Chemistry Structure and Properties

Nivaldo J. Tro

Chapter 12

Liquids, Solids, and Intermolecular Forces - all with Video Answers

Educators

ML

MS

Chapter Questions

Problem 1

Why do ethanol and dimethyl ether have such different properties
even though they have the same chemical formula?

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 2

Why are intermolecular forces important?

RD

Ryan Daly

Numerade Educator

Problem 3

What are the key properties of liquids (in contrast to gases and
solids)?

Ahmed Ali

Numerade Educator

Problem 4

What are the key properties of solids (in contrast to liquids and
gases)?

RD

Ryan Daly

Numerade Educator

Problem 5

What is the fundamental difference between an amorphous solid and
a crystalline solid?

Ahmed Ali

Numerade Educator

Problem 6

Which factors cause transitions between the solid and liquid state?
The liquid and gas state?

RD

Ryan Daly

Numerade Educator

Problem 7

Describe the relationship between the state of a substance, its temperature, and the strength of its intermolecular forces.

Ahmed Ali

Numerade Educator

Problem 8

From which kinds of interactions do intermolecular forces originate?

RD

Ryan Daly

Numerade Educator

Problem 9

Why are intermolecular forces generally much weaker than bonding
forces?

Ahmed Ali

Numerade Educator

Problem 10

What is the dispersion force? What does the magnitude of the dispersion force depend on? How can we predict the magnitude of the dispersion force for closely related elements or compounds?

RD

Ryan Daly

Numerade Educator

Problem 11

What is the dipole-dipole force? How can we predict the presence of
dipole-dipole forces in a compound?

Ahmed Ali

Numerade Educator

Problem 12

How is the miscibility of two liquids related to their polarity?

Nicholas White

Numerade Educator

Problem 13

What is hydrogen bonding? How can we predict the presence of hydrogen bonding in a compound?

Ahmed Ali

Numerade Educator

Problem 14

What is the ion-dipole force? Why is it important?

RD

Ryan Daly

Numerade Educator

Problem 15

What is surface tension? How does surface tension result from intermolecular forces? How is it related to the strength of intermolecular
forces?

Ahmed Ali

Numerade Educator

Problem 16

What is viscosity? How does viscosity depend on intermolecular
forces? What other factors affect viscosity?

RD

Ryan Daly

Numerade Educator

Problem 17

What is capillary action? How does it depend on the relative strengths
of adhesive and cohesive forces?

Ahmed Ali

Numerade Educator

Problem 18

Explain what happens during the processes of vaporization and condensation. Why does the rate of vaporization increase with increasing
temperature and surface area?

RD

Ryan Daly

Numerade Educator

Problem 19

Why is vaporization endothermic? Why is condensation exothermic?

Ahmed Ali

Numerade Educator

Problem 20

How is the volatility of a substance related to the intermolecular forces
present within the substance?

Ahmed Ali

Numerade Educator

Problem 21

What is the heat of vaporization for a liquid, and why is it useful?

Ahmed Ali

Numerade Educator

Problem 22

Explain the process of dynamic equilibrium. How is dynamic equilibrium related to vapor pressure?

Ahmed Ali

Numerade Educator

Problem 23

What happens to a system in dynamic equilibrium when it is disturbed in some way?

Ahmed Ali

Numerade Educator

Problem 24

How is vapor pressure related to temperature? What happens to the vapor
pressure of a substance when the temperature is increased? Decreased?

Ahmed Ali

Numerade Educator

Problem 25

Define the terms boiling point and normal boiling point.

Ahmed Ali

Numerade Educator

Problem 26

What is the Clausius-Clapeyron equation, and why is it important?

Ahmed Ali

Numerade Educator

Problem 27

Explain what happens to a substance when it is heated in a closed container to its critical temperature.

Ahmed Ali

Numerade Educator

Problem 28

What is sublimation? Cite a common example of sublimation.

Nicholas White

Numerade Educator

Problem 29

What is fusion? Is fusion exothermic or endothermic? Why?

Vasu Makani

Numerade Educator

Problem 30

What is the heat of fusion, and why is it important?

Ahmed Ali

Numerade Educator

Problem 31

Examine the heating curve for water in Section 12.7 (Figure 12.33$) .$
Explain why the curve has two segments in which heat is added to the
water but the temperature does not rise.

