Chem 444 B
Exam 1
Page 1
Chemistry 444 B
Hour Exam #1
February 25, 2009
Each problem is worth 20 pts.
1.
The RedlichKwong equation of state is given by:
(
)
1/ 2
)
RT
A
P
V
B
T
V V
B
⎛
⎞
⎛
⎞
⎜
⎟
=
−
⎜
⎟
⎜
⎟
−
⎝
⎠
+
⎝
⎠
a)
Obtain an expression for the compressibility factor,
PV
Z
RT
=
, of a gas governed
by the RedlichKwong equation in terms of molar volume, temperature and the
appropriate constants. Note A and B are positive constants.
b)
According to the RedlichKwong equation of state, under what conditions will the
observed pressure be greater than ideal pressure?
Less than?
2. Derive the average ensemble energy, the heat capacity at constant volume, and the
pressure using the partition function for one mole of an ideal monotonic gas, by taking
the appropriate derivatives (don’t just write down the expressions!).
3/2
2
[ (
,
)]
(
,
,
)
!
2
where (
,
)
N
q V
Q N V
N
m
q V
V
h
β
β
π
β
β
=
⎛
⎞
=
⎜
⎟
⎝
⎠
3. Molecular nitrogen is heated in an electric arc. The relative population of the excited
vibrational
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 Spring '08
 JamesLis
 Chemistry, Physical chemistry, Thermodynamics, pH, Chem, Redlichkwong equation, Vibrational energy

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