Chem. 444
Instructor:
Nancy Makri
PROBLEM McQ 2014
Show that
2
2
1
1
ln
ln
V
T
V
S
C
R
T
V
∆
=
+
for a constantpressure process if
V
C
is taken from T
1
, V
1
to T
2
, V
2
assuming that
V
C
is independ
ent of temperature. Calculate the value of
S
∆
if one mole of N
2
(g) is expanded from 20.0 dm
3
at
273 K to 300 dm
3
at 400 K. Take
P
C
= 29.4 JK
1
mol
1
.
(
)
(
)
rev
V
V
q
C
T dT
C
T dT
PdV
nRdV
dS
T
T
T
T
V
δ
=
=
+
=
+
2
2
1
1
2
2
1
1
ln
ln
T
V
V
V
T
V
C dT
RdV
T
V
S
C
R
T
V
T
V
∆
=
+
=
+
∫
∫
Recall
P
V
V
P
C
C
R
C
C
R
=
+
⇒
=

So after the proper substitutions
1
1
30.6
S
JK
mol


∆
=
PROBLEM McQ 2015
In this problem, we will consider a twocompartment system like that in Figure 20.4, except that
the two subsystems have the same temperature but different pressures and the wall that separates
them is flexible rather than rigid. Show that in this case,
(
29
B
B
A
dV
dS
P
P
T
=

Interpret this result with regard to the sign of
B
dV
when
B
A
P
P
and when
B
A
P
P
<
.
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 Fall '08
 Gruebele,M
 Thermodynamics, Mole

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