Deck 15: Thermodynamics

Question 1

On a $\mathrm{PV}$ diagram where pressure is in atmospheres and $\mathrm{V}$ is in liters the area is measured in liter-atmospheres. What is the number of Joules in 1.00 liter-atmosphere?

A) 101.3
B) 15.7
C) 65.2
D) 83.1
E) 22.4

Answer 1

101.3

Question 2

Using $0.0200 \mathrm{~mol}$ of an ideal monatomic gas, an isochoric process from state $\mathrm{A}(230 \mathrm{kPa}, 1.0 \mathrm{~L}$ ) to $\mathrm{B}(98$ $\mathrm{kPa}, 1.0 \mathrm{~L}$ ) results in what change in internal energy?

A) $-375 \mathrm{~J}$
B) $-200 \mathrm{~J}$
C) $+200 \mathrm{~J}$
D) $+375 \mathrm{~J}$

Answer 2

$-200 \mathrm{~J}$

Question 3

$1.00 \mathrm{~mol}$ of oxygen gas $\left(\mathrm{O}_{2}\right)$ is heated at a constant pressure of $1.00 \mathrm{~atm}$ from $10.0^{\circ} \mathrm{C}$ to $25.0^{\circ} \mathrm{C}$ . How much heat is absorbed by the gas?

A) $288 \mathrm{~J}$
B) $389 \mathrm{~J}$
C) $544 \mathrm{~J}$
D) $436 \mathrm{~J}$

Answer 3

$436 \mathrm{~J}$

Question 4

$1.00 \mathrm{~mol}$ of oxygen gas $\left(\mathrm{O}_{2}\right)$ is heated at constant pressure of $1.00 \mathrm{~atm}$ from $10.0^{\circ} \mathrm{C}$ to $25.0^{\circ} \mathrm{C}$ . What is the change of volume of the gas in this process?

A) $0.86 \mathrm{~L}$
B) $1.88 \mathrm{~L}$
C) $2.09 \mathrm{~L}$
D) $1.23 \mathrm{~L}$

Question 5

$1.00 \mathrm{~mol}$ of oxygen gas $\left(\mathrm{O}_{2}\right)$ is heated at constant pressure of $1.00 \mathrm{~atm}$ from $10.0^{\circ} \mathrm{C}$ to $25.0^{\circ} \mathrm{C}$ . What is the work done by the gas during this expansion?

A) $172 \mathrm{~J}$
B) $125 \mathrm{~J}$
C) $159 \mathrm{~J}$
D) $102 \mathrm{~J}$

Question 6

$1.00 \mathrm{~mol}$ of oxygen gas $\left(\mathrm{O}_{2}\right)$ is heated at constant pressure of $1.00 \mathrm{~atm}$ from $10.0^{\circ} \mathrm{C}$ to $25.0^{\circ} \mathrm{C}$ . From the first law, calculate the change of internal energy of the gas in this process.

A) $365 \mathrm{~J}$
B) $155 \mathrm{~J}$
C) $291 \mathrm{~J}$
D) $312 \mathrm{~J}$

Question 7

A very efficient engine has the following characteristics-combustion $=1,900^{\circ} \mathrm{C}$ , exhaust $=430^{\circ} \mathrm{C}, 5.0 \times$ $10^{6}$ cal of fuel produces $1.4 \times 10^{7} \mathrm{~J}$ of work in one hour. What is the output in $\mathrm{hp}$ ? $(1 \mathrm{hp}=745.7 \mathrm{~W})$

A) $7.3 \mathrm{hp}$
B) $5.2 \mathrm{hp}$
C) $8.1 \mathrm{hp}$
D) $6.3 \mathrm{hp}$

Question 8

A heat engine has an efficiency of $25.0 \%$ and a power output of $600 \mathrm{~W}$ . What is the rate of heat input?

A) $2.4 \mathrm{~kW}$ .
B) $1.8 \mathrm{~kW}$ .
C) $3.0 \mathrm{~kW}$ .
D) $2.0 \mathrm{~kW}$ .

