Lista 2 – 2° Lei da Termodinâmica
Exercícios sugeridos do Atkins cap 3 8ed – Exercícios -3, 4, 6, 11, 13; problema 6
1 - The figure below depicts the isothermal compression of an ideal gas.
Start from the First and Second Laws of thermodynamics and calculate the molar
entropy change of the system, Ssys, for a compression that reduces the volume by
half, V2 = 1/2V1. For this problem use R = 10 J. mol-1 . K-1, ln (2) = 0,7, and ln(1/2)=-0,7.
2 - The figure below depicts the isothermal compression of an ideal gas.
If the compression is done along a reversible path, calculate the change in the entropy
of the surroundings, Ssurr, for a compression that reduces the volume by half, V2 =
1/2V1. For this problem use R = 10 J. mol-1 . K-1, ln (2) = 0,7, and ln(1/2)=-0,7.
3 - Given an ideal gas, determine qrev and S for path I e II in the V, P plane illustrated
in the Figure below.
4 - Given an ideal gas, determine qrev and S for proceeding first along path I and then
along path II in the V, P plane illustrated in the Figures for Problems 3, resulting in a
net change from P1, V1, T1  P2, V2, T1.
5 - Consider the reversible and isothermal expansion of an ideal gas from a pressure of
10 bar to a pressure of 2 bar. Defining the system as the gas and the surroundings as
everything else,
 Stotal = Ssystem + Ssurroundings
the change in the entropy of the system at 300 K is Ssystem = 13,4 J . mol-1 . K-1.
Which of the following statements is TRUE if you carry out the same isothermal
expansion, but you carry it out irreversibly against an external pressure of 0 bar?
(a) The entropy change for the system, Ssystem, will be larger than in the reversible
case.
(b) The entropy change for the surroundings,  Ssurroundings, will be 13,4 J . mol-1 . K-1.
(c) The total entropy change will be larger than in the reversible case.
(d) all of the above
Respostas: 1- -7J/mol.K; 2 – 7J/mol.K; 3 – path I: qrev 
II - qrev 

T1
T41
T2
T1
cv dT e S  
T4
T2
cv
dT ; path
T
V 
cv
dT  nR ln  2  ; 4 - qrev  nR(T1  T4 ) e
T4 T
 V1 
cv dT  nR (T1  T4 ) e S  
V 
S  nR ln  2  ; 5 - c
 V1 

T1