Chemistry An Atoms First Approach

Steven S. Zumdahl, Susan A. Zumdahl

Chapter 9

Liquids and Solids - all with Video Answers

Educators

MB

Chapter Questions

Problem 1

It is possible to balance a paper clip on the surface of water in a beaker. If you add a bit of soap to the water, however, the paper clip sinks. Explain how the paper clip can float and why it sinks when soap is added.

MB

Marisa Bellino

Numerade Educator

Problem 2

Consider a sealed container half-filled with water. Which statement best describes what occurs in the container?
a. Water evaporates until the air is saturated with water vapor; at this point, no more water evaporates.
b. Water evaporates until the air is overly saturated (supersaturated) with water, and most of this water recondenses; this cycle continues until a certain amount of water vapor is present, and then the cycle ceases.
c. Water does not evaporate because the container is sealed.
d. Water evaporates, and then water evaporates and recondenses simultaneously and continuously.
e. Water evaporates until it is eventually all in vapor form. Explain each choice. Justify your choice, and for choices you did not pick, explain what is wrong with them.

Kevin Zaborsky

Numerade Educator

Problem 3

Explain the following: You add $100 \mathrm{mL}$ water to a $500-\mathrm{mL}$ round-bottom flask and heat the water until it is boiling. You remove the heat and stopper the flask, and the boiling stops. You then run cool water over the neck of the flask, and the boiling begins again. It seems as though you are boiling water by cooling it.

MB

Marisa Bellino

Numerade Educator

Problem 4

Is it possible for the dispersion forces in a particular substance to be stronger than the hydrogen bonding forces in another substance? Explain your answer.

Kevin Zaborsky

Numerade Educator

Problem 5

Does the nature of intermolecular forces change when a substance goes from a solid to a liquid, or from a liquid to a gas? What causes a substance to undergo a phase change?

MB

Marisa Bellino

Numerade Educator

Problem 6

Why do liquids have a vapor pressure? Do all liquids have vapor pressures? Explain. Do solids exhibit vapor pressure? Explain. How does vapor pressure change with changing temperature? Explain.

Kevin Zaborsky

Numerade Educator

Problem 7

Water in an open beaker evaporates over time. As the water is evaporating, is the vapor pressure increasing, decreasing, or staying the same? Why?

MB

Marisa Bellino

Numerade Educator

Problem 8

What is the vapor pressure of water at $100^{\circ} \mathrm{C} ?$ How do you know?

Kevin Zaborsky

Numerade Educator

Problem 9

Refer to Fig. $9-41 .$ Why doesn't temperature increase continuously over time? That is, why does the temperature stay constant for periods of time?

MB

Marisa Bellino

Numerade Educator

Problem 10

Which are stronger, intermolecular or intramolecular forces for a given molecule? What observation(s) have you made that support this? Explain.

Kevin Zaborsky

Numerade Educator

Problem 11

Why does water evaporate?

MB

Marisa Bellino

Numerade Educator

Problem 12

Rationalize why chalk (calcium carbonate) has a higher melting point than motor oil (large compound made from carbon and hydrogen), which has a higher melting point than water and engages in relatively strong hydrogen bonding interactions.

Kevin Zaborsky

Numerade Educator

Problem 13

In the diagram below, which lines represent the hydrogen bonding? (FIGURE CAN'T COPY)
a. the dotted lines between the hydrogen atoms of one water molecule and the oxygen atoms of a different water molecule
b. the solid lines between a hydrogen atom and oxygen atom in the same water molecule
c. Both the solid lines and dotted lines represent hydrogen bonding.
d. There are no hydrogen bonds represented in the diagram.

MB

Marisa Bellino

Numerade Educator

Problem 14

Hydrogen bonding is a special case of very strong dipoledipole interactions possible among only certain atoms. What atoms in addition to hydrogen are necessary for hydrogen bonding? How does the small size of the hydrogen atom contribute to the unusual strength of the dipole-dipole forces involved in hydrogen bonding?

Kevin Zaborsky

Numerade Educator

Problem 15

Atoms are assumed to touch in closest packed structures, yet every closest packed unit cell contains a significant amount of empty space. Why?

MB

Marisa Bellino

Numerade Educator

Problem 16

Define critical temperature and critical pressure. In terms of the kinetic molecular theory, why is it impossible for a substance to exist as a liquid above its critical temperature?

Kevin Zaborsky

Numerade Educator

Problem 17

Use the kinetic molecular theory to explain why a liquid gets cooler as it evaporates from an insulated container.

MB

Marisa Bellino

Numerade Educator

Problem 18

Will a crystalline solid or an amorphous solid give a simpler X-ray diffraction pattern? Why?

Kevin Zaborsky

Numerade Educator

Problem 19

What is an alloy? Explain the differences in structure between substitutional and interstitial alloys. Give an example of each type.

MB

Marisa Bellino

Numerade Educator

Problem 20

Describe what is meant by a dynamic equilibrium in terms of the vapor pressure of a liquid.

Kevin Zaborsky

Numerade Educator

Problem 21

How does each of the following affect the rate of evaporation of a liquid in an open dish?
a. intermolecular forces
b. temperature
c. surface area

MB

Marisa Bellino

Numerade Educator

Problem 22

A common response to hearing that the temperature in New Mexico is $105^{\circ} \mathrm{F}$ is, "It's not that bad; it's a dry heat," whereas at the same time the summers in Atlanta, Georgia, are characterized as "dreadful," even though the air temperature is typically lower. What role does humidity play in how our bodies regulate temperature?

Kevin Zaborsky

Numerade Educator

Problem 23

When a person has a severe fever, one therapy used to reduce the fever is an "alcohol rub" Explain how the evaporation of alcohol from a person's skin removes heat energy from the body.

MB

Marisa Bellino

Numerade Educator

Problem 24

Why is a burn from steam typically much more severe than a burn from boiling water?

Kevin Zaborsky

Numerade Educator

Problem 25

When wet laundry is hung on a clothesline on a cold winter day, it will freeze but eventually dry. Explain.

MB

Marisa Bellino

Numerade Educator

Problem 26

Cake mixes and other packaged foods that require cooking often contain special directions for use at high elevations. Typically these directions indicate that the food should be cooked longer above 5000 ft. Explain why it takes longer to cook something at higher elevations.

Kevin Zaborsky

Numerade Educator

Problem 27

You have three covalent compounds with three very different boiling points. All of the compounds have similar molar mass and relative shape. Explain how these three compounds could have very different boiling points.

MB

Marisa Bellino

Numerade Educator

Problem 28

Compare and contrast the structures of the following solids.
a. diamond versus graphite
b. silica versus silicates versus glass

Kevin Zaborsky

Numerade Educator

Problem 29

Compare and contrast the structures of the following solids.
a. $\mathrm{CO}_{2}(s)$ versus $\mathrm{H}_{2} \mathrm{O}(s)$
b. $\mathrm{NaCl}(s)$ versus $\mathrm{CsCl}(s) ;$ see Exercise 69 for the structures.

Thomas Harr

Numerade Educator

Problem 30

Silicon carbide $(\mathrm{SiC})$ is an extremely hard substance that acts as an electrical insulator. Propose a structure for SiC.