Question 9

A refrigerator uses $40.0 \mathrm{~J}$ of work to extract $90.0 \mathrm{~J}$ from a heat reservoir at $0.00^{\circ} \mathrm{C}$ . What is the coefficient of performance for the refrigerator?

A) 2.05
B) 2.85
C) 2.25
D) 1.60

Question 10

$120 \mathrm{~J}$ of heat flows by thermal conduction from $100^{\circ} \mathrm{C}$ to $0.00^{\circ} \mathrm{C}$ . What is the net change in entropy for this process?

A) $0.034 \mathrm{~J} / \mathrm{K}$
B) $0.118 \mathrm{~J} / \mathrm{K}$
C) $0.338 \mathrm{~J} / \mathrm{K}$
D) $0.201 \mathrm{~J} / \mathrm{K}$

Question 11

When $1.000 \mathrm{~kg}$ of ice melts, $33.00 \times 10^{4} \mathrm{~J} / \mathrm{kg}$ of heat are needed. What is the entropy change of the ice in the melting process?

A) $1,684 \mathrm{~J} / \mathrm{K}$
B) $1,209 \mathrm{~J} / \mathrm{K}$
C) $758.0 \mathrm{~J} / \mathrm{K}$
D) $2,316 \mathrm{~J} / \mathrm{K}$

Question 12

When $2.000 \mathrm{~kg}$ of water evaporates, $22.60 \times 10^{5} \mathrm{~J} / \mathrm{kg}$ of heat are needed. What is the entropy change of the water in the boiling process?

A) $6,750 \mathrm{~J} / \mathrm{K}$
B) $12,120 \mathrm{~J} / \mathrm{K}$
C) $5,844 \mathrm{~J} / \mathrm{K}$
D) $8,566 \mathrm{~J} / \mathrm{K}$

Question 13

It can be shown that the change in entropy in heating or cooling a sample is given by the relation $\Delta \mathrm{S}=\mathrm{mc} \ln$ $\left(\mathrm{T}_{\mathrm{F}} / \mathrm{T}_{\mathrm{i}}\right)$ , where $\mathrm{m}$ is the mass of the sample, $\mathrm{c}$ is the specific heat of the sample, and $\mathrm{T}_{\mathrm{F}}$ and $\mathrm{T}_{\mathrm{i}}$ are the final and initial temperatures, respectively. What is the change in entropy when 10.0 grams of lead with a specific heat of $0.452 \mathrm{~J} / \mathrm{g} \mathrm{K}$ is heated from $10.0^{\circ} \mathrm{C}$ to $50.0^{\circ} \mathrm{C}$ ?

A) $0.90 \mathrm{~J} / \mathrm{K}$
B) $0.30 \mathrm{~J} / \mathrm{K}$
C) $0.60 \mathrm{~J} / \mathrm{K}$
D) $0.45 \mathrm{~J} / \mathrm{K}$

Question 14

It can be shown that the change in entropy in heating or cooling a sample is given by the relation $\Delta \mathrm{S}=\mathrm{mc} \ln$ $\left(\mathrm{T}_{\mathrm{F}} / \mathrm{T}_{\mathrm{i}}\right)$ , where $\mathrm{m}$ is the mass of the sample, $\mathrm{c}$ is the specific heat of the sample, and $\mathrm{T}_{\mathrm{F}}$ and $\mathrm{T}_{\mathrm{i}}$ are the final and initial temperatures, respectively. What is the change in entropy when 20.0 grams of aluminum with a specific heat of $0.900 \mathrm{~J} / \mathrm{g} \mathrm{K}$ is cooled from $60.0^{\circ} \mathrm{C}$ to $10.0^{\circ} \mathrm{C}$ ?

A) $+2.93 \mathrm{~J} / \mathrm{K}$
B) $0.00 \mathrm{~J} / \mathrm{K}$
C) $+2.50 \mathrm{~J} / \mathrm{K}$
D) $-2.93 \mathrm{~J} / \mathrm{K}$

Question 15

It can be shown that the change in entropy in heating or cooling a sample is given by the relation $\Delta \mathrm{S}=\mathrm{mc} \ln$ $\left(T_{F} / T_{i}\right)$ , where $m$ is the mass of the sample, $c$ is the specific heat of the sample, and $T_{F}$ and $T_{i}$ are the final and initial temperatures, respectively. What is the change in entropy when 20.0 grams of aluminum with a specific heat of $0.900 \mathrm{~J} / \mathrm{g} \mathrm{K}$ is heated from $10.0^{\circ} \mathrm{C}$ to $60.0^{\circ} \mathrm{C}$ ?

