ChE 485
Mid

Term Spring 2012
Feb. 23, 2012
1.
Write your
‘
favorite
’
form for the stability matrix for a binary fluid using the
potential
. Transform
to
and now write a
nother form for the stability matrix. In both cases at a limit of
stability what are the conditions on these matrices?
(20)
2.
The compressibility
and expansivity
of a pure fluid are given by the
foll
owing definitions:
Prove the following thermodynamic i
dentity
:
If you calculate the isot
hermal entropy change for a gas
as it expands from
to
using this equation and the virial equation truncated after the
B
term, what condition
must
B
have so that this entropy change is
0?
(35)
3.
What is the condition on
B
for the virial equation
,
truncated after the
B
term
,
to
ensure a stable single phase for a pure fluid? Can this same equation of state
predict a phase transition? If not, why not?
(20)
4.
If you had to get the virial coefficients
B
and
C
for a pure fluid by comparing it to
the VDW equation of state what would b
e the correspondence between the pure
component parameters in both models. [Hint: The identity
might come in useful].
(25)
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