Hailey Tomashek

Hailey Tomashek

Numerade Educator

Problem 31

How could you tell experimentally if $\operatorname{Ti} \mathrm{O}_{2}$ is an ionic solid or a network solid?

MB

Marisa Bellino

Numerade Educator

Problem 32

A common prank on college campuses is to switch the salt and sugar on dining hall tables, which is usually easy because the substances look so much alike. Yet, despite the similarity in their appearance, these two substances differ greatly in their properties, since one is a molecular solid and the other is an ionic solid. How do the properties differ and why?

Kevin Zaborsky

Numerade Educator

Problem 33

A plot of $\ln \left(P_{\text {vap }}\right)$ versus $1 / T(\mathrm{K})$ is linear with a negative slope. Why is this the case?

MB

Marisa Bellino

Numerade Educator

Problem 34

Iodine, like most substances, exhibits only three phases: solid, liquid, and vapor. The triple point of iodine is at 90 torr and $115^{\circ} \mathrm{C} .$ Which of the following statements concerning liquid $\mathrm{I}_{2}$ must be true? Explain your answer.
a. $\mathrm{I}_{2}(l)$ is more dense than $\mathrm{I}_{2}(g).$
b. $\mathrm{I}_{2}(l)$ cannot exist above $115^{\circ} \mathrm{C}.$
c. $\mathrm{I}_{2}(l)$ cannot exist at 1 atmosphere pressure.
d. $\mathrm{I}_{2}(l)$ cannot have a vapor pressure greater than 90 torr.
e. $\mathrm{I}_{2}(l)$ cannot exist at a pressure of 10 torr.

Kevin Zaborsky

Numerade Educator

Problem 35

Identify the most important types of interparticle forces present in the solids of each of the following substances.
a. $\mathrm{Ar}$
b. HCI
c. HF
d. $\mathrm{CaCl}_{2}$
$\mathbf{e} . \mathrm{CH}_{4}$
f. co
g. $\mathrm{NaNO}_{3}$

MB

Marisa Bellino

Numerade Educator

Problem 36

Identify the most important types of interparticle forces present in the solids of each of the following substances.
a. $\mathrm{BaSO}_{4}$
b. $\mathrm{H}_{2} \mathrm{S}$
c. Xe
d. $C_{2} H_{6}$
$$\begin{array}{l}
\text { e. } \mathrm{CsI} \\
\text { f. } \mathrm{P}_{4} \\
\text { g. } \mathrm{NH}_{3}
\end{array}$$

Kevin Zaborsky

Numerade Educator

Problem 37

Predict which substance in each of the following pairs would have the greater intermolecular forces.
a. $\mathrm{CO}_{2}$ or $\mathrm{OCS}$
b. $\operatorname{SeO}_{2}$ or $\mathrm{SO}_{2}$
$\mathbf{c .} \cdot \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}$ or $\mathrm{H}_{2} \mathrm{NCH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}$
d. $\mathrm{CH}_{3} \mathrm{CH}_{3}$ or $\mathrm{H}_{2} \mathrm{CO}$
e. $\mathrm{CH}_{3} \mathrm{OH}$ or $\mathrm{H}_{2} \mathrm{CO}$

MB

Marisa Bellino

Numerade Educator

Problem 38

Consider the compounds $\mathrm{Cl}_{2}, \mathrm{HCl}, \mathrm{F}_{2}, \mathrm{NaF},$ and $\mathrm{HF}$. Which compound has a boiling point closest to that of argon? Explain.

Kevin Zaborsky

Numerade Educator

Problem 39

Rationalize the difference in boiling points for each of the following pairs of substances:
(EQUATION CAN'T COPY)

MB

Marisa Bellino

Numerade Educator

Problem 40

Consider the following electrostatic potential diagrams: (FIGURE CAN'T COPY) Rank the compounds from lowest to highest boiling point and explain your answer.

Kevin Zaborsky

Numerade Educator

Problem 41

In each of the following groups of substances, pick the one that has the given property. Justify your answer.
a. highest boiling point: HBr, $\mathrm{Kr},$ or $\mathrm{Cl}_{2}$
b. highest freezing point: $\mathrm{H}_{2} \mathrm{O}, \mathrm{NaCl},$ or $\mathrm{HF}$
c. lowest vapor pressure at $25^{\circ} \mathrm{C}: \mathrm{Cl}_{2}, \mathrm{Br}_{2},$ or $\mathrm{I}_{2}$
d. lowest freezing point: $\mathrm{N}_{2}, \mathrm{CO},$ or $\mathrm{CO}_{2}$
e. lowest boiling point: $\mathrm{CH}_{4}, \mathrm{CH}_{3} \mathrm{CH}_{3},$ or $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}$
f. highest boiling point: HF, HCl, or HBr
g.(EQUATION CAN'T COPY)

MB

Marisa Bellino

Numerade Educator

Problem 42

In each of the following groups of substances, pick the one that has the given property. Justify each answer.
a. highest boiling point: $\mathrm{CCl}_{4}, \mathrm{CF}_{4}, \mathrm{CBr}_{4}$
b. lowest freezing point: $\mathrm{LiF}, \mathrm{F}_{2}, \mathrm{HCl}$
c. smallest vapor pressure at $25^{\circ} \mathrm{C}: \mathrm{CH}_{3} \mathrm{OCH}_{3}, \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$ $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}$
d. greatest viscosity: $\mathrm{H}_{2} \mathrm{S}, \mathrm{HF}, \mathrm{H}_{2} \mathrm{O}_{2}$
e. greatest heat of vaporization: $\mathrm{H}_{2} \mathrm{CO}, \mathrm{CH}_{3} \mathrm{CH}_{3}, \mathrm{CH}_{4}$
f. smallest enthalpy of fusion: $\mathrm{I}_{2}, \mathrm{CsBr}, \mathrm{CaO}$

Kevin Zaborsky

Numerade Educator

Problem 43

The shape of the meniscus of water in a glass tube is different from that of mercury in a glass tube. Why? (FIGURE CAN'T COPY)

MB

Marisa Bellino

Numerade Educator

Problem 44

Explain why water forms into beads on a waxed car finish.

Kevin Zaborsky

Numerade Educator

Problem 45

Hydrogen peroxide $\left(\mathrm{H}_{2} \mathrm{O}_{2}\right)$ is a syrupy liquid with a relatively low vapor pressure and a normal boiling point of $152.2^{\circ} \mathrm{C}$. Rationalize the differences of these physical properties from those of water.

MB

Marisa Bellino

Numerade Educator

Problem 46

Carbon diselenide $\left(\mathrm{CSe}_{2}\right)$ is a liquid at room temperature. The normal boiling point is $125^{\circ} \mathrm{C},$ and the melting point is $-45.5^{\circ} \mathrm{C} .$ Carbon disulfide $\left(\mathrm{CS}_{2}\right)$ is also a liquid at room temperature with normal boiling and melting points of $46.5^{\circ} \mathrm{C}$ and $-111.6^{\circ} \mathrm{C},$ respectively. How do the strengths of the intermolecular forces vary from $\mathrm{CO}_{2}$ to $\mathrm{CS}_{2}$ to $\mathrm{CSe}_{2}$ ? Explain.

