General Chemistry

Darrell D. Ebbing, Steven D. Gammon

Chapter 11

States of Matter; Liquids and Solids - all with Video Answers

Educators

Chapter Questions

Problem 1

List the different phase transitions that are possible and give examples of each.

Natalie Johns

Natalie Johns

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Problem 2

Describe how you could purify iodine by sublimation.

Natalie Johns

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Problem 3

Describe vapor pressure in molecular terms. What do we mean by saying it involves a dynamic equilibrium?

Natalie Johns

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Problem 4

Explain why $15 \mathrm{~g}$ of steam at $100^{\circ} \mathrm{C}$ melts more ice than $15 \mathrm{~g}$ of liquid water at $100^{\circ} \mathrm{C}$.

Tianyu Li

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Problem 5

Why is the heat of fusion of a substance smaller than its heat of vaporization?

Courtney R

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Problem 6

Explain why evaporation leads to cooling of the liquid.

Tianyu Li

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Problem 7

Describe the behavior of a liquid and its vapor in a closed vessel as the temperature increases.

Natalie Johns

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Problem 8

Gases that cannot be liquefied at room temperature merely by compression are called "permanent" gases. How could you liquefy such a gas?

Tianyu Li

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Problem 9

The pressure in a cylinder of nitrogen continuously decreases as gas is released from it. On the other hand, a cylinder of propane maintains a constant pressure as propane is released. Explain this difference in behavior.

Tianyu Li

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Problem 10

Why does the vapor pressure of a liquid depend on the intermolecular forces?

Natalie Johns

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Problem 11

Explain the surface tension of a liquid in molecular terms. How does the surface tension make a liquid act as though it had a "skin"?

Natalie Johns

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Problem 12

Explain the origin of the London force that exists between two molecules.

Natalie Johns

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Problem 13

Explain what is meant by hydrogen bonding. Describe the hydrogen bonding between two $\mathrm{H}_{2} \mathrm{O}$ molecules.

Natalie Johns

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Problem 14

Why do molecular substances have relatively low melting points?

Natalie Johns

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Problem 15

Describe the distinguishing characteristics of a crystalline solid and an amorphous solid.

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Problem 16

Describe the face-centered cubic unit cell.

Tianyu Li

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Problem 17

Describe the structure of thallium(I) iodide, which has the same structure as cesium chloride.

Tianyu Li

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Problem 18

What is the coordination number of $\mathrm{Cs}^{+}$ in $\mathrm{CsCl}$ ? of $\mathrm{Na}^{+}$ in $\mathrm{NaCl}$ ? of $\mathrm{Zn}^{2+}$ in $\mathrm{ZnS} ?$

Tianyu Li

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Problem 19

Explain in words how Avogadro's number could be obtained from the unit-cell edge length of a cubic crystal. What other data are required?

Tianyu Li

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Problem 20

Explain the production of an x-ray diffraction pattern by a crystal in terms of the interference of waves.

Natalie Johns

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Problem 21

Shown here is a curve of the distribution of kinetic energies of the molecules in a liquid at an arbitrary temperature $T$.
The lines marked $\mathrm{A}, \mathrm{B}$, and $\mathrm{C}$ represent the point where each of the molecules for three different liquids (liquid A, liquid $\mathrm{B}$, and liquid $\mathrm{C}$ ) has enough kinetic energy to escape into the gas phase (see Figure $11.5$ for more information). Write a brief explanation for each of your answers to the following questions.
a. Which of the molecules $-\mathrm{A}, \mathrm{B}$, or $\mathrm{C}-$ would have the majority of the molecules in the gas phase at temperature $T ?$
b. Which of the molecules $-\mathrm{A}, \mathrm{B}$, or $\mathrm{C}-$ has the strongest intermolecular attractions?
c. Which of the molecules would have the lowest vapor pressure at temperature $T$ ?

Tianyu Li

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Problem 22

Consider a substance $X$ with a $\Delta H_{v a p}=20.3 \mathrm{~kJ} / \mathrm{mol}$ and $\Delta H_{f u s}=9.0 \mathrm{~kJ} / \mathrm{mol}$. The melting point, freezing point, and heat capacities of both the solid and liquid $\mathrm{X}$ are identical to those of water.
a. If you place one beaker containing $50 \mathrm{~g}$ of $\mathrm{X}$ at $-10^{\circ} \mathrm{C}$ and another beaker with $50 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O}$ at $-10^{\circ} \mathrm{C}$ on a hot plate and start heating them, which material will reach the boiling point first?
b. Which of the materials from part a, $X$ or $\mathrm{H}_{2} \mathrm{O}$, would completely boil away first?
c. On a piece of graph paper, draw the heating curve for $\mathrm{H}_{2} \mathrm{O}$ and $\mathrm{X}$. How do the heating curves reflect your answers from parts a and b?

Lottie Adams

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Problem 23

Using the information presented in this chapter, explain why farmers spray water above and on their fruit trees on still nights when they know the temperature is going to drop below $0^{\circ} \mathrm{C}$. (Hint: Totally frozen fruit is what the farmers are trying to avoid.)

Natalie Johns

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Problem 24

You are presented with three bottles, each containing a different liquid: bottle $\mathrm{A}$, bottle $\mathrm{B}$, and bottle $\mathrm{C}$. Bottle A's label states that it is an ionic compound with a boiling point of $35^{\circ} \mathrm{C}$. Bottle B's label states that it is a molecular compound with a boiling point of $29.2^{\circ} \mathrm{C}$. Bottle C's label states that it is a molecular compound with a boiling point of $67.1^{\circ} \mathrm{C}$.
a. Which of the compounds is most likely to be incorrectly identified?
b. If Bottle A were a molecular compound, which of the compounds has the strongest intermolecular attractions?
c. If Bottle A were a molecular compound, which of the compounds would have the highest vapor pressure?

Tianyu Li

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Problem 25

Shown here is a representation of a unit cell for a crystal. The orange balls are atom A, and the grey balls are atom $\mathrm{B}$.
a. What is the chemical formula of the compound that has this unit cell $\left(\mathrm{A}_{2} \mathrm{~B}_{2}\right) ?$
b. Consider the configuration of the $\mathrm{A}$ atoms. Is this a cubic unit cell? If so, which type?