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 32

Examine the heating curve for water in Section 12.7 (Figure 12.33$) .$
Explain the significance of the slopes of each of the three rising segments. Why are the slopes different?

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 33

Determine the kinds of intermolecular forces that are present in each element or compound.
a. $\mathrm{N}_{2}$
b. $\mathrm{NH}_{3}$
c. $\mathrm{CO}$
d. $\mathrm{CCl}_{4}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 34

Determine the kinds of intermolecular forces that are present in each element or compound.
a. Kr
b. $\mathrm{NCl}_{3}$
c. $\mathrm{SiH}_{4}$
d. $\mathrm{HF}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 35

Determine the kinds of intermolecular forces that are present in each element or compound.
a. HCl
b. $\mathrm{H}_{2} \mathrm{O}$
c. $\mathrm{Br}_{2}$
d. $\mathrm{He}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 36

Determine the kinds of intermolecular forces that are present in each element or compound.
a. $\mathrm{PH}_{3}$
b. $\mathrm{HBr}$
c. $\mathrm{CH}_{3} \mathrm{OH}$
d. $\mathrm{I}_{2}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 37

Arrange these compounds in order of increasing boiling point. Explain your reasoning.
a. $\mathrm{CH}_{4}$
b. $\mathrm{CH}_{3} \mathrm{CH}_{3}$
c. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl}$
d. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 38

Arrange these compounds in order of increasing boiling point. Explain your reasoning.
a. $\mathrm{H}_{2} \mathrm{S}$
b. $\mathrm{H}_{2} \mathrm{Se}$
c. $\mathrm{H}_{2} \mathrm{O}$

Ahmed Ali

Numerade Educator

Problem 39

Pick the compound with the highest boiling point in each pair. Explair your reasoning.
a. $\mathrm{CH}_{3} \mathrm{OH}$ or $\mathrm{CH}_{3} \mathrm{SH}$
b. $\mathrm{CH}_{3} \mathrm{OCH}_{3}$ or $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$
c. $\mathrm{CH}_{4}$ or $\mathrm{CH}_{3} \mathrm{CH}_{3}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 40

Pick the compound with the highest boiling point in each pair. Explain your reasoning.
a. $\mathrm{NH}_{3}$ or $\mathrm{CH}_{4}$
b. $\mathrm{CS}_{2}$ or $\mathrm{CO}_{2}$
c. $\mathrm{CO}_{2}$ or $\mathrm{NO}_{2}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 41

In each pair of compounds, pick the one with the higher vapor pressure at a given temperature. Explain your reasoning.
a. $\mathrm{Br}_{2}$ or $\mathrm{I}_{2}$
b. $\mathrm{H}_{2} \mathrm{S}$ or $\mathrm{H}_{2} \mathrm{O}$
c. $\mathrm{NH}_{3}$ or $\mathrm{PH}_{3}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 42

In each pair of compounds, pick the one with the higher vapor pressure at a given temperature. Explain your reasoning.
a. $\mathrm{CH}_{4}$ or $\mathrm{CH}_{3} \mathrm{Cl}$
b. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$ or $\mathrm{CH}_{3} \mathrm{OH}$
c. $\mathrm{CH}_{3} \mathrm{OH}_{\text { or } \mathrm{H}_{2} \mathrm{CO}}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 43

Determine if each pair of compounds forms a homogeneous solution when combined. For those that form homogeneous solutions, indicate the type of forces that are involved.
a. $\mathrm{CCl}_{4}$ and $\mathrm{H}_{2} \mathrm{O}$
b. $\mathrm{KCl}$ and $\mathrm{H}_{2} \mathrm{O}$
c. $\mathrm{Br}_{2}$ and $\mathrm{CCl}_{4}$
d. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$ and $\mathrm{H}_{2} \mathrm{O}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 44

Determine if each pair of compounds forms a homogeneous solution when combined. For those that form homogeneous solutions, indicate the type of forces that are involved.
a. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3} \mathrm{aHd} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}$
$\mathrm{b} . \mathrm{CBr}_{4} \mathrm{and} \mathrm{H}_{2} \mathrm{O}$
c. LiNO $_{3}$ and $\mathrm{H}_{2} \mathrm{O}$
d. $\mathrm{CH}_{3} \mathrm{OH}$ and $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{3}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 45

Which compound would you expect to have greater surface tension:
acetone $\left[\left[\mathrm{CH}_{3}\right)_{2} \mathrm{CO}\right]$ or water $\left(\mathrm{H}_{2} \mathrm{O}\right)$ ? Explain.

