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Solution to Homework 3
3.1 (a) True
Please see the Equation (3.15) on Page 84 in the Levine's book.
(b) True
Please see the Equation (3.15) on Page 84 in the Levine's book.
(c) True
A Carnot cycle is defined as a reversible cycle.
(d) False
Work is not a state function. It depends on the process (path).
3.7 (a) False
The entropy is a state function. So the change of state from 1 to 2 will produce the same
change in entropy when carried out both irreversibly and reversibly.
(b) True
Heat q is not a state function. It depends on the path.
(c) True
According to the definition of change in entopy
rev
q
dS
T
.
(d) True
The entropy is extensive.
(e) True
The molar entropy is intensive.
(f)
False
According to the definition of change in entopy
rev
q
dS
T
, the heat for an isothermal
process is not necessarily zero. So the ΔS may not be zero.
(g) False
This is true only when the C
v
is regarded as a constant. However, in the real cases, C
v
varies as temperature changes.
(h) False
The process should be reversible.
(i)
False
The entropy is a state function. If two states are connected by an irreversible process, we
can construct a reversible process to link the initial and final states to calculate the change in
entropy.
(j)
True
According to the definition of change in entopy
rev
q
dS
T
(k) True
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View Full Document Those formulas only deal with the change in entropy instead of the value of S.
3.20 (a) False
If the closed system releases some heat to the surroundings reversibly, ΔS can be negative.
(b) False
If the closed system releases some heat to the surroundings reversibly, ΔS can be negative.
(c) True
See Page 93 in the Levine’s book.
(d) True
If it’s a reversible process, ΔS=0; If it’s an irreversible process, the entropy of a closed
system must increase in an irreversible adiabatic process (For proof, please see Page 9395
in the book). So ΔS cannot be negative.
(e) True
An isolated system is necessarily closed. Hence the reason is the same as (d).
(f)
False
If the process is irreversible, ΔS may not be zero.
(g) True
The reason is the same as (d).
(h) False
This is true for isolated system instead of closed system. For more details, see Page 9596
in the book.
3.21 Using
rev
q
dS
T
, we have for the signs of ΔS:
(a) dq
rev
>0 so ΔS>0.
(b) dq
rev
>0 so ΔS>0.
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This note was uploaded on 02/07/2011 for the course CHEM 131 taught by Professor Lindenberg during the Spring '08 term at UCSD.
 Spring '08
 Lindenberg

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