Crystal Wang

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Problem 26

Assuming normal winter conditions $\left(-1.5^{\circ} \mathrm{C}\right.$ and $1.0$ atm pressure), consult the phase diagram for water (Figure $11.11$ ) and come up with a reason why ice skates and sleds slide so well on solid water. Keep in mind that sleds and ice skates do not typically slide well on other solid surfaces (concrete and metal, for example).

Adriano Chikande

Adriano Chikande

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Problem 27

If you place room temperature water in a wellinsulated cup and allow some of the water to evaporate, the temperature of the water in the cup will drop lower than room temperature. Come up with an explanation for this observation.

Natalie Johns

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Problem 28

The heats of vaporization for water and carbon disulfide are $40.7 \mathrm{~kJ} / \mathrm{mol}$ and $26.8 \mathrm{~kJ} / \mathrm{mol}$, respectively. A vapor (steam) burn occurs when the concentrated vapor of a substance condenses on your skin. Which of these substances, water or carbon disulfide, will result in the most severe burn if

Tianyu Li

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Problem 29

When hypothetical element $X$ forms a solid, it can crystallize in three ways: with unit cells being either simple cubic, face-centered cubic, or body-centered cubic.
a. Which crystalline form of solid $X$ has the highest density?
b. Which crystalline form of solid $X$ has the most empty space?

Sima Sarker

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Problem 30

Consider two flasks that each contains different pure liquids at $20^{\circ} \mathrm{C}$. The liquid in one flask, substance $A$, has a molar mass of $100 \mathrm{~g} / \mathrm{mol}$ and has hydrogen bonding. The liquid in the other flask, substance $\mathrm{B}$, has a molar mass of $105 \mathrm{~g} / \mathrm{mol}$ and has dipole-dipole interactions.
a. If the molecular structures of the compounds are very similar, which flask likely contains substance $\mathrm{A}$ ?
b. If you were to increase the temperature of each of the flasks by $15^{\circ} \mathrm{C}$, how would the pictures change (assume that you stay below the boiling points of the liquids)?

Tianyu Li

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Problem 31

Identify the phase transition occurring in each of the following.
a. The water level in an aquarium tank falls continuously (the tank has no leak).
b. A mixture of scrambled eggs placed in a cold vacuum chamber slowly turns to a powdery solid.
c. Chlorine gas is passed into a very cold test tube where it turns to a yellow liquid.
d. When carbon dioxide gas under pressure exits from a small orifice, it turns to a white "snow."
e. Molten lava from a volcano cools and turns to solid rock.

Natalie Johns

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Problem 32

Identify the phase transition occurring in each of the following.
a. Mothballs slowly become smaller and eventually disappear.
b. Rubbing alcohol spilled on the palm of the hand feels cool as the volume of liquid decreases.
c. A black deposit of tungsten metal collects on the inside of a lightbulb whose filament is tungsten metal.

Natalie Johns

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Problem 33

Use Figure $11.7$ to estimate the boiling point of diethyl ether, $\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \mathrm{O}$, under an external pressure of $350 \mathrm{mmHg}$.
11.34 Use Figure $11.7$ to estimate the boiling point of carbon tetrachloride, $\mathrm{CCl}_{4}$, under an external pressure of $250 \mathrm{mmHg}$.

Crystal Wang

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Problem 34

Use Figure $11.7$ to estimate the boiling point of carbon tetrachloride, $\mathrm{CCl}_{4}$, under an external pressure of $250 \mathrm{mmHg}$.

Tianyu Li

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Problem 35

An electric heater coil provided heat to a $15.5-\mathrm{g}$ sample of iodine, $\mathrm{I}_{2}$, at the rate of $3.48 \mathrm{~J} / \mathrm{s}$. It took $4.54 \mathrm{~min}$ from the time the iodine began to melt until the iodine was completely melted. What is the heat of fusion per mole of iodine?

Tianyu Li

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Problem 36

A $35.8-\mathrm{g}$ sample of cadmium metal was melted by an electric heater providing $4.66 \mathrm{~J} / \mathrm{s}$ of heat. If it took $6.92 \mathrm{~min}$ from the time the metal began to melt until it was completely melted, what is the heat of fusion per mole of cadmium?

Tianyu Li

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Problem 37

Isopropyl alcohol, $\mathrm{CH}_{3} \mathrm{CHOHCH}_{3}$, is used in rubbing alcohol mixtures. Alcohol on the skin cools by evaporation. How much heat is absorbed by the alcohol if $2.25 \mathrm{~g}$ evaporates? The heat of vaporization of isopropyl alcohol is $42.1$ $\mathrm{kJ} / \mathrm{mol}$.

Sima Sarker

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Problem 38

Liquid butane, $\mathrm{C}_{4} \mathrm{H}_{10}$, is stored in cylinders to be used as a fuel. Suppose $39.3 \mathrm{~g}$ of butane gas is removed from a cylinder. How much heat must be provided to vaporize this much gas? The heat of vaporization of butane is $21.3 \mathrm{~kJ} / \mathrm{mol}$.

Crystal Wang

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Problem 39

Water at $0^{\circ} \mathrm{C}$ was placed in a dish inside a vessel maintained at low pressure by a vacuum pump. After a quantity of water had evaporated, the remainder froze. If $9.31 \mathrm{~g}$ of ice at $0^{\circ} \mathrm{C}$ was obtained, how much liquid water must have evaporated? The heat of fusion of water is $6.01 \mathrm{~kJ} / \mathrm{mol}$ and its heat of vaporization is $44.9 \mathrm{~kJ} / \mathrm{mol}$ at $0^{\circ} \mathrm{C}$.