A) $-2.93 \mathrm{~J} / \mathrm{K}$
B) $+2.50 \mathrm{~J} / \mathrm{K}$
C) $+2.93 \mathrm{~J} / \mathrm{K}$
D) $0 \mathrm{~J} / \mathrm{K}$

Question 16

2.00 moles of an ideal gas freely expands from 1.50 liters to 4.00 liters. The change in entropy in the expansion is

A) $16.3 \mathrm{~J} / \mathrm{K}$
B) $5.80 \mathrm{~J} / \mathrm{K}$
C) $18.7 \mathrm{~J} / \mathrm{K}$
D) $8.50 \mathrm{~J} / \mathrm{K}$

Question 17

1.50 moles of an ideal gas freely expands from 1.00 liter to 4.50 liters. The change in entropy of the gas in the expansion is

A) $5.80 \mathrm{~J} / \mathrm{K}$
B) $8.50 \mathrm{~J} / \mathrm{K}$
C) $18.7 \mathrm{~J} / \mathrm{K}$
D) $16.3 \mathrm{~J} / \mathrm{K}$

Question 18

One mole of an ideal gas freely expands from 1.00 liter to 2.00 liters. The change in entropy of the gas in the expansion is

A) $5.80 \mathrm{~J} / \mathrm{K}$
B) $8.50 \mathrm{~J} / \mathrm{K}$
C) $18.7 \mathrm{~J} / \mathrm{K}$
D) $16.3 \mathrm{~J} / \mathrm{K}$

Question 19

A system in a certain macrostate has $1.2 \times 10^{3}$ microstates. Through some process, the system changes the number of microstates to $3 \times 10^{4}$ . What is the change in entropy for the process?

A) $1.1 \times 10^{-23} \mathrm{~J} / \mathrm{K}$
B) $4.4 \times 10^{-23} \mathrm{~J} / \mathrm{K}$
C) $5.6 \times 10^{-23} \mathrm{~J} / \mathrm{K}$
D) $2.1 \times 10^{-23} \mathrm{~J} / \mathrm{K}$

Question 20

On a PV diagram, what kind of process is represented by a horizontal line with an arrow left to right?

A) Isobaric compression
B) Isothermal compression
C) Adiabatic process
D) Isothermal expansion
E) Isobaric expansion
F) Isochoric process

Question 21

On a PV diagram, what kind of process is represented by a vertical line with an arrow pointing downward?

A) Isobaric compression
B) Isothermal expansion
C) Isothermal compression
D) Adiabatic process
E) Isochoric process
F) Isobaric expansion

Question 22

For a system undergoing an adiabatic process,

A) $Q=\Delta U$
B) $\mathrm{Q}=-\mathrm{W}$
C) $\mathrm{Q}=-\Delta \mathrm{U}$
D) $\mathrm{Q}=\mathrm{W}$
E) $\mathrm{Q}=0$

Question 23

For a system undergoing an isothermal process,

A) $\mathrm{Q}=-\mathrm{W}$
B) $\mathrm{Q}=-\Delta \mathrm{U}$
C) $\mathrm{Q}=\mathrm{W}$
D) $\mathrm{Q}=\Delta \mathrm{U}$
E) $\mathrm{Q}=0$

Question 24

A friend tells you that he knows of a situation in which heat is passed from one body to another body with a higher temperature. He explains that he thinks the 2nd law of thermodynamics must have been violated. Is he correct?

A) No. The cooler body can give up energy to the hotter body by radioactivity or another natural process.
B) No. If the temperature difference is small enough, heat can spontaneously flow from the cooler to the hotter body.
C) Yes. Heat cannot pass from a cooler body to a hotter body.
D) No. He forgot that if external work is done on the system this is possible.