Kevin Zaborsky

Numerade Educator

Problem 47

X rays from a copper X-ray tube $(\lambda=154 \mathrm{pm})$ were diffracted at an angle of 14.22 degrees by a crystal of silicon. Assuming first-order diffraction $(n=1$ in the Bragg equation), what is the interplanar spacing in silicon?

MB

Marisa Bellino

Numerade Educator

Problem 48

The second-order diffraction $(n=2)$ for a gold crystal is at an angle of $22.20^{\circ}$ for $\mathrm{X}$ rays of $154 \mathrm{pm}$. What is the spacing between these crystal planes?

Kevin Zaborsky

Numerade Educator

Problem 49

A topaz crystal has an interplanar spacing $(d)$ of $1.36 Å$ $\left(1Å =1 \times 10^{-10} \mathrm{m}\right) .$ Calculate the wavelength of the X ray that should be used if $\theta=15.0^{\circ}$ (assume $n=1$ ).

MB

Marisa Bellino

Numerade Educator

Problem 50

X rays of wavelength 2.63 Å were used to analyze a crystal. The angle of first-order diffraction $(n=1$ in the Bragg equation) was 15.55 degrees. What is the spacing between crystal planes, and what would be the angle for second-order diffraction $(n=2) ?$

Kevin Zaborsky

Numerade Educator

Problem 51

Calcium has a cubic closest packed structure as a solid. Assuming that calcium has an atomic radius of $197 \mathrm{pm},$ calculate the density of solid calcium.

MB

Marisa Bellino

Numerade Educator

Problem 52

Nickel has a face-centered cubic unit cell. The density of nickel is $6.84 \mathrm{g} / \mathrm{cm}^{3} .$ Calculate a value for the atomic radius of nickel.

Kevin Zaborsky

Numerade Educator

Problem 53

A certain form of lead has a cubic closest packed structure with an edge length of $492 \mathrm{pm} .$ Calculate the value of the atomic radius and the density of lead.

MB

Marisa Bellino

Numerade Educator

Problem 54

Iridium (Ir) has a face-centered cubic unit cell with an edge length of $383.3 \mathrm{pm} .$ Calculate the density of solid iridium.

Kevin Zaborsky

Numerade Educator

Problem 55

You are given a small bar of an unknown metal X. You find the density of the metal to be $10.5 \mathrm{g} / \mathrm{cm}^{3} .$ An X-ray diffraction experiment measures the edge of the face-centered cubic unit cell as $4.09 Å\left(1 Å=10^{-10} \mathrm{m}\right) .$ Identify X.

MB

Marisa Bellino

Numerade Educator

Problem 56

A metallic solid with atoms in a face-centered cubic unit cell with an edge length of $392 \mathrm{pm}$ has a density of $21.45 \mathrm{g} / \mathrm{cm}^{3}$ Calculate the atomic mass and the atomic radius of the metal. Identify the metal.

Kevin Zaborsky

Numerade Educator

Problem 57

Titanium metal has a body-centered cubic unit cell. The density of titanium is $4.50 \mathrm{g} / \mathrm{cm}^{3} .$ Calculate the edge length of the unit cell and a value for the atomic radius of titanium. (Hint: In a body-centered arrangement of spheres, the spheres touch across the body diagonal.)

Madi Sousa

Numerade Educator

Problem 58

Barium has a body-centered cubic structure. If the atomic radius of barium is $222 \mathrm{pm},$ calculate the density of solid barium.

Kevin Zaborsky

Numerade Educator

Problem 59

The radius of gold is $144 \mathrm{pm},$ and the density is $19.32 \mathrm{g} / \mathrm{cm}^{3}$ Does elemental gold have a face-centered cubic structure or a body-centered cubic structure?

MB

Marisa Bellino

Numerade Educator

Problem 60

The radius of tungsten is $137 \mathrm{pm}$ and the density is $19.3 \mathrm{g} / \mathrm{cm}^{3}$. Does elemental tungsten have a face-centered cubic structure or a body-centered cubic structure?

Kevin Zaborsky

Numerade Educator

Problem 61

What fraction of the total volume of a cubic closest packed structure is occupied by atoms? (Hint: $V_{\text {sphere }}=\frac{4}{3} \pi r^{3} .$ ) What fraction of the total volume of a simple cubic structure is occupied by atoms? Compare the answers.

David Collins

Numerade Educator

Problem 62

Iron has a density of $7.86 \mathrm{g} / \mathrm{cm}^{3}$ and crystallizes in a bodycentered cubic lattice. Show that only $68 \%$ of a body-centered lattice is actually occupied by atoms, and determine the atomic radius of iron.

Kevin Zaborsky

Numerade Educator

Problem 63

Explain how doping silicon with either phosphorus or gallium increases the electrical conductivity over that of pure silicon.

Kathleen Kozinski

Kathleen Kozinski

Numerade Educator

Problem 64

Explain how a p-n junction makes an excellent rectifier.

Kevin Zaborsky

Numerade Educator

Problem 65

Selenium is a semiconductor used in photocopying machines. What type of semiconductor would be formed if a small amount of indium impurity is added to pure selenium?

Thomas Harr

Numerade Educator

Problem 66

The Group 3 A/Group 5 A semiconductors are composed of equal amounts of atoms from Group $3 \mathrm{A}$ and Group $5 \mathrm{A}-$ for example, InP and GaAs. These types of semiconductors are used in light-emitting diodes and solid-state lasers. What would you add to make a p-type semiconductor from pure GaAs? How would you dope pure GaAs to make an n-type semiconductor?

Matthew Confer

Numerade Educator

Problem 67

The band gap in aluminum phosphide (AIP) is 2.5 electronvolts $\left(1 \mathrm{eV}=1.6 \times 10^{-19} \mathrm{J}\right) .$ What wavelength of light is emitted by an AlP diode?

MB

Marisa Bellino

Numerade Educator

Problem 68

An aluminum antimonide solid-state laser emits light with a wavelength of $730 . \mathrm{nm} .$ Calculate the band gap in joules.

Kevin Zaborsky

Numerade Educator

Problem 69

The structures of some common crystalline substances are shown below. Show that the net composition of each unit cell corresponds to the correct formula of each substance.

Madi Sousa

Numerade Educator

Problem 70

The unit cell for nickel arsenide is shown below. What is the formula of this compound? (FIGURE CAN'T COPY)

Kevin Zaborsky

Numerade Educator

Problem 71

Cobalt fluoride crystallizes in a closest packed array of fluoride ions with the cobalt ions filling one-half of the octahedral holes. What is the formula of this compound?

Madi Sousa

Numerade Educator

Problem 72

The compounds $\mathrm{Na}_{2} \mathrm{O},$ CdS, and $\mathrm{ZrI}_{4}$ all can be described as cubic closest packed anions with the cations in tetrahedral holes. What fraction of the tetrahedral holes is occupied for each case?

Kevin Zaborsky

Numerade Educator

Problem 73

What is the formula for the compound that crystallizes with a cubic closest packed array of sulfur ions, and that contains zinc ions in $\frac{1}{8}$ of the tetrahedral holes and aluminum ions in $\frac{1}{2}$ of the octahedral holes?