Tianyu Li

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Problem 40

A quantity of ice at $0.0^{\circ} \mathrm{C}$ was added to $33.6 \mathrm{~g}$ of water at $21.0^{\circ} \mathrm{C}$ to give water at $0.0^{\circ} \mathrm{C}$. How much ice was added? The heat of fusion of water is $6.01 \mathrm{~kJ} / \mathrm{mol}$ and the specific heat is $4.18 \mathrm{~J} /\left(\mathrm{g} \cdot{ }^{\circ} \mathrm{C}\right)$

Tianyu Li

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Problem 41

A quantity of ice at $0^{\circ} \mathrm{C}$ is added to $64.3 \mathrm{~g}$ of water in a glass at $55^{\circ} \mathrm{C}$. After the ice melted, the temperature of the water in the glass was $15^{\circ} \mathrm{C}$. How much ice was added? The heat of fusion of water is $6.01 \mathrm{~kJ} / \mathrm{mol}$ and the specific heat is $4.18$ $\mathrm{J} /\left(\mathrm{g} \cdot{ }^{\circ} \mathrm{C}\right)$

Tianyu Li

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Problem 42

Steam at $100^{\circ} \mathrm{C}$ was passed into a flask containing $275 \mathrm{~g}$ of water at $21^{\circ} \mathrm{C}$, where the steam condensed. How many grams of steam must have condensed if the temperature of the water in the flask was raised to $83{ }^{\circ} \mathrm{C} ?$ The heat of vaporization of water at $100^{\circ} \mathrm{C}$ is $40.7 \mathrm{~kJ} / \mathrm{mol}$ and the specific heat is $4.18 \mathrm{~J} /\left(\mathrm{g} \cdot{ }^{\circ} \mathrm{C}\right)$

Tianyu Li

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Problem 43

Chloroform, $\mathrm{CHCl}_{3}$, a volatile liquid, was once used as an anesthetic but has been replaced by safer compounds. Chloroform boils at $61.7^{\circ} \mathrm{C}$ and has a heat of vaporization of $31.4 \mathrm{~kJ} / \mathrm{mol}$. What is its vapor pressure at $36.2^{\circ} \mathrm{C}$ ?

Crystal Wang

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Problem 44

Methanol, $\mathrm{CH}_{3} \mathrm{OH}$, a colorless, volatile liquid, was formerly known as wood alcohol. It boils at $65.0^{\circ} \mathrm{C}$ and has a heat of vaporization of $37.4 \mathrm{~kJ} / \mathrm{mol}$. What is its vapor pressure at $22.0^{\circ} \mathrm{C}$ ?

Tianyu Li

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Problem 45

White phosphorus, $\mathrm{P}_{4}$, is normally a white, waxy solid melting at $44^{\circ} \mathrm{C}$ to a colorless liquid. The liquid has a vapor pressure of $400.0 \mathrm{mmHg}$ at $251.0^{\circ} \mathrm{C}$ and $760.0 \mathrm{mmHg}$ at $280.0^{\circ} \mathrm{C}$. What is the heat of vaporization of this substance?

Tianyu Li

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Problem 46

Carbon disulfide, $\mathrm{CS}_{2}$, is a volatile, flammable liquid. It has a vapor pressure of $400.0 \mathrm{mmHg}$ at $28.0^{\circ} \mathrm{C}$ and $760.0$ $\mathrm{mmHg}$ at $46.5^{\circ} \mathrm{C}$. What is the heat of vaporization of this substance?

Tianyu Li

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Problem 47

Shown here is the phase diagram for compound $Z$. The triple point of $Z$ is $-5.1^{\circ} \mathrm{C}$ at $3.3$ atm and the critical point is $51^{\circ} \mathrm{C}$ and $99.1 \mathrm{~atm} .$ a. What is the state of $Z$ at position $A ?$
b. If we increase the temperature from the compound at position A to $60^{\circ} \mathrm{C}$ while holding the pressure constant, what is the state of $Z$ ?
c. If we take the compound starting under the conditions of part b and reduce the temperature to $20^{\circ} \mathrm{C}$ and increase the pressure to $65 \mathrm{~atm}$, what is the state of $\mathrm{Z}$ ?
d. Would it be possible to make the compound starting under the conditions of part $\mathrm{c}$ a solid by increasing just the pressure?

Tianyu Li

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Problem 48

Shown here is the phase diagram for compound X. The triple point of $X$ is $-25.1^{\circ} \mathrm{C}$ at $0.50 \mathrm{~atm}$ and the critical point is $22^{\circ} \mathrm{C}$ and $21.3 \mathrm{~atm}$.
a. What is the state of $X$ at position $A$ ?
b. If we decrease the temperature from the compound at position A to $-28.2^{\circ} \mathrm{C}$ while holding the pressure constant, what is the state of $\mathrm{X}$ ?
c. If we take the compound starting under the conditions of part b and increase the temperature to $15.3^{\circ} \mathrm{C}$ and decrease the pressure to $0.002 \mathrm{~atm}$, what is the state of $\mathrm{X}$ ?
d. Would it be possible to make the compound starting under the conditions of part c a solid by increasing just the pressure?

Crystal Wang

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Problem 49

Use graph paper and sketch the phase diagram of oxygen, $\mathrm{O}_{2}$, from the following information: normal melting point, $-218^{\circ} \mathrm{C} ;$ normal boiling point,$-183^{\circ} \mathrm{C} ;$ triple point, $-219^{\circ} \mathrm{C}$, $1.10 \mathrm{mmHg} ;$ critical point, $-118^{\circ} \mathrm{C}, 50.1$ atm. Label each phase region on the diagram.

Natalie Johns

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Problem 50

Use graph paper and sketch the phase diagram of argon, Ar, from the following information: normal melting point, $-187^{\circ} \mathrm{C} ;$ normal boiling point, $-186^{\circ} \mathrm{C}$; triple point, $-189^{\circ} \mathrm{C}, 0.68$ atm; critical point, $-122^{\circ} \mathrm{C}, 48$ atm. Label each phase region on the diagram.

Natalie Johns

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Problem 51

Which of the following substances can be liquefied by applying pressure at $25^{\circ} \mathrm{C} ?$ For those that cannot, describe the conditions under which they can be liquefied.

