understand the system from which these
Pi Vi = k (k is a constant)
Pi Vi = Pf Vf
T = 273.15 + tC
-- = -- = k
-- = -- = k
The ideal gas law
P V = n R T
R = (1 atm 22.4 L)/(1 mol 273.15 K)
= 0.082058 L atm / (mol K)
= 8.3145 J / (mol K)
Avogadros law and gas density
n = P V / R T
P M = --- R T -- where M is the molecular weight of the gas
P V = n R T -- Ideal gas equation
P = d R T / M -- where d is the density of the gas
d = P M / R T -- density of gas is given by this equation
M = d R T / P -- hence, the Molecular Weight of a gas is given by this.
Dalton's law of partial pressures
If Ptotal is the total pressure of a gas mixture,
Pa , Pb , Pc , ... are
partial pressures of gas A, B, C, ..., then
Ptotal = Pa + Pb + Pc + ...
If ntotal is the total number of mole, and
na , nb , nc , ... are
number of moles of gas A, B, C, ..., then
ntotal = na + nb + nc ...
nt R T = P V
= (na + nb + nc + ...) R T
= Pa + Pb + Pc + ...
The mole fraction of a gas A, xa in a system
containing ntotal mole of gas is
xa = na / ntotal
Non ideal behavior of gas
The ideal gas law has a limited precision for predicting the properties
of gases. The imprecision is known as the non-ideal behavior of gas, and the
van der Waals equation
(P + n2a / V2) (V - n b) = n R T,
has been introduced to deal with non-ideal behavior of gases, in