Madi Sousa

Numerade Educator

Problem 74

Assume the two-dimensional structure of an ionic compound, $\mathbf{M}_{x} \mathbf{A}_{y},$ is (FIGURE CAN'T COPY)What is the empirical formula of this ionic compound?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 75

A certain metal fluoride crystallizes in such a way that the fluoride ions occupy simple cubic lattice sites, while the metal ions occupy the body centers of half the cubes. What is the formula of the metal fluoride?

Madi Sousa

Numerade Educator

Problem 76

The structure of manganese fluoride can be described as a simple cubic array of manganese ions with fluoride ions at the center of each edge of the cubic unit cell. What is the charge of the manganese ions in this compound?

Kevin Zaborsky

Numerade Educator

Problem 77

The unit cell of MgO is shown below. (FIGURE CAN'T COPY) Does MgO have a structure like that of NaCl or ZnS? If the density of $\mathrm{MgO}$ is $3.58 \mathrm{g} / \mathrm{cm}^{3},$ estimate the radius (in centimeters) of the $\mathrm{O}^{2-}$ anions and the $\mathrm{Mg}^{2+}$ cations.

Shazia Naz

Numerade Educator

Problem 78

In solid KCl the smallest distance between the centers of a potassium ion and a chloride ion is $314 \mathrm{pm} .$ Calculate the length of the edge of the unit cell and the density of KCl, assuming it has the same structure as sodium chloride.

Kevin Zaborsky

Numerade Educator

Problem 79

The CsCl structure is a simple cubic array of chloride ions with a cesium ion at the center of each cubic array (see Exercise 69 ). Given that the density of cesium chloride is $3.97 \mathrm{g} / \mathrm{cm}^{3},$ and assuming that the chloride and cesium ions touch along the body diagonal of the cubic unit cell, calculate the distance between the centers of adjacent $\mathrm{Cs}^{+}$ and $\mathrm{Cl}^{-}$ ions in the solid. Compare this value with the expected distance based on the sizes of the ions. The ionic radius of $\mathrm{Cs}^{+}$ is $169 \mathrm{pm},$ and the ionic radius of $\mathrm{Cl}^{-}$ is $181 \mathrm{pm}$.

Madi Sousa

Numerade Educator

Problem 80

MnO has either the NaCl type structure or the CsCl type structure (see Exercise 69 ). The edge length of the MnO unit cell is $4.47 \times 10^{-8} \mathrm{cm}$ and the density of $\mathrm{MnO}$ is $5.28 \mathrm{g} / \mathrm{cm}^{3}$
a. Does MnO crystallize in the NaCl or the CsCl type structure?
b. Assuming that the ionic radius of oxygen is $140 . \mathrm{pm},$ estimate the ionic radius of manganese.

Kevin Zaborsky

Numerade Educator

Problem 81

What type of solid will each of the following substances form?
a. $\mathrm{CO}_{2}$
b. $\mathrm{SiO}_{2}$
c. $\mathrm{Si}$
d. $\mathrm{CH}_{4}$
e. $\mathbf{R} \mathbf{u}$
f. $\mathrm{I}_{2}$

MB

Marisa Bellino

Numerade Educator

Problem 82

What type of solid will each of the following substances form?
a. $\mathrm{diamond}$
b. $\mathrm{PH}_{3}$
c. $\mathrm{H}_{2}$
d. $\mathrm{Mg}$
e. $\mathrm{KCl}$
f. quartz
g. $\mathrm{NH}_{4} \mathrm{NO}_{3}$
h. $\mathrm{SF}_{2}$
i. $\mathrm{Ar}$
j. $\mathrm{Cu}$
k. $\mathrm{C}_{6} \mathbf{H}_{12} \mathbf{O}_{6}$

Kevin Zaborsky

Numerade Educator

Problem 83

The memory metal, nitinol, is an alloy of nickel and titanium. It is called a memory metal because after being deformed, a piece of nitinol wire will return to its original shape. The structure of nitinol consists of a simple cubic array of Ni atoms and an inner penetrating simple cubic array of Ti atoms. In the extended lattice, a Ti atom is found at the center of a cube of Ni atoms; the reverse is also true.
a. Describe the unit cell for nitinol.
b. What is the empirical formula of nitinol?
c. What are the coordination numbers (number of nearest neighbors) of Ni and Ti in nitinol?

Madi Sousa

Numerade Educator

Problem 84

Superalloys have been made of nickel and aluminum. The alloy owes its strength to the formation of an ordered phase, called the gamma-prime phase, in which Al atoms are at the corners of a cubic unit cell and Ni atoms are at the face centers. What is the composition (relative numbers of atoms) for this phase of the nickel-aluminum superalloy?

Kevin Zaborsky

Numerade Educator

Problem 85

Perovskite is a mineral containing calcium, titanium, and oxygen. Two different representations of the unit cell are shown below. Show that both these representations give the same formula and the same number of oxygen atoms around each titanium atom.

Madi Sousa

Numerade Educator

Problem 86

A mineral crystallizes in a cubic closest packed array of oxygen ions with aluminum ions in some of the octahedral holes and magnesium ions in some of the tetrahedral holes. Deduce the formula of this mineral and predict the fraction of octahedral holes and tetrahedral holes that are filled by the various cations.

Dr. Satish Ingale

Dr. Satish Ingale

Numerade Educator

Problem 87

Materials containing the elements Y, Ba, Cu, and O that are superconductors (electrical resistance equals zero) at temperatures above that of liquid nitrogen were recently discovered. The structures of these materials are based on the perovskite structure. Were they to have the ideal perovskite structure, the superconductor would have the structure shown in part (a) of the following figure.
a. What is the formula of this ideal perovskite material?
b. How is this structure related to the perovskite structure shown in Exercise $85 ?$
These materials, however, do not act as superconductors unless they are deficient in oxygen. The structure of the actual superconducting phase appears to be that shown in part (b) of the figure.
c. What is the formula of this material?

Madi Sousa

Numerade Educator

Problem 88

The structures of another class of ceramic, high-temperature superconductors are shown in figures a-d.
a. Determine the formula of each of these four superconductors.
b. One of the structural features that appears to be essential for high-temperature superconductivity is the presence of planar sheets of copper and oxygen atoms. As the number of sheets in each unit cell increases, the temperature for the onset of superconductivity increases. Order the four structures from lowest to the highest superconducting temperature.
c. Assign oxidation states to Cu in each structure assuming Tl exists as $\mathrm{Tl}^{3+} .$ The oxidation states of $\mathrm{Ca}, \mathrm{Ba},$ and $\mathrm{O}$ are assumed to be $+2,+2,$ and $-2,$ respectively.
d. It also appears that copper must display a mixture of oxidation states for a material to exhibit superconductivity. Explain how this occurs in these materials as well as in the superconductor in Exercise 87.
(FIGURE CAN'T COPY)

Kevin Zaborsky

Numerade Educator

Problem 89

Plot the following data and determine $\Delta H_{\text {vap }}$ for magnesium and lithium. In which metal is the bonding stronger?
(TABLE CAN'T COPY)

David Collins

Numerade Educator

Problem 90

From the following data for liquid nitric acid, determine its heat of vaporization and normal boiling point. (TABLE CAN'T COPY)

Kevin Zaborsky

Numerade Educator

Problem 91

In Breckenridge, Colorado, the typical atmospheric pressure is $520 .$ torr. What is the boiling point of water $\left(\Delta H_{\mathrm{vap}}=\right.$
$40.7 \mathrm{kJ} / \mathrm{mol}$ in Breckenridge?