Tianyu Li

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Problem 52

A tank of gas at $21^{\circ} \mathrm{C}$ has a pressure of $1.0 \mathrm{~atm}$. Using the data in the table, answer the following questions. Explain your answers.
a. If the tank contains carbon tetrafluoride, $\mathrm{CF}_{4}$, is the liquid state also present?
b. If the tank contains butane, $\mathrm{C}_{4} \mathrm{H}_{10}$, is the liquid state also present?

Crystal Wang

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Problem 53

Bromine, $\mathrm{Br}_{2}$, has a triple point at $-7.3^{\circ} \mathrm{C}$ and 44 $\mathrm{mm} \mathrm{Hg}$ and a critical point at $315^{\circ} \mathrm{C}$ and $102 \mathrm{~atm}$. The density of the solid is $3.4 \mathrm{~g} / \mathrm{cm}^{3}$, and the density of the liquid is $3.1$ $\mathrm{g} / \mathrm{cm}^{3} .$ Sketch a rough phase diagram of bromine, labeling all important features. Circle the correct word in each of the following sentences (and explain your answers).
a. Bromine vapor at $40 \mathrm{mmHg}$ condenses to the (liquid, solid) when cooled sufficiently.
b. Bromine vapor at $400 \mathrm{mmHg}$ condenses to the (liquid, solid) when cooled sufficiently.

Tianyu Li

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Problem 54

Krypton, $\mathrm{Kr}$, has a triple point at $-169^{\circ} \mathrm{C}$ and $133 \mathrm{mmHg}$ and a critical point at $-63^{\circ} \mathrm{C}$ and $54 \mathrm{~atm}$. The density of the solid is $2.8 \mathrm{~g} / \mathrm{cm}^{3}$, and the density of the liquid is $2.4 \mathrm{~g} / \mathrm{cm}^{3}$. Sketch a rough phase diagram of krypton. Circle the correct word in each of the following sentences (and explain your answers).
a. Solid krypton at $130 \mathrm{mmHg}$ (melts, sublimes without melting) when the temperature is raised.
b. Solid krypton at $760 \mathrm{mmHg}$ (melts, sublimes without melting) when the temperature is raised.

Tianyu Li

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Problem 55

The heats of vaporization of liquid $\mathrm{Cl}_{2}$, liquid $\mathrm{H}_{2}$, and liquid $\mathrm{N}_{2}$ are $20.4 \mathrm{~kJ} / \mathrm{mol}, 0.9 \mathrm{~kJ} / \mathrm{mol}$, and $5.6 \mathrm{~kJ} / \mathrm{mol}$, respectively. Are the relative values as you would expect? Explain.

Crystal Wang

Numerade Educator

Problem 56

The heats of vaporization of liquid $\mathrm{O}_{2}$, liquid Ne, and liquid methanol, $\mathrm{CH}_{3} \mathrm{OH}$, are $6.8 \mathrm{~kJ} / \mathrm{mol}, 1.8 \mathrm{~kJ} / \mathrm{mol}$, and
$34.5 \mathrm{~kJ} / \mathrm{mol}$, respectively. Are the relative values as you would expect? Explain.

Natalie Johns

Numerade Educator

Problem 57

For each of the following substances, list the kinds of intermolecular forces expected.
b. isopropyl alcohol, $\mathrm{CH}_{3} \mathrm{CHOHCH}_{3}$
c. hydrogen iodide, HI
d. krypton, $\mathrm{Kr}$

Natalie Johns

Numerade Educator

Problem 58

11.58 Which of the following compounds would you expect to exhibit only London forces?
a. carbon tetrachloride, $\mathrm{CCl}_{4}$
c. calcium iodide, $\mathbf{C a l}_{2}$
d. phosphorus pentachloride, $\mathrm{PCl}_{5}$

Natalie Johns

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Problem 59

Arrange the following substances in order of increasing magnitude of the London forces: $\mathrm{SiCl}_{4}, \mathrm{CCl}_{4}$, $\mathrm{GeCl}_{4} .$

Natalie Johns

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Problem 60

Arrange the following substances in order of increasing magnitude of the London forces: Ar, He, Kr.

Natalie Johns

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Problem 61

Methane, $\mathrm{CH}_{4}$, reacts with chlorine, $\mathrm{Cl}_{2}$, to produce a series of chlorinated hydrocarbons: methyl chloride $\left(\mathrm{CH}_{3} \mathrm{Cl}\right)$, methylene chloride $\left(\mathrm{CH}_{2} \mathrm{Cl}_{2}\right)$, chloroform (CHCl $\left._{3}\right)$, and carbon tetrachloride $\left(\mathrm{CCl}_{4}\right)$. Which compound has the lowest vapor pressure at room temperature? Explain.

Crystal Wang

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Problem 62

The halogens form a series of compounds with each other, which are called interhalogens. Examples are bromine chloride $(\mathrm{BrCl})$, iodine bromide (IBr), bromine fluoride (BrF), and chlorine fluoride (CIF). Which compound is expected to have the lowest boiling point at any given pressure? Explain.

Crystal Wang

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Problem 63

Predict the order of increasing vapor pressure at a given temperature for the following compounds:
a. $\mathrm{FCH}_{2} \mathrm{CH}_{2} \mathrm{~F}$
b. $\mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{OH}$
c. $\mathrm{FCH}_{2} \mathrm{CH}_{2} \mathrm{OH}$
Explain why you chose this order.

Natalie Johns

Numerade Educator

Problem 64

Predict the order of increasing vapor pressure at a given temperature for the following compounds:
a. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$
b. $\mathrm{HOCH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$
c. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OCH}_{2} \mathrm{CH}_{3}$
Explain why you chose this order.

Natalie Johns

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Problem 65

List the following substances in order of increasing boiling point.

Tianyu Li

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Problem 66

Arrange the following compounds in order of increasing boiling point.

Ian Kaigh

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Problem 67

Classify each of the following by the type of solid it forms: (a) Na; (b) $\mathrm{Fe}$; (c) $\mathrm{B} ;$ (d) $\mathrm{H}_{2} \mathrm{O} ;$ (e) $\mathrm{KF}$.