Ahmed Ali

Numerade Educator

Problem 46

Water (a) "wets" some surfaces and beads up on others. Mercury (b)
in contrast, beads up on almost all surfaces. Explain this
difference.

Ahmed Ali

Numerade Educator

Problem 47

The structures of two isomers of heptane are shown here. Which
of these two compounds would you expect to have the greater
viscosity?

Ahmed Ali

Numerade Educator

Problem 48

The viscosity of a multigrade motor oil (such as one rated $10 \mathrm{W}-40$ ) is
less temperature dependent than the viscosities of most substances.
These oils contain polymers (long molecules composed of repeating
units. that coil up at low temperatures, but unwind at higher temperatures. Explain how the addition of these polymers to the motor oil might make the viscosity less temperature dependent than a normal
liquid.

Nicholas White

Numerade Educator

Problem 49

Water in a glass tube that contains grease or oil residue displays a flat
meniscus (the tube on the left in the accompanying photo), whereas
water in a clean glass tube displays a concave meniscus (the tube on
the right). Explain this observation.

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 50

When a thin glass tube is put into water, the water rises 1.4 $\mathrm{cm}$ .
When the same tube is put into hexane, the hexane rises only 0.4 $\mathrm{cm}$ .
Explain.

RD

Ryan Daly

Numerade Educator

Problem 51

Which evaporates more quickly: 55 $\mathrm{mL}$ of water in a beaker with a
diameter of $4.5 \mathrm{cm},$ or 55 $\mathrm{mL}$ of water in a dish with a diameter of
112 $\mathrm{cm}^{2}$ Is the vapor pressure of the water different in the two containers?
Explain.

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 52

Which evaporates more quickly: 55 $\mathrm{mL}$ of water $\left(\mathrm{H}_{2} \mathrm{O}\right)$ in a beaker or
55 $\mathrm{mL}$ of acetone $\left[\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CO}\right]$ in an identical beaker under identical
conditions? Is the vapor pressure of the two substances different?
Explain.

RD

Ryan Daly

Numerade Educator

Problem 53

Spilling room-temperature water your skin on a hot day cools you
down. Spilling room-temperature vegetable oil over your skin on a hot
day does not. Explain the difference.

Ahmed Ali

Numerade Educator

Problem 54

Why is the heat of vaporization of water greater at room temperature
than it is at its boiling point?

RD

Ryan Daly

Numerade Educator

Problem 55

The human body obtains 915 $\mathrm{kJ}$ of energy from a candy bar. If
this energy were used to vaporize water at $100.0^{\circ} \mathrm{C},$ how much
water (in liters) could be vaporized? (Assume the density of water is
1.00 $\mathrm{g} / \mathrm{mL} .$ .

Ahmed Ali

Numerade Educator

Problem 56

A 100.0 $\mathrm{mL}$ sample of water is heated to its boiling point. How
much heat (in kJ) is required to vaporize it? (Assume a density of
1.00 $\mathrm{g} / \mathrm{mL} . )$

Ahmed Ali

Numerade Educator

Problem 57

Suppose that 0.95 gof water condenses on a 75.0 g block of iron that is
initially at $22^{\circ} \mathrm{C} .$ If the heat released during condensation is used only to warm the iron block, what is the final temperature (in $^{\circ} \mathrm{C} )$ of the
iron block? (Assume a constant enthalpy of vaporization for water of
44.0 $\mathrm{k} / \mathrm{mol} .$ .

ML

Marcus Liebenthal

Numerade Educator

Problem 58

Suppose that 1.15 g of rubbing alcohol $\left(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}\right)$ evaporates from a
65.0 $\mathrm{g}$ aluminum block. If the aluminum block is initially at $25^{\circ} \mathrm{C}$ ,
what is the final temperature of the block after the evaporation of the alcohol? Assume that the heat required for the vaporization of the alcohol comes only from the aluminum block and that the alcohol vaporizes at $25^{\circ} \mathrm{C}$ .

Ahmed Ali

Numerade Educator

Problem 59

This table displays the vapor pressure of ammonia at several different
temperatures. Use the data to determine the heat of vaporization and
normal boiling point of ammonia.

Ahmed Ali

Numerade Educator

Problem 60

This table displays the vapor pressure of nitrogen at several different
temperatures. Use the data to determine the heat of vaporization and
normal boiling point of nitrogen.