Madi Sousa

Numerade Educator

Problem 92

The temperature inside a pressure cooker is $115^{\circ} \mathrm{C}$. Calculate the vapor pressure of water inside the pressure cooker. What would be the temperature inside the pressure cooker if the vapor pressure of water was 3.50 atm?

Kevin Zaborsky

Numerade Educator

Problem 93

Carbon tetrachloride, $\mathrm{CCl}_{4},$ has a vapor pressure of 213 torr at $40 .^{\circ} \mathrm{C}$ and 836 torr at $80 .^{\circ} \mathrm{C} .$ What is the normal boiling point of $\mathrm{CCl}_{4} ?$

Matthew Confer

Numerade Educator

Problem 94

Diethyl ether $\left(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OCH}_{2} \mathrm{CH}_{3}\right)$ was one of the first chemicals used as an anesthetic. At $34.6^{\circ} \mathrm{C},$ diethyl ether has a vapor pressure of $760 .$ torr, and at $17.9^{\circ} \mathrm{C},$ it has a vapor pressure of $400 .$ torr. What is the $\Delta H$ of vaporization for diethyl ether?

Kevin Zaborsky

Numerade Educator

Problem 95

A substance, $\mathrm{X}$, has the following properties: (TABLE CAN'T COPY) Sketch a heating curve for substance $X$ starting at $-50 .^{\circ} \mathrm{C}$.

Shazia Naz

Numerade Educator

Problem 96

Use the heating-cooling curve below to answer the following questions. (TABLE CAN'T COPY)
a. What is the freezing point of the liquid?
b. What is the boiling point of the liquid?
c. Which is greater, the heat of fusion or the heat of vaporization? Explain each term and explain how the heatingcooling curve above helps you to answer the question.

Kevin Zaborsky

Numerade Educator

Problem 97

The molar heat of fusion of sodium metal is $2.60 \mathrm{kJ} / \mathrm{mol}$, whereas its heat of vaporization is $97.0 \mathrm{kJ} / \mathrm{mol}$.
a. Why is the heat of vaporization so much larger than the heat of fusion?
b. What quantity of heat would be needed to melt $1.00 \mathrm{g}$ sodium at its normal melting point?
c. What quantity of heat would be needed to vaporize $1.00 \mathrm{g}$ sodium at its normal boiling point?
d. What quantity of heat would be evolved if 1.00 g sodium vapor condensed at its normal boiling point?

Madi Sousa

Numerade Educator

Problem 98

The molar heat of fusion of benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ is $9.92 \mathrm{kJ} / \mathrm{mol}$. Its molar heat of vaporization is $30.7 \mathrm{kJ} / \mathrm{mol}$. Calculate the heat required to melt 8.25 g benzene at its normal melting point. Calculate the heat required to vaporize 8.25 g benzene at its normal boiling point. Why is the heat of vaporization more than three times the heat of fusion?

Kevin Zaborsky

Numerade Educator

Problem 99

What quantity of energy does it take to convert 0.500 kg ice at $-20 .^{\circ} \mathrm{C}$ to steam at $250 .^{\circ} \mathrm{C} ?$ Specific heat capacities: ice, $2.03 \mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C} ;$ liquid, $4.2 \mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C} ;$ steam, $2.0 \mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C} ; \Delta H_{\mathrm{vap}}=$ $40.7 \mathrm{kJ} / \mathrm{mol} ; \Delta H_{\mathrm{fus}}=6.02 \mathrm{kJ} / \mathrm{mol}.$

MB

Marisa Bellino

Numerade Educator

Problem 100

Consider a 75.0 -g sample of $\mathrm{H}_{2} \mathrm{O}(g)$ at $125^{\circ} \mathrm{C}$. What phase or phases are present when $215 \mathrm{kJ}$ of energy is removed from this sample? (See Exercise 99.)

Kevin Zaborsky

Numerade Educator

Problem 101

An ice cube tray contains enough water at $22.0^{\circ} \mathrm{C}$ to make 18 ice cubes that each has a mass of $30.0 \mathrm{g}$. The tray is placed in a freezer that uses $\mathrm{CF}_{2} \mathrm{Cl}_{2}$ as a refrigerant. The heat of vaporization of $\mathrm{CF}_{2} \mathrm{Cl}_{2}$ is $158 \mathrm{J} / \mathrm{g} .$ What mass of $\mathrm{CF}_{2} \mathrm{Cl}_{2}$ must be vaporized in the refrigeration cycle to convert all the water at $22.0^{\circ} \mathrm{C}$ to ice at $-5.0^{\circ} \mathrm{C} ?$ The heat capacities for $\mathrm{H}_{2} \mathrm{O}(s)$ and $\mathrm{H}_{2} \mathrm{O}(l)$ are $2.03 \mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C}$ and $4.18 \mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C},$ respectively, and the
enthalpy of fusion for ice is $6.02 \mathrm{kJ} / \mathrm{mol}$.

MB

Marisa Bellino

Numerade Educator

Problem 102

A $0.250-g$ chunk of sodium metal is cautiously dropped into a mixture of $50.0 \mathrm{g}$ water and $50.0 \mathrm{g}$ ice, both at $0^{\circ} \mathrm{C}$. The reaction is $$2 \mathrm{Na}(s)+2 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow 2 \mathrm{NaOH}(a q)+\mathrm{H}_{2}(g) \quad \Delta H=-368 \mathrm{kJ}$$ Assuming no heat loss to the surroundings, will the ice melt? Assuming the final mixture has a specific heat capacity of
$4.18 \mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C},$ calculate the final temperature. The enthalpy of fusion for ice is $6.02 \mathrm{kJ} / \mathrm{mol}$.

Kevin Zaborsky

Numerade Educator

Problem 103

Consider the phase diagram given below. What phases are present at points $A$ through $H$ ? Identify the triple point, normal boiling point, normal freezing point, and critical point. Which phase is denser, solid or liquid? (GRAPH CAN'T COPY)

Thomas Harr

Numerade Educator

Problem 104

Sulfur exhibits two solid phases, rhombic and monoclinic. Use the accompanying phase diagram for sulfur to answer the following questions. (The phase diagram is not to scale.) (GRAPH CAN'T COPY)
a. How many triple points are in the phase diagram?
b. What phases are in equilibrium at each of the triple points?
c. What is the stable phase at 1 atm and $100 .^{\circ} \mathrm{C} ?$
d. What are the normal melting point and the normal boiling point of sulfur?
e. Which is the densest phase?
f. At a pressure of $1.0 \times 10^{-5}$ atm, can rhombic sulfur sublime?
g. What phase changes occur when the pressure on a sample of sulfur at $100 .^{\circ} \mathrm{C}$ is increased from $1.0 \times 10^{-8}$ atm to 1500 atm?