Natalie Johns

Numerade Educator

Problem 68

Classify each of the following by the type of solid it forms: (a) $\mathrm{LiCl} ;$ (b) $\mathrm{BaCl}_{2}$; (c) $\mathrm{BCl}_{3}$; (d) $\mathrm{CCl}_{4}$; (e) $\mathrm{NCl}_{3}$.

Natalie Johns

Numerade Educator

Problem 69

Classify each of the following solid elements as molecular, metallic, ionic, or covalent network.
a. tin, $\mathrm{Sn}$
b. germanium, Ge
c. sulfur, $\mathrm{S}_{8}$
d. iodine, $\mathrm{I}_{2}$

Natalie Johns

Numerade Educator

Problem 70

Which of the following do you expect to be molecular solids?
a. sodium hydroxide, $\mathrm{NaOH}$
b. solid ethane, $\mathrm{C}_{2} \mathrm{H}_{6}$
c. nickel, $\mathrm{Ni}$
d. solid silane, $\mathrm{SiH}_{4}$

Emily Himsel

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Problem 71

Arrange the following compounds in order of increasing melting point.

Tianyu Li

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Problem 72

Arrange the following substances in order of increasing melting point.

Tianyu Li

Numerade Educator

Problem 73

Associate each type of solid in the left-hand column with two of the properties in the right-hand column. Each property may be used more than once.
a. molecular solid $\quad$ low-melting $\begin{array}{ll}\text { b. ionic solid } & \text { high-melting }\end{array}$
c. metallic solid brittle
d. covalent network $\quad$ malleable solid $\quad$ hard electrically conducting

Crystal Wang

Numerade Educator

Problem 74

On the basis of the description given, classify each of the following solids as molecular, metallic, ionic, or covalent network. Explain your answers.
a. a lustrous, yellow solid that conducts electricity
b. a hard, black solid melting at $2350^{\circ} \mathrm{C}$ to give a nonconducting liquid
c. a nonconducting, pink solid melting at $650^{\circ} \mathrm{C}$ to give an electrically conducting liquid
d. red crystals having a characteristic odor and melting at $171^{\circ} \mathrm{C}$

Natalie Johns

Numerade Educator

Problem 75

Associate each of the solids Co, $\mathrm{LiCl}, \mathrm{SiC}$, and $\mathrm{CHI}_{3}$ with one of the following sets of properties.
a. A white solid melting at $613^{\circ} \mathrm{C} ;$ the liquid is electrically conducting, although the solid is not.
b. A very hard, blackish solid subliming at $2700^{\circ} \mathrm{C}$.
c. A yellow solid with a characteristic odor having a melting point of $120^{\circ} \mathrm{C}$.
d. A gray, lustrous solid melting at $1495^{\circ} \mathrm{C}$; both the solid and liquid are electrical conductors.

Natalie Johns

Numerade Educator

Problem 76

Associate each of the solids $\mathrm{BN}, \mathrm{P}_{4} \mathrm{~S}_{3}, \mathrm{~Pb}$, and $\mathrm{CaCl}_{2}$ with one of the following sets of properties.
a. A bluish-white, lustrous solid melting at $327^{\circ} \mathrm{C}$; the solid is soft and malleable.
b. A white solid melting at $772^{\circ} \mathrm{C}$; the solid is an electrical nonconductor but dissolves in water to give a conducting solution.
c. A yellowish-green solid melting at $172^{\circ} \mathrm{C}$.
d. A very hard, colorless substance melting at about $3000^{\circ} \mathrm{C}$.

Natalie Johns

Numerade Educator

Problem 77

How many atoms are there in a simple cubic unit cell of an atomic crystal in which all atoms are at lattice points?

Tianyu Li

Numerade Educator

Problem 78

How many atoms are there in a body-centered cubic unit cell of an atomic crystal in which all atoms are at lattice points?

Tianyu Li

Numerade Educator

Problem 79

Metallic iron has a body-centered cubic lattice with all atoms at lattice points and a unit cell whose edge length is $286.6 \mathrm{pm}$. The density of iron is $7.87 \mathrm{~g} / \mathrm{cm}^{3}$. What is the mass of an iron atom? Compare this value with the value you obtain from the molar mass.

Tianyu Li

Numerade Educator

Problem 80

Nickel has a face-centered unit cell with all atoms at lattice points and an edge length of $352.4 \mathrm{pm}$. The density of metallic nickel is $8.91 \mathrm{~g} / \mathrm{cm}^{3}$. What is the mass of a nickel atom? From the atomic weight, calculate Avogadro's number.

Tianyu Li

Numerade Educator

Problem 81

Copper metal has a face-centered cubic structure with all atoms at lattice points and a density of $8.93 \mathrm{~g} / \mathrm{cm}^{3} .$ Its atomic weight is $63.5$ amu. Calculate the edge length of the unit cell.

Tianyu Li

Numerade Educator

Problem 82

Barium metal has a body-centered cubic lattice with all atoms at lattice points; its density is $3.51 \mathrm{~g} / \mathrm{cm}^{3}$. From these data and the atomic weight, calculate the edge length of a unit cell.

Tianyu Li

Numerade Educator

Problem 83

Gold has cubic crystals whose unit cell has an edge length of $407.9 \mathrm{pm}$. The density of the metal is $19.3 \mathrm{~g} / \mathrm{cm}^{3}$. From these data and the atomic weight, calculate the number of gold atoms in a unit cell, assuming all atoms are at lattice points. What type of cubic lattice does gold have?

Sima Sarker

Numerade Educator

Problem 84

Chromium forms cubic crystals whose unit cell has an edge length of $288.5 \mathrm{pm}$. The density of the metal is $7.20 \mathrm{~g} / \mathrm{cm}^{3}$. Use these data and the atomic weight to calculate the number of atoms in a unit cell, assuming all atoms are at lattice points. What type of cubic lattice does chromium have?

Tianyu Li

Numerade Educator

Problem 85

Tungsten has a body-centered cubic lattice with all atoms at the lattice points. The edge length of the unit cell is $316.5 \mathrm{pm}$. The atomic weight of tungsten is $183.8$ amu. Calculate its density.