Ahmed Ali

Numerade Educator

Problem 61

Ethanol has a heat of vaporization of 38.56 $\mathrm{kJ} / \mathrm{mol}$ and a normal
boiling point of $78.4^{\circ} \mathrm{C}$ . What is the vapor pressure of ethanol
at $15^{\circ} \mathrm{C} ?$

Ahmed Ali

Numerade Educator

Problem 62

Benzene has a heat of vaporization of 30.72 $\mathrm{kJ} / \mathrm{mol}$ and a normal boiling point of $80.1^{\circ} \mathrm{C}$ . At what temperature does benzene boil when the
external pressure is 445 torr?

Ahmed Ali

Numerade Educator

Problem 63

How much energy is released when 65.8 of water freezes?

Ahmed Ali

Numerade Educator

Problem 64

Calculate the amount of heat required to completely sublime 50.0 $\mathrm{g}$ of
solid dry ice $\left(\mathrm{CO}_{2}\right)$ at its sublimation temperature. The heat of sublimation for carbon dioxide is 32.3 $\mathrm{k} / \mathrm{mol}$ .

Ahmed Ali

Numerade Educator

Problem 65

An 8.5 g ice cube is placed into 255 g of water. Calculate the temperature change in the water upon the complete melting of the ice. Assume
that all of the energy required to melt the ice comes from the water.

Lucas Pressley

Numerade Educator

Problem 66

How much ice (in grams) would have to melt to lower the temperature
of 352 $\mathrm{mL}$ of water from $25^{\circ} \mathrm{C}$ to $5^{\circ} \mathrm{C}$ ? (Assume the density of water is
1.0 $\mathrm{g} / \mathrm{ml.}$

RD

Ryan Daly

Numerade Educator

Problem 67

How much heat (in $\mathrm{kJ} )$ is required to warm 10.0 $\mathrm{g}$ of ice, initially at
$-10.0^{\circ} \mathrm{C},$ to steam at $110.0^{\circ} \mathrm{C} ?$ The heat capacity of ice is 2.09 $\mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C}$ and that of steam is 2.01 $\mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 68

How much heat (in kJ) is evolved in converting 1.00 mol of steam at
$145^{\circ} \mathrm{C}$ to ice at $-50^{\circ} \mathrm{C} ?$ The heat capacity of steam is $2.01 \mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C},$ and
that of ice is 2.09 $\mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C}$ .

Dominique Jan Tan

Dominique Jan Tan

Numerade Educator

Problem 69

Water has a high boiling point given its relatively low molar mass.
Explain.

Ahmed Ali

Numerade Educator

Problem 70

Water is a good solvent for many substances. What is the molecular basis
for this property, and why is it significant?

Ahmed Ali

Numerade Educator

Problem 71

Explain the role water plays in moderating Earth's climate.

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 72

How is the density of solid water compared to that of liquid water atypical among substances? Why is this significant?

Ahmed Ali

Numerade Educator

Problem 73

Explain the observed trend in the melting points of the hydrogen halides.
$$
\begin{array}{ll}{\mathrm{HI}} & {-50.8^{\circ} \mathrm{C}} \\ {\mathrm{HBr}} & {-88.5^{\circ} \mathrm{C}} \\ {\mathrm{HCl}} & {-114.8^{\circ} \mathrm{C}} \\ {\mathrm{HF}} & {-83.1^{\circ} \mathrm{C}}\end{array}
$$

Ahmed Ali

Numerade Educator

Problem 74

Explain the observed trend in the boiling points of these compounds.
$$
\begin{array}{ll}{\mathrm{H}_{2} \mathrm{Te}} & {-2^{\circ} \mathrm{C}} \\ {\mathrm{H}_{2} \mathrm{Se}} & {-41.5^{\circ} \mathrm{C}} \\ {\mathrm{H}_{2} \mathrm{S}} & {-60.7^{\circ} \mathrm{C}} \\ {\mathrm{H}_{2} \mathrm{O}} & {-100^{\circ} \mathrm{C}}\end{array}
$$

Ahmed Ali

Numerade Educator

Problem 75

The vapor pressure of water at $25^{\circ} \mathrm{C}$ is 23.76 torr. If 1.25 g of water is
enclosed in a 1.5 $\mathrm{L}$ container, is any liquid present? If so, what is the
mass of the liquid?

