Download Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type

Irreversibility, Disorder, and Entrop
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Numerical
1. What is the entropy change when 4 kg of water at 0°C is frozen into 4 kg of ice at 0°C?
A) 4.9 kJ/K
D) 1340 kJ/K
B) an infinite change
E) −33 kJ/K
C) −4.9 kJ/K
Ans: C
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Conceptual
2. When you make ice cubes, the entropy of the water
A) decreases.
B) remains unchanged.
C) increases.
D) is unchanged as the water cools but decreases as the water freezes.
E) decreases while the water is cooling but does not change as it turns to ice.
Ans: A
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Conceptual
3. The change in the entropy of the universe due to an operating Carnot engine
A) is zero.
B) must be positive.
C) must be negative.
D) could be positive or negative.
E) is meaningless to consider, because a Carnot engine has no connection to entropy.
Ans: A
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Conceptual
4. A quantity of heat is removed from a hot reservoir at absolute temperature T and then is
added to a cold reservoir at absolute temperature T/2. The cold reservoir experiences an
entropy increase S. What is the change in the entropy of the universe?
A) S B) zero C) –S D) 2S E) S/2
Ans: E
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Numerical
5. A car of mass 2000 kg is traveling at 22.0 m/s on a day when the temperature is 20.0ºC.
The driver steps on the brakes and stops the car. By how much does the entropy of the
universe increase?
A) 1.6 kJ/K B) 24 kJ/K C) 4.8 × 105 J/K D) 0.15 kJ/K E) 3.3 kJ/K
Ans: A
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Numerical
6. A steam power plant with an efficiency of 65% of the maximum thermodynamic
efficiency operates between 250º C and 40ºC. What is the change in the entropy of the
universe when this plant does 1.0 kJ of work?
A) 16 J/K B) 1.7 J/K C) 55 J/K D) 1.7 mJ/K E) 0.85 J/K
Ans: B
Page 1
Chapter 19: The Second Law of Thermodynamics
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Numerical
7. One mole of an ideal gas undergoes a reversible isothermal expansion from a volume of
1 L to a volume of 2 L. The change in entropy of the gas in terms of the universal gas
constant R is
A) R/2 B) 2R C) R ln(2) D) R ln(½) E) None of these is correct.
Ans: C
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Conceptual
8. A thermodynamic system is taken in equilibrium steps from State I to State II. The
quantities by which the process can be characterized are
1
2
3
4
5
internal energy,
entropy,
temperature,
work, and
heat.
Of these quantities, those that are independent of path are
A) 1, 2, and 3.
D) 1, 3, and 5.
B) 2, 3, and 4.
E) 2, 3, and 5.
C) 3, 4, and 5.
Ans: A
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Numerical
9. Two moles of a gas at T = 350 K expand quasistatically and isothermally from an initial
volume of 20 L to a final volume of 60 L. The change in entropy of the gas during this
expansion is (R = 8.314 J/mol·K)
A) –17.4 J/K
Ans: B
B) 18.3 J/K
C) 20.4 J/K
D) –24.6 J/K
E) 27.8 J/K
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Numerical
10. Three moles of a gas at T = 250 K expand quasi-statically and adiabatically from an
initial volume of 30 L to a final volume of 60 L. The change in entropy of the gas during
this expansion is (R = 8.314 J/mol·K)
A) 17.3 J/K
Ans: E
B) 18.6 J/K
C) –17.4 J/K
D) 19.5 J/K
E) zero
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Numerical
11. A container has 0.2 mole of O2 gas and the gas is heated from 0°C to 100°C. What is the
change in entropy of the gas? (R = 8.314 J/mol·K)
A) 1.82 J/K B) 1.30 J/K C) 0.78 J/K D) 26.8 J/K E) zero
Ans: A
Page 2
Chapter 19: The Second Law of Thermodynamics
Section: 19–5 Topic: Irreversibility, Disorder, and Entropy Type: Numerical
12. A block of mass m = 0.2 kg slides across a rough horizontal surface with coefficient of
kinetic friction µk = 0.5. What is the change in entropy after the block has moved a
distance of 1 m? The temperature of the block and surrounding is 22°C.
A) 4.5×10 − 2 J/K B) 3.3×10 − 3 J/K C) 6.7×10 − 3 J/K D) 9.0×10 − 3 J/K E)
zero
Ans: B
Section: 19–7 Topic: Entropy Type: Conceptual
13. Entropy is related to probability. An isolated system moves toward
A) a highly ordered state of low probability and high entropy.
B) a highly ordered state of high probability and high entropy.
C) a state of low order, high probability, and high entropy.
D) a state of low order, low probability, and high entropy.
E) a state of low order, high probability, and low entropy.
Ans: C
Section: 19–7 Topic: Entropy and Probability Type: Conceptual
14. Which of the following statements is true of an isolated system consisting of 15 gas
molecules?
A) According to the second law, the entropy of the gas cannot decrease.
B) According to the second law, the entropy of the gas cannot increase.
C) According to the second law, the entropy of the gas is not likely to decrease.
D) According to the second law, the entropy of the gas is not likely to increase.
E) According to the second law, the entropy of the gas must stay the same.
Ans: C
Section: 19–7 Topic: Entropy and Probability Type: Numerical
15. A box contains 10 red and 10 white marbles. The box is then given a good shake. What
is the probability that all the 10 red marbles will be at the bottom of the box?
A) 1/1024 B) 1/2048 C) 1/512 D) 1/2 E) zero
Ans: A
Page 3