Sima Sarker

Numerade Educator

Problem 86

Lead has a face-centered cubic lattice with all atoms at lattice points and a unit-cell edge length of $495.0 \mathrm{pm}$. Its atomic weight is $207.2$ amu. What is the density of lead?

Tianyu Li

Numerade Educator

Problem 87

Metallic magnesium has a hexagonal close-packed structure and a density of $1.74 \mathrm{~g} / \mathrm{cm}^{3}$. Assume magnesium atoms to be spheres of radius $r$. Because magnesium has a close-packed structure, $74.1 \%$ of the space is occupied by atoms. Calculate the volume of each atom; then find the atomic radius, $r$. The volume of a sphere is equal to $4 \pi r^{3} / 3$.

Sima Sarker

Numerade Educator

Problem 88

Metallic barium has a body-centered cubic structure (all atoms at the lattice points) and a density of $3.51 \mathrm{~g} / \mathrm{cm}^{3}$. Assume barium atoms to be spheres. The spheres in a bodycentered array occupy $68.0 \%$ of the total space. Find the atomic radius of barium. (See Problem 11.87.)

Alex M

Numerade Educator

Problem 89

If you leave your car parked outdoors in the winter, you may find frost on the windows in the morning. If you then start the car and let the heater warm the windows, after some minutes the windows will be dry. Describe all of the phase changes that have occurred.

Tianyu Li

Numerade Educator

Problem 90

Snow forms in the upper atmosphere in a cold air mass that is supersaturated with water vapor. When the snow later falls through a lower, warm air mass, rain forms. When
this rain falls on a sunny spot, the drops evaporate. Describe all of the phase changes that have occurred.

Natalie Johns

Numerade Educator

Problem 91

The percent relative humidity of a sample of air is found as follows: (partial pressure of water vapor/vapor pressure of water $) \times 100 .$ A sample of air at $21^{\circ} \mathrm{C}$ was cooled to $15^{\circ} \mathrm{C}$, where moisture began to condense as dew. What was the relative humidity of the air at $21^{\circ} \mathrm{C}$ ?

Lottie Adams

Numerade Educator

Problem 92

A sample of air at $21^{\circ} \mathrm{C}$ has a relative humidity of $58 \%$. At what temperature will water begin to condense as dew? (See Problem 11.91.)

Tianyu Li

Numerade Educator

Problem 93

The vapor pressure of benzene is $100.0 \mathrm{mmHg}$ at $26.1^{\circ} \mathrm{C}$ and $400.0 \mathrm{mmHg}$ at $60.6^{\circ} \mathrm{C}$. What is the boiling point of benzene at $760.0 \mathrm{mmHg}$ ?

Crystal Wang

Numerade Educator

Problem 94

The vapor pressure of water is $17.5 \mathrm{mmHg}$ at $20.0^{\circ} \mathrm{C}$ and $355.1 \mathrm{mmHg}$ at $80.0^{\circ} \mathrm{C}$. Calculate the boiling point of water at $760.0 \mathrm{mmHg}$.

Lottie Adams

Numerade Educator

Problem 95

Describe the behavior of carbon dioxide gas when compressed at the following temperatures:
a. $20^{\circ} \mathrm{C}$
b. $-70^{\circ} \mathrm{C}$
c. $40^{\circ} \mathrm{C}$
The triple point of carbon dioxide is $-57^{\circ} \mathrm{C}$ and $5.1 \mathrm{~atm}$, and the critical point is $31^{\circ} \mathrm{C}$ and 73 atm.

Natalie Johns

Numerade Educator

Problem 96

Describe the behavior of iodine vapor when cooled at the following pressures:
a. $120 \mathrm{~atm}$
b. $1 \mathrm{~atm}$
c. $50 \mathrm{mmHg}$
The triple point of iodine is $114^{\circ} \mathrm{C}$ and $90.1 \mathrm{~mm} \mathrm{Hg}$, and the critical point is $512^{\circ} \mathrm{C}$ and 116 atm.

Natalie Johns

Numerade Educator

Problem 97

Describe the formation of hydrogen bonds in propanol, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{OH}$. Represent possible hydrogen bonding structures in propanol by using structural formulas and the conventional notation for a hydrogen bond.

Natalie Johns

Numerade Educator

Problem 98

Describe the formation of hydrogen bonds in hydrogen peroxide, $\mathrm{H}_{2} \mathrm{O}_{2}$. Represent possible hydrogen bonding structures in hydrogen peroxide by using structural formulas and the conventional notation for a hydrogen bond.

Natalie Johns

Numerade Educator

Problem 99

Ethylene glycol $\left(\mathrm{CH}_{2} \mathrm{OHCH}_{2} \mathrm{OH}\right)$ is a slightly viscous liquid that boils at $198^{\circ} \mathrm{C}$. Pentane $\left(\mathrm{C}_{5} \mathrm{H}_{12}\right)$, which has approximately the same molecular weight as ethylene glycol, is a nonviscous liquid that boils at $36^{\circ} \mathrm{C}$. Explain the differences in physical characteristics of these two compounds.

Natalie Johns

Numerade Educator

Problem 100

Pentylamine, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}$, is a liquid
that boils at $104^{\circ} \mathrm{C}$ and has a viscosity of $10 \times 10^{-4} \mathrm{~kg} /(\mathrm{m} \cdot \mathrm{s})$
Triethylamine, $\left(\mathrm{CH}_{3} \mathrm{CH}_{2}\right)_{3} \mathrm{~N}$, is a liquid that boils at $89^{\circ} \mathrm{C}$ and has a viscosity of about $4 \times 10^{-4} \mathrm{~kg} /(\mathrm{m} \cdot \mathrm{s})$. Explain the differences in properties of these two compounds.

Crystal Wang

Numerade Educator

Problem 101

Consider the elements $\mathrm{Al}, \mathrm{Si}, \mathrm{P}$, and $\mathrm{S}$ from the third row of the periodic table. In each case, identify the type of solid the element would form.