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 76

The vapor pressure of $\mathrm{CCl}_{3} \mathrm{F}$ at 300 $\mathrm{K}$ is 856 torr. If 11.5 $\mathrm{g}$ of $\mathrm{CCl}_{3} \mathrm{F}$
is enclosed in a 1.0 $\mathrm{L}$ container, is any liquid present? If so, what is the
mass of the liquid?

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 77

Four ice cubes at exactly $0^{\circ} \mathrm{C}$ with a total mass of 53.5 $\mathrm{g}$ are combined with 115 $\mathrm{g}$ of water at $75^{\circ} \mathrm{C}$ in an insulated container. If no
heat is lost to the surroundings, what is the final temperature of the
mixture?

Ahmed Ali

Numerade Educator

Problem 78

A sample of steam with a mass of 0.552 g at a temperature of $100^{\circ} \mathrm{C}$
condenses into an insulated container holding 4.25 g of water at
$5.0^{\circ} \mathrm{C}$ . Assuming that no heat is lost to the surroundings, what is the
final temperature of the mixture?

Ahmed Ali

Numerade Educator

Problem 79

Draw a heating curve (such as the one in Figure 12.33 ) for 1 mole of
methanol beginning at 170 $\mathrm{K}$ and ending at 350 $\mathrm{K}$ . Assume that the
values given here are constant over the relevant temperature ranges.

MS

Michael Smith

Numerade Educator

Problem 80

Draw a heating curve (surve (such as the one in Figure 12.33$)$ for 1 mole of
benzene beginning at $0^{\circ} \mathrm{C}$ and ending at $100^{\circ} \mathrm{C}$ . Assume that the values given here are constant over the relevant temperature ranges.

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 81

Air conditioners not only cool air, but dry it as well. A room in a home
measures 6.0 $\mathrm{m} \times 10.0 \mathrm{m} \times 2.2 \mathrm{m} .$ If the outdoor temperature is
$30^{\circ} \mathrm{C}$ and the vapor pressure of water in the air is 85$\%$ of the vapor
pressure of water at this temperature, what mass of water must be removed from the air each time volume of air in the room cycles
through the air conditioner? The vapor pressure for water at $30^{\circ} \mathrm{C}$ is
31.8 torr.

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 82

A sealed flask contains 0.55 g of water at 28 'C. The vapor pressure of
water at this temperature is 28.36 mmHg. What is the minimum volume of the flask in order that there is no liquid water present in the
flask?

Nicholas White

Numerade Educator

Problem 83

Two liquids, A and $\mathrm{B}$ , have vapor pressures at a given temperature of
24 $\mathrm{mm} \mathrm{Hg}$ and 36 $\mathrm{mm} \mathrm{Hg}$ , respectively. We prepare solutions of $\mathrm{A}$ and
$\mathrm{B}$ at a given temperature and measure the total pressures above the solutions. We obtain these data: Predict the total pressure above a solution of 5 mol $A$ and 1 mol $B$ .

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 84

Butane $\left(\mathrm{C}_{4} \mathrm{H}_{10}\right)$ has a heat of vaporization of 22.44 $\mathrm{kk} / \mathrm{mol}$ and a nor-
mal boiling point of $-0.4^{\circ} \mathrm{C} . \mathrm{A} 250.0 \mathrm{mL}$ sealed flask contains 0.55 $\mathrm{g}$
of butane at $-22^{\circ} \mathrm{C}$ . How much liquid butane is present? If the butane
is warmed to $25^{\circ} \mathrm{C}$ , how much liquid butane is present?

Noah Barguez-Arias

Noah Barguez-Arias

Numerade Educator

Problem 85

Liquid nitrogen can be used as a cryogenic substance to obtain
low temperatures. Under atmospheric pressure, liquid nitrogen boils at 77 $\mathrm{K}$ , allowing low temperatures to be reached. However,
if the nitrogen is placed in a sealed, insulated container connected to
a vacuum pump, even lower temperatures can be reached. Why? If the vacuum pump has sufficient capacity and is left on
for an extended period of time, the liquid nitrogen starts to freeze.
Explain.