Kevin Zaborsky

Numerade Educator

Problem 105

Use the accompanying phase diagram for carbon to answer the following questions.
a. How many triple points are in the phase diagram?
b. What phases can coexist at each triple point?
c. What happens if graphite is subjected to very high pressures at room temperature?
d. If we assume that the density increases with an increase in pressure, which is more dense, graphite or diamond?
(GRAPH CAN'T COPY)

Thomas Harr

Numerade Educator

Problem 106

Like most substances, bromine exists in one of the three typical phases. $\mathrm{Br}_{2}$ has a normal melting point of $-7.2^{\circ} \mathrm{C}$ and a normal boiling point of $59^{\circ} \mathrm{C}$. The triple point for $\mathrm{Br}_{2}$ is $-7.3^{\circ} \mathrm{C}$ and 40 torr, and the critical point is $320^{\circ} \mathrm{C}$ and 100 atm. Using this information, sketch a phase diagram for bromine indicating the points described above. Based on your phase diagram, order the three phases from least dense to most dense. What is the stable phase of $\mathrm{Br}_{2}$ at room temperature and 1 atm? Under what temperature conditions can liquid bromine never exist? What phase changes occur as the temperature of a sample of bromine at 0.10 atm is increased from $-50^{\circ} \mathrm{C}$ to $200^{\circ} \mathrm{C} ?$

Kevin Zaborsky

Numerade Educator

Problem 107

The melting point of a fictional substance $X$ is $225^{\circ} \mathrm{C}$ at 10.0 atm. If the density of the solid phase of $X$ is $2.67 \mathrm{g} / \mathrm{cm}^{3}$ and the density of the liquid phase is $2.78 \mathrm{g} / \mathrm{cm}^{3}$ at $10.0 \mathrm{atm}$, predict whether the normal melting point of X will be less than, equal to, or greater than $225^{\circ} \mathrm{C} .$ Explain.

Madi Sousa

Numerade Educator

Problem 108

Consider the following data for xenon:
Triple point: $-121^{\circ} \mathrm{C}, 280$ torr
Normal melting point: $\quad-112^{\circ} \mathrm{C}$
Normal boiling point: $\quad-107^{\circ} \mathrm{C}$
Which is more dense, Xe(s) or Xe(I)? How do the melting point and boiling point of xenon depend on pressure?

Kevin Zaborsky

Numerade Educator

Problem 109

Some of the physical properties of $\mathrm{H}_{2} \mathrm{O}$ and $\mathrm{D}_{2} \mathrm{O}$ are as follows: (TABLE CAN'T COPY)
Account for the differences. (Note: $\mathbf{D}$ is a symbol often used for $^{2} \mathrm{H},$ the deuterium isotope of hydrogen.)

Madi Sousa

Numerade Educator

Problem 110

Rationalize the following boiling points: (EQUATION CAN'T COPY)

Kevin Zaborsky

Numerade Educator

Problem 111

Consider the following vapor pressure versus temperature plot for three different substances: $\mathrm{A}, \mathrm{B},$ and $\mathrm{C}$. (TABLE CAN'T COPY) If the three substances are $\mathrm{CH}_{4}, \mathrm{SiH}_{4},$ and $\mathrm{NH}_{3},$ match each curve to the correct substance.

Shazia Naz

Numerade Educator

Problem 112

Consider the following enthalpy changes: $$\begin{aligned} \mathrm{F}^{-}+\mathrm{HF} \longrightarrow \mathrm{FHF}^{-} & \Delta H=-155 \mathrm{kJ} / \mathrm{mol} \\ \left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{O}+\mathrm{HF} \longrightarrow\left(\mathrm{CH}_{3}\right)_{2} \mathrm{C}=\mathrm{O}--\mathrm{HF} & \Delta H=-46 \mathrm{kJ} / \mathrm{mol} \\ \mathrm{H}_{2} \mathrm{O}(g)+\mathrm{HOH}(g) \longrightarrow \mathrm{H}_{2} \mathrm{O}--\mathrm{HOH}(\text { in ice }) & \Delta H=-21 \mathrm{kJ} / \mathrm{mol} \end{aligned}$$
How do the strengths of hydrogen bonds vary with the electronegativity of the element to which hydrogen is bonded? Where in the preceding series would you expect hydrogen bonds of the following type to fall?

Matthew Confer

Numerade Educator

Problem 113

The unit cell for a pure xenon fluoride compound is shown below. What is the formula of the compound?

Madi Sousa

Numerade Educator

Problem 114

Boron nitride (BN) exists in two forms. The first is a slippery solid formed from the reaction of $\mathrm{BCl}_{3}$ with $\mathrm{NH}_{3}$, followed by heating in an ammonia atmosphere at $750^{\circ} \mathrm{C}$. Subjecting the first form of BN to a pressure of 85,000 atm at $1800^{\circ} \mathrm{C}$ produces a second form that is the second hardest substance known. Both forms of BN remain solids to $3000^{\circ} \mathrm{C}$. Suggest structures for the two forms of BN.

Matthew Confer

Numerade Educator

Problem 115

Consider the following data concerning four different substances. Label the four substances as either ionic, network, metallic, or molecular solids.

MB

Marisa Bellino

Numerade Educator

Problem 116

Argon has a cubic closest packed structure as a solid. Assuming that argon has a radius of $190 . \mathrm{pm},$ calculate the density of solid argon.

Kevin Zaborsky

Numerade Educator

Problem 117

Dry nitrogen gas is bubbled through liquid benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ at $20.0^{\circ} \mathrm{C} .$ From $100.0 \mathrm{L}$ of the gaseous mixture of nitrogen and benzene, $24.7 \mathrm{g}$ benzene is condensed by passing the mixture through a trap at a temperature where nitrogen is gaseous and the vapor pressure of benzene is negligible. What is the vapor pressure of benzene at $20.0^{\circ} \mathrm{C} ?$

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Marisa Bellino

Numerade Educator

Problem 118

A $20.0-\mathrm{g}$ sample of ice at $-10.0^{\circ} \mathrm{C}$ is mixed with $100.0 \mathrm{g}$ water at $80.0^{\circ} \mathrm{C}$. Calculate the final temperature of the mixture assuming no heat loss to the surroundings. The heat capacities of $\mathrm{H}_{2} \mathrm{O}(s)$ and $\mathrm{H}_{2} \mathrm{O}(l)$ are 2.03 and $4.18 \mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C},$ respectively, and the enthalpy of fusion for ice is $6.02 \mathrm{kJ} / \mathrm{mol}$.

Kevin Zaborsky

Numerade Educator

Problem 119

In regions with dry climates, evaporative coolers are used to cool air. A typical electric air conditioner is rated at $1.00 \times$ $10^{4} \mathrm{Btu} / \mathrm{h}(1 \mathrm{Btu}, \text { or British thermal unit }=$ amount of energy to raise the temperature of 1 lb water by $1^{\circ} \mathrm{F}$ ). What quantity of water must be evaporated each hour to dissipate as much heat as a typical electric air conditioner?

Madi Sousa

Numerade Educator

Problem 120

The critical point of $\mathrm{NH}_{3}$ is $132^{\circ} \mathrm{C}$ and 111 atm, and the critical point of $\mathrm{N}_{2}$ is $-147^{\circ} \mathrm{C}$ and 34 atm. Which of these substances cannot be liquefied at room temperature no matter how much pressure is applied? Explain.