Natalie Johns

Numerade Educator

Problem 102

The elements in Problem $11.101$ form the fluorides $\mathrm{AlF}_{3}, \mathrm{SiF}_{4}, \mathrm{PF}_{3}$, and $\mathrm{SF}_{4}$. In each case, identify the type of solid formed by the fluoride.

Tianyu Li

Numerade Educator

Problem 103

Decide which substance in each of the following pairs has the lower melting point. Explain how you made each choice.
a. potassium chloride, $\mathrm{KCl}$; or calcium oxide, $\mathrm{CaO}$

Natalie Johns

Numerade Educator

Problem 104

Decide which substance in each of the following pairs has the lower melting point. Explain how you made each choice.
a. magnesium oxide, $\mathrm{MgO} ;$ or hexane, $\mathrm{C}_{6} \mathrm{H}_{14}$
b. 1-propanol,
c. silicon, Si; or sodium, $\mathrm{Na}$
d. methane, $\mathrm{CH}_{4}$; or silane, $\mathrm{SiH}_{4}$

Natalie Johns

Numerade Educator

Problem 105

Iridium metal, Ir, crystallizes in a face-centered cubic (close-packed) structure. The edge length of the unit cell was found by $x$ -ray diffraction to be $383.9 \mathrm{pm}$. The density of iridium is $22.42 \mathrm{~g} / \mathrm{cm}^{3}$. Calculate the mass of an iridium atom. Use Avogadro's number to calculate the atomic weight of iridium.

Lottie Adams

Numerade Educator

Problem 106

The edge length of the unit cell of tantalum metal, $\mathrm{Ta}$, is $330.6 \mathrm{pm} ;$ the unit cell is body-centered cubic (one atom at each lattice point). Tantalum has a density of $16.69 \mathrm{~g} / \mathrm{cm}^{3}$. What is the mass of a tantalum atom? Use Avogadro's number to calculate the atomic weight of tantalum.

Tianyu Li

Numerade Educator

Problem 107

Use your answer to Problem $11.81$ to calculate the radius of the copper atom. Assume that copper atoms are spheres. Then note that the spheres on any face of a unit cell touch along the diagonal.

Tianyu Li

Numerade Educator

Problem 108

Rubidium metal has a body-centered cubic structure (with one atom at each lattice point). The density of the metal is $1.532 \mathrm{~g} / \mathrm{cm}^{3}$. From this information and the atomic weight, calculate the edge length of the unit cell. Now assume that rubidium atoms are spheres. Each corner sphere of the unit cell touches the body-centered sphere. Calculate the radius of a rubidium atom.

Lottie Adams

Numerade Educator

Problem 109

Calculate the percent of volume that is actually occupied by spheres in a body-centered cubic lattice of identical spheres. You can do this by first relating the radius of a sphere, $r$, to the length of an edge of a unit cell, $l$. (Note that the spheres do not touch along an edge, but do touch along a diagonal passing through the body-centered sphere.) Then calculate the volume of a unit cell in terms of $r .$ The volume occupied by spheres equals the number of spheres per unit cell times the volume of a sphere $\left(4 \pi r^{3} / 3\right)$.

Lottie Adams

Numerade Educator

Problem 110

Calculate the percent of volume that is actually occupied by spheres in a face-centered cubic lattice of identical spheres. You can do this by first relating the radius of a sphere, $r$, to the length of an edge of a unit cell, $l$. (Note that the spheres do not touch along an edge, but do touch along the diagonal of a face.) Then calculate the volume of a unit cell in terms of $r$. The volume occupied by spheres equals the number of spheres per unit cell times the volume of a sphere $\left(4 \pi r^{3} / 3\right)$.

Lottie Adams

Numerade Educator

Problem 111

For the hydrogen halides and the noble gases, we have the following boiling points:
$\begin{aligned}&\text { Halogen } & \text { Noble }\end{aligned}$ ${ }^{\circ} \mathbf{C}$ Family, Gases, ${ }^{\circ} \mathbf{C}$
1 $-246$ 19 HF, Ne, $-115$ Ar, $-186$ $\mathrm{HCl}$ $\mathrm{HBr}$ $-67$ $\mathrm{Kr},-152$
HI, $-35$ $\mathrm{Xe},-108$
Account for the following:
a. The general trend in the boiling points of the hydrides and the noble gases.
b. The unusual boiling point of hydrogen fluoride.
c. The observation that the hydrogen halides have boiling points that are significantly higher than the noble gases.

MB

Matthew Bigler

Numerade Educator

Problem 112

For the carbon and nitrogen family hydrides, we have the following boiling points:
Carbon $\quad$ Nitrogen Family, ${ }^{\circ} \mathbf{C} \quad$ Family, ${ }^{\circ} \mathbf{C}$
$\mathrm{CH}_{4},-164 \quad \mathrm{NH}_{3},-33$
$\mathrm{SiH}_{4},-112 \quad \mathrm{PH}_{3},-88$
$\begin{array}{ll}\mathrm{GeH}_{4},-88 & \mathrm{AsH}_{3},-55\end{array}$
$\mathrm{SnH}_{4},-52 \quad \mathrm{SbH}_{3},-17$
Account for the following:
a. The general trend in the boiling points of the binary hydrides.
b. The unusual boiling point of ammonia.
c. The observation that the nitrogen family hydrides have boiling points that are notably higher than those of the carbon family.

Tianyu Li

Numerade Educator

Problem 113

Account for the following observations:
a. Both diamond and silicon carbide are very hard, whereas graphite is both soft and slippery.
b. Carbon dioxide is a gas, whereas silicon dioxide is a highmelting solid.