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 86

Given that the heat of fusion of water is $-6.02 \mathrm{kJ} / \mathrm{mol}$ , the heat capacity
of $\mathrm{H}_{2} \mathrm{O}(l)$ is 75.2 $\mathrm{J} / \mathrm{mol} \cdot \mathrm{K}$ , and the heat capacity of $\mathrm{H}_{2} \mathrm{O}(s)$ is
37.7 $\mathrm{J} / \mathrm{mol} \cdot \mathrm{K}$ , calculate the heat of fusion of water at $-10^{\circ} \mathrm{C} .$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 87

The heat of combustion of $\mathrm{CH}_{4}$ is $890.4 \mathrm{kJ} / \mathrm{mol},$ and the heat capacity of
$\mathrm{H}_{2} \mathrm{O}$ is 75.2 $\mathrm{J} / \mathrm{mol} \cdot \mathrm{K}$ . Find the volume of methane measured at 298 $\mathrm{K}$
and 1.00 atm required to convert 1.00 $\mathrm{L}$ of water at 298 $\mathrm{K}$ to water vapor
at 373 $\mathrm{K}$ .

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 88

Three 1.0 L flasks, maintained at 308 $\mathrm{K}$ , are connected to each other with stopcocks. Initially the stopcocks are closed. One of the flasks contains 1.0 atm of $\mathrm{N}_{2} ;$ the second, 2.0 $\mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O} ;$ and the third, 0.50 $\mathrm{g}$ of ethanol, $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O} .$ The vapor pressure of $\mathrm{H}_{2} \mathrm{O}$ at 308 $\mathrm{K}$ is $42 \mathrm{mm} \mathrm{Hg},$ and that of ethanol is 102 $\mathrm{mmHg} .$ When the stopcocks are opened and the contents mix freely, what is the pressure?

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 89

One prediction of global warming is the melting of global ice, which
may result in coastal flooding. A criticism of this prediction is that the
melting of icebergs does not increase ocean levels any more than the
melting of ice in a glass of water increases the level of liquid in the glass. Is this a valid criticism? Does the melting of an ice cube in a cup
of water raise the level of the liquid in the cup? Why or why not? In
response to this criticism, scientists have asserted that they are not
worried about melting icebergs, but rather the melting of ice sheets that sit on the continent of Antarctica. Would the melting of this ice
increase ocean levels? Why or why not?

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 90

The rate of vaporization depends on the surface area of the liquid.
However, the vapor pressure of a liquid does not depend on the surface
area. Explain.

Ahmed Ali

Numerade Educator

Problem 91

Substance A has a smaller heat of vaporization than substance $\mathrm{B}$ .
Which of the two substances undergoes a larger change in vapor pressure for a given change in temperature?

Lizabeth Tumminello

Lizabeth Tumminello

Numerade Educator

Problem 92

A substance has a heat of vaporization of $\Delta H_{\text { ap }}$ and heat of fusion of $\Delta H_{\text { fus. }} .$ Express the heat of sublimation in terms of $\Delta H_{\text { vap }}$ and $\Delta H_{\text { fus }}$

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 93

Examine the heating curve for water in Section 12.7 (Figure 12.33$) .$ If heat
is added to the water at a constant rate, which of the three segments in
which temperature is rising will have the least steep slope? Why?

Catherine Lemar

Catherine Lemar

Numerade Educator

Problem 94

A root cellar is an underground chamber used to store fruits, vegetables,
and sometimes meats. In extreme cold, farmers put large vats of water
into the root cellar to prevent fruits and vegetables from freezing. Explain
why this works.

Nicholas White

Numerade Educator

Problem 95

Suggest an explanation for the observation that the heat of fusion of a
substance is always smaller than its heat of vaporization.

Ahmed Ali

Numerade Educator

Problem 96

Refer to Figure 12.33 to answer each question.
a. A sample of steam begins on the line segment labeled 5 on the graph. Is heat absorbed or released in moving from the line segment labeled 5 to the line segment labeled 3$?$ What is the sign of $q$ for this change?
b. In moving from left to right along the line segment labeled 2 on the graph, heat is absorbed, but the temperature remains constant. Where does the heat go?
c. How would the graph change if it were for another substance (other than water)?

Nicholas White

Numerade Educator

Problem 97

The following image is an electrostatic potential map for ethylene
oxide, $\left(\mathrm{CH}_{2}\right)_{2} \mathrm{O},$ a polar molecule. Use the electrostatic potential map to predict the geometry for how one ethylene oxide molecule interacts
with another. Draw structural formulas, using the three-dimensional
bond notation introduced in Section $6.9,$ to show the geometry of the
interaction.

Snow Popis

Numerade Educator