Kevin Zaborsky

Numerade Educator

Problem 121

Which of the following compound(s) exhibit only London dispersion intermolecular forces? Which compound(s) exhibit hydrogen-bonding forces? Considering only the compounds without hydrogen-bonding interactions, which compounds have dipole-dipole intermolecular forces?
a. $\mathrm{SF}_{4}$
b. $\mathrm{CO}_{2}$
c. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$
d. $\mathrm{HF}$
e. $\mathrm{ICl}_{5}$
f. $\mathrm{XeF}_{4}$

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Marisa Bellino

Numerade Educator

Problem 122

Which of the following statements about intermolecular forces is(are) true?
a. London dispersion forces are the only type of intermolecular force that nonpolar molecules exhibit.
b. Molecules that have only London dispersion forces will always be gases at room temperature $\left(25^{\circ} \mathrm{C}\right).$
c. The hydrogen-bonding forces in $\mathrm{NH}_{3}$ are stronger than those in $\mathrm{H}_{2} \mathrm{O}$.
d. The molecules in $\mathrm{SO}_{2}(g)$ exhibit dipole-dipole intermolecular interactions.
e. $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{3}$ has stronger London dispersion forces than does $\mathrm{CH}_{4}.$

Matthew Confer

Numerade Educator

Problem 123

Which of the following statements is(are) true?
a. LiF will have a higher vapor pressure at $25^{\circ} \mathrm{C}$ than $\mathrm{H}_{2} \mathrm{S}$.
b. HF will have a lower vapor pressure at $-50^{\circ} \mathrm{C}$ than HBr.
c. $\mathrm{Cl}_{2}$ will have a higher boiling point than Ar.
d. HCl is more soluble in water than in CCl_.
e. $\mathrm{MgO}$ will have a higher vapor pressure at $25^{\circ} \mathrm{C}$ than $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$

MB

Marisa Bellino

Numerade Educator

Problem 124

Aluminum has an atomic radius of $143 \mathrm{pm}$ and forms a solid with a cubic closest packed structure. Calculate the density of solid aluminum in $\mathrm{g} / \mathrm{cm}^{3} .$

Kevin Zaborsky

Numerade Educator

Problem 125

Pyrolusite is a mineral containing manganese ions and oxide ions. Its structure can best be described as a body-centered cubic array of manganese ions with two oxide ions inside the unit cell and two oxide ions each on two faces of the cubic unit cell. What is the charge on the manganese ions in pyrolusite?

Madi Sousa

Numerade Educator

Problem 126

The structure of the compound $\mathrm{K}_{2} \mathrm{O}$ is best described as a cubic closest packed array of oxide ions with the potassium ions in tetrahedral holes. What percent of the tetrahedral holes are occupied in this solid?

Kevin Zaborsky

Numerade Educator

Problem 127

What type of solid (network, metallic, Group $8 \mathrm{A},$ ionic, or molecular) will each of the following substances form?
a. $\mathrm {K r}$
b. $\mathrm{SO}_{2}$
c. $\mathrm {Ni}$
d. $\mathrm{SiO}_{2}$
e. $\mathrm{NH}_{3}$
f. $\mathrm{Pt}$

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Marisa Bellino

Numerade Educator

Problem 128

Some ice cubes at $0^{\circ} \mathrm{C}$ with a total mass of $403 \mathrm{g}$ are placed in a microwave oven and subjected to $750 . \mathrm{W}(750 . \mathrm{J} / \mathrm{s})$ of energy for 5.00 minutes. What is the final temperature of the water? Assume all the energy of the microwave is absorbed by the water, and assume no heat loss by the water.

Kevin Zaborsky

Numerade Educator

Problem 129

The enthalpy of vaporization for acetone is $32.0 \mathrm{kJ} / \mathrm{mol}$. The normal boiling point for acetone is $56.5^{\circ} \mathrm{C}$. What is the vapor pressure of acetone at $23.5^{\circ} \mathrm{C} ?$

Madi Sousa

Numerade Educator

Problem 130

Choose the statements that correctly describe the following phase diagram.
a. If the temperature is raised from $50 \mathrm{K}$ to $400 \mathrm{K}$ at a pressure of 1 atm, the substance boils at approximately $185 \mathrm{K}$.
b. The liquid phase of this substance cannot exist under conditions of 2 atm at any temperature.
c. The triple point occurs at approximately $165 \mathrm{K}$.
d. At a pressure of 1.5 atm, the melting point of the substance is approximately $370 \mathrm{K}$.
e. The critical point occurs at approximately 1.7 atm and $410 \mathrm{K}$.

Kevin Zaborsky

Numerade Educator

Problem 131

When 1 mole of benzene is vaporized at a constant pressure of 1.00 atm and at its boiling point of $353.0 \mathrm{K}, 30.79 \mathrm{kJ}$ of energy (heat) is absorbed and the volume change is +28.90 L. What are $\Delta E$ and $\Delta H$ for this process?

Madi Sousa

Numerade Educator

Problem 132

You and a friend each synthesize a compound with the formula $\mathrm{XeCl}_{2} \mathrm{F}_{2}$. Your compound is a liquid and your friend's compound is a gas (at the same conditions of temperature and pressure). Explain how the two compounds with the same formulas can exist in different phases at the same conditions of pressure and temperature.

Kevin Zaborsky

Numerade Educator

Problem 133

Using the heats of fusion and vaporization for water given in Exercise $99,$ calculate the change in enthalpy for the sublimation of water: $$\mathrm{H}_{2} \mathrm{O}(s) \longrightarrow \mathrm{H}_{2} \mathrm{O}(g)$$ Using the $\Delta H$ value given in Exercise 112 and the number of hydrogen bonds formed with each water molecule, estimate what portion of the intermolecular forces in ice can be accounted for by hydrogen bonding.

Madi Sousa

Numerade Educator

Problem 134

Consider a perfectly insulated and sealed container. Determine the minimum volume of a container such that a gallon of water at $25^{\circ} \mathrm{C}$ will evaporate completely. If the container is a cube, determine the dimensions in feet. Assume the density of water is $0.998 \mathrm{g} / \mathrm{cm}^{3}.$

Matthew Confer

Numerade Educator

Problem 135

Consider two different organic compounds, each with the formula $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}$. One of these compounds is a liquid at room conditions and the other is a gas. Write Lewis structures consistent with this observation, and explain your answer. (Hint: The oxygen atom in both structures satisfies the octet rule with two bonds and two lone pairs.)

MB

Marisa Bellino

Numerade Educator

Problem 136

Rationalize the differences in physical properties in terms of intermolecular forces for the following organic compounds. Compare the first three substances with each other, compare the last three with each other, and then compare all six. Can you account for any anomalies?

Matthew Confer

Numerade Educator

Problem 137

Consider the following melting point data: Account for the trends in melting points in terms of interparticle forces.