Natalie Johns

Numerade Educator

Problem 114

Greater variation exists between the properties of the first and second members of a family in the periodic table than between other members. Discuss this observation for the oxygen family using the following data. $\begin{array}{llll} & \text { Boiling } & & \text { Boiling } \\ \text { Element } & \text { Point, }^{\circ} \mathbf{C} & \text { Compound } & \text { Point, }^{\circ} \mathbf{C} \\ \mathrm{O}_{2} & -183 & \mathrm{H}_{2} \mathrm{O} & 100 \\ \mathrm{~S}_{8} & 445 & \mathrm{H}_{2} \mathrm{~S} & -61 \\ \mathrm{Se}_{8} & 685 & \mathrm{H}_{2} \mathrm{Se} & -42\end{array}$

Tianyu Li

Numerade Educator

Problem 115

Use chemical principles to discuss the following observations:
a. $\mathrm{CO}_{2}$ sublimes at $-78^{\circ} \mathrm{C}$, whereas $\mathrm{SiO}_{2}$ boils at $2200^{\circ} \mathrm{C}$.
b. HF boils at $19^{\circ} \mathrm{C}$, whereas $\mathrm{HCl}$ boils at $-85^{\circ} \mathrm{C}$.
c. $\mathrm{CF}_{4}$ boils at $-128^{\circ} \mathrm{C}$, whereas $\mathrm{SiF}_{4}$ boils at $-86^{\circ} \mathrm{C}$.

Natalie Johns

Numerade Educator

Problem 116

a. Draw Lewis structures of each of the following compounds: $\mathrm{LiH}, \mathrm{NH}_{3}, \mathrm{CH}_{4}, \mathrm{CO}_{2}$
b. Which of these has the highest boiling point? Why?
c. Which of these has the lowest boiling point? Why?
d. Which of these has the next-to-highest boiling point? Why?

Natalie Johns

Numerade Educator

Problem 117

The vapor pressure of a volatile liquid can be determined by slowly bubbling a known volume of gas through the liquid at a given temperature and pressure. In an experiment, a 5.40-L sample of nitrogen gas, $\mathrm{N}_{2}$, at $20.0^{\circ} \mathrm{C}$ and $745 \mathrm{mmHg}$ is bubbled through liquid isopropyl alcohol, $\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}$, at $20.0^{\circ} \mathrm{C}$. Nitrogen containing the vapor of $\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}$ at its vapor pressure leaves the vessel at $20.0^{\circ} \mathrm{C}$ and $745 \mathrm{mmHg} .$ It is found that $0.6149 \mathrm{~g} \mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}$ has evaporated. How many moles of $\mathrm{N}_{2}$ are in the gas leaving the liquid? How many moles of alcohol are in this gaseous mixture? What is the mole fraction of alcohol vapor in the gaseous mixture? What is the partial pressure of the alcohol in the gaseous mixture? What is the vapor pressure of $\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}$ at $20.0^{\circ} \mathrm{C} ?$

Lottie Adams

Numerade Educator

Problem 118

In an experiment, a sample of $6.35 \mathrm{~L}$ of nitrogen at $25.0{ }^{\circ} \mathrm{C}$ and $768 \mathrm{mmHg}$ is bubbled through liquid acetone, $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}$. The gas plus vapor at its equilibrium partial pressure leaves the liquid at the same temperature and pressure. If $6.550 \mathrm{~g}$ of acetone has evaporated, what is the vapor pressure of acetone at $25.0^{\circ} \mathrm{C}$ ? See Problem 11.117.

Tianyu Li

Numerade Educator

Problem 119

How much heat is needed to vaporize $10.0 \mathrm{~mL}$ of liquid hydrogen cyanide, $\mathrm{HCN}$, at $25.0^{\circ} \mathrm{C} ?$ The density of the liquid is $0.687 \mathrm{~g} / \mathrm{mL}$. Use standard heats of formation, which are given in Appendix $\mathrm{C}$.

Lottie Adams

Numerade Educator

Problem 120

How much heat is needed to vaporize $20.0 \mathrm{~mL}$ of liquid methanol, $\mathrm{CH}_{3} \mathrm{OH}$, at $25.0^{\circ} \mathrm{C}$ ? The density of the liquid is $0.787 \mathrm{~g} / \mathrm{mL}$. Use standard heats of formation, which are given in Appendix C.

Lottie Adams

Numerade Educator

Problem 121

How much heat must be added to $12.5 \mathrm{~g}$ of solid white phosphorus, $\mathrm{P}_{4}$, at $25.0^{\circ} \mathrm{C}$ to give the liquid at its melting point, $44.1^{\circ} \mathrm{C}$ ? The heat capacity of solid white phosphorus is $95.4 \mathrm{~J} /(\mathrm{K} \cdot \mathrm{mol})$; its heat of fusion is $2.63 \mathrm{~kJ} / \mathrm{mol}$.

Crystal Wang

Numerade Educator

Problem 122

How much heat must be added to $25.0 \mathrm{~g}$ of solid sodium, $\mathrm{Na}$, at $25.0^{\circ} \mathrm{C}$ to give the liquid at its melting point, $97.8^{\circ} \mathrm{C}$ ? The heat capacity of solid sodium is $28.2 \mathrm{~J} /(\mathrm{K} \cdot \mathrm{mol})$, and its heat of fusion is $2.60 \mathrm{~kJ} / \mathrm{mol}$.

Lottie Adams

Numerade Educator

Problem 123

Acetic acid, $\mathrm{CH}_{3} \mathrm{COOH}$, forms stable pairs of molecules held together by two hydrogen bonds.
Such molecules - themselves formed by the association of two simpler molecules-are called dimers. The vapor over liquid acetic acid consists of a mixture of monomers (single acetic acid molecules) and dimers. At $100.6^{\circ} \mathrm{C}$ the total pressure of vapor over liquid acetic acid is $436 \mathrm{mmHg}$. If the vapor consists of $0.630$ mole fraction of the dimer, what are the masses of monomer and dimer in $1.000 \mathrm{~L}$ of the vapor? What is the density of the vapor?

Lottie Adams

Numerade Educator

Problem 124

The total pressure of vapor over liquid acetic acid at $71.3^{\circ} \mathrm{C}$ is $146 \mathrm{mmHg}$. If the density of the vapor is $0.702 \mathrm{~g} / \mathrm{L}$
what is the mole fraction of dimer in the vapor? See Problem $11.123 .$

Taimoor Shabbir

Taimoor Shabbir

Numerade Educator