Madi Sousa

Numerade Educator

Problem 138

Some ionic compounds contain a mixture of different charged cations. For example, wüstite is an oxide that contains both $\mathrm{Fe}^{2+}$ and $\mathrm{Fe}^{3+}$ cations and has a formula of $\mathrm{Fe}_{0.950} \mathrm{O}_{1.00}$. Calculate the fraction of iron ions present as $\mathrm{Fe}^{3+} .$ What fraction of the sites normally occupied by $\mathrm{Fe}^{2+}$ must be vacant in this solid?

Matthew Confer

Numerade Educator

Problem 139

Some ionic compounds contain a mixture of different charged cations. For example, some titanium oxides contain a mixture of $\mathrm{Ti}^{2+}$ and $\mathrm{Ti}^{3+}$ ions. Consider a certain oxide of titanium that is $28.31 \%$ oxygen by mass and contains a mixture of $\mathrm{Ti}^{2+}$ and $\mathrm{Ti}^{3+}$ ions. Determine the formula of the compound and the relative numbers of $\mathrm{Ti}^{2+}$ and $\mathrm{Ti}^{3+}$ ions.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 140

Spinel is a mineral that contains $37.9 \%$ aluminum, $17.1 \%$ magnesium, and $45.0 \%$ oxygen, by mass, and has a density of $3.57 \mathrm{g} / \mathrm{cm}^{3} .$ The edge of the cubic unit cell measures $809 \mathrm{pm} .$ How many of each type of ion are present in the unit cell?

Kevin Zaborsky

Numerade Educator

Problem 141

Mn crystallizes in the same type of cubic unit cell as Cu. Assuming that the radius of Mn is $5.6 \%$ larger than the radius of Cu and the density of copper is $8.96 \mathrm{g} / \mathrm{cm}^{3},$ calculate the density of Mn.

Madi Sousa

Numerade Educator

Problem 142

You are asked to help set up a historical display in the park by stacking some cannonballs next to a Revolutionary War cannon. You are told to stack them by starting with a triangle in which each side is composed of four touching cannonballs. You are to continue stacking them until you have a single ball on the top centered over the middle of the triangular base.
a. How many cannonballs do you need?
b. What type of closest packing is displayed by the cannonballs?
c. The four corners of the pyramid of cannonballs form the corners of what type of regular geometric solid?

Matthew Confer

Numerade Educator

Problem 143

Some water is placed in a sealed glass container connected to a vacuum pump (a device used to pump gases from a container), and the pump is turned on. The water appears to boil and then freezes. Explain these changes using the phase diagram for water. What would happen to the ice if the vacuum pump was left on indefinitely?

David Collins

Numerade Educator

Problem 144

The molar enthalpy of vaporization of water at $373 \mathrm{K}$ and 1.00 atm is $40.7 \mathrm{kJ} / \mathrm{mol} .$ What fraction of this energy is used to change the internal energy of the water, and what fraction is used to do work against the atmosphere? (Hint: Assume that water vapor is an ideal gas.)

Matthew Confer

Numerade Educator

Problem 145

For a simple cubic array, solve for the volume of an interior sphere (cubic hole) in terms of the radius of a sphere in the array.

Madi Sousa

Numerade Educator

Problem 146

Rubidium chloride has the sodium chloride structure at normal pressures but assumes the cesium chloride structure at high pressures. (See Exercise 69.) What ratio of densities is expected for these two forms? Does this change in structure make sense on the basis of simple models? The ionic radius is $148 \mathrm{pm}$ for $\mathrm{Rb}^{+}$ and $181 \mathrm{pm}$ for $\mathrm{Cl}^{-}.$

Matthew Confer

Numerade Educator

Problem 147

A 0.132 -mole sample of an unknown semiconducting material with the formula XY has a mass of $19.0 \mathrm{g}$. The element X has an electron configuration of $[\mathrm{Kr}] 5 s^{2} 4 d^{10} .$ What is this semiconducting material? A small amount of the Y atoms in the semiconductor is replaced with an equivalent amount of atoms with an electron configuration of $[\mathrm{Ar}] 4 s^{2} 3 d^{10} 4 p^{5} .$ Does this correspond to n-type or p-type doping?

Madi Sousa

Numerade Educator

Problem 148

A metal burns in air at $600^{\circ} \mathrm{C}$ under high pressure to form an oxide with formula $\mathrm{MO}_{2}$. This compound is $23.72 \%$ oxygen by mass. The distance between the centers of touching atoms in a cubic closest packed crystal of this metal is $269.0 \mathrm{pm} .$ What is this metal? What is its density?

Kevin Zaborsky

Numerade Educator

Problem 149

One method of preparing elemental mercury involves roasting cinnabar (HgS) in quicklime (CaO) at 600.^ C followed by condensation of the mercury vapor. Given the heat of vaporization of mercury (296 J/g) and the vapor pressure of mercury at $25.0^{\circ} \mathrm{C}\left(2.56 \times 10^{-3} \text {torr }\right),$ what is the vapor pressure of the condensed mercury at $300 .^{\circ} \mathrm{C} ?$ How many atoms of mercury are present in the mercury vapor at $300 .^{\circ} \mathrm{C}$ if the reaction is conducted in a closed 15.0 -L container?

Madi Sousa

Numerade Educator

Problem 150

General Zod has sold Lex Luthor what Zod claims to be a new copper-colored form of kryptonite, the only substance that can harm Superman. Lex, not believing in honor among thieves, decided to carry out some tests on the supposed kryptonite. From previous tests, Lex knew that kryptonite is a metal having a specific heat capacity of $0.082 \mathrm{J} / \mathrm{g} \cdot^{\circ} \mathrm{C}$ and a density of $9.2 \mathrm{g} / \mathrm{cm}^{3}.$ Lex Luthor's first experiment was an attempt to find the specific heat capacity of kryptonite. He dropped a $10 \mathrm{g} \pm 3 \mathrm{g}$ sample of the metal into a boiling water bath at a temperature of $100.0^{\circ} \mathrm{C} \pm 0.2^{\circ} \mathrm{C} .$ He waited until the metal had reached the bath temperature and then quickly transferred it to $100 \mathrm{g} \pm 3 \mathrm{g}$ of water that was contained in a calorimeter at an initial temperature of $25.0^{\circ} \mathrm{C} \pm 0.2^{\circ} \mathrm{C} .$ The final temperature of the metal and water was $25.2^{\circ} \mathrm{C} .$ Based on these results, is it possible to distinguish between copper and kryptonite? Explain. When Lex found that his results from the first experiment were inconclusive, he decided to determine the density of the sample. He managed to steal a better balance and determined the mass of another portion of the purported kryptonite to be $4 \mathrm{g} \pm 1$ g. He dropped this sample into water contained in a 25-mL graduated cylinder and found that it displaced a volume of $0.42 \mathrm{mL} \pm 0.02 \mathrm{mL} .$ Is the metal copper or kryptonite? Explain. Lex was finally forced to determine the crystal structure of the metal General Zod had given him. He found that the cubic unit cell contained four atoms and had an edge length of $600 . \mathrm{pm} .$ Explain how this information enabled Lex to identify the metal as copper or kryptonite. Will Lex be going after Superman with the kryptonite or seeking revenge on General Zod? What improvements could he have made in his experimental techniques to avoid performing the crystal structure determination?

Prashant Bana

Numerade Educator