Chemistry Principles and Reactions

William L Masterton; Cecile N Hurley; Edward J Neth

Chapter 9

Liquids and Solids - all with Video Answers

Educators

Chapter Questions

Problem 1

Methyl alcohol can be used as a fuel instead of, or combined with, gasoline. A sample of methyl alcohol, CH,OH, in a flask of constant volume exerts. a pressure of $254 \mathrm{~mm} \mathrm{Hg}$ at $57^{\circ} \mathrm{C}$. The flask is slowly cooled.
(a) Assuming no condensation, use the ideal gas law to calculate the pressure of the vapor at $35^{\circ} \mathrm{C}_{;}$ at $45^{\circ} \mathrm{C}$
(b) Compare your answers in (a) with the equilibrium vapor pressures of methyl alcohol: $203 \mathrm{~mm} \mathrm{Hg}$ at $35^{\circ} \mathrm{C}_{i} 325 \mathrm{~mm} \mathrm{Hg}$ at $45^{\circ} \mathrm{C} .$
(c) On the basis of your answers to (a) and (b), predict the pressure exerted by the methyl alcohol in the flask at $35^{\circ} \mathrm{C}_{;}$ at $45^{\circ} \mathrm{C}$.
(d) What physical states of methyl alcohol are present in the flask at $35^{\circ} \mathrm{C} ?$ at $45^{\circ} \mathrm{C} ?$

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Problem 2

Benzene, a known carcinogen, was once widely used as a solvent. $A$ sample of benzene vapor in a flask of constant volume exerts a pressure of $325 \mathrm{~mm} \mathrm{Hg}$ at $80^{\circ} \mathrm{C}$. The flask is slowly cooled.
(a) Assuming no condensation, use the ideal gas law to calculate the pressure of the vapor at $50^{\circ} \mathrm{C}$; at $60^{\circ} \mathrm{C}$
(b) Compare your answers in (a) to the equilibrium vapor pressures of benzene: $269 \mathrm{~mm} \mathrm{Hg}$ at $50^{\circ} \mathrm{C}, 389 \mathrm{~mm} \mathrm{Hg}$ at $60^{\circ} \mathrm{C}$
(c) On the basis of your answers to (a) and (b), predict the pressure exerted by the benzene at $50^{\circ} \mathrm{C}_{3}$ at $60^{\circ} \mathrm{C}$

Eileen Sullivan

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Problem 3

Naphthalene, $\mathrm{C}_{10} \mathrm{H}_{3}$, is the substance present in some moth balls. Its. vapor pressure at $25^{\circ} \mathrm{C}$ is $0.300 \mathrm{~mm} \mathrm{Hg}$.
(a) How many milligrams of naphthalene will sublime into an evacuated $1.000-1$. flask?
(b) If $0.700 \mathrm{mg}$ of naphthalene is used, what will the final pressure be? What physical state(s) of naphthalene is (are) in the flask?
(c) If $4.00 \mathrm{mg}$ of naphthalene is used, what will the final pressure be? What physical state(s) of naphthalene is (are) in the flask?

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Problem 4

Camphor, $\mathrm{C}_{10} \mathrm{H}_{16} \mathrm{O}$, is the active ingredient in vapor-steam products like Vicks VapoRubs. Its vapor pressure at $20^{\circ} \mathrm{C}$ is $0.18 \mathrm{~mm} \mathrm{Hg}$.
(a) How many milligrams of camphor will sublime into an evacuated $0.500-L$ flask?
(b) A $125-\mathrm{mL}$. flask contains $0.15 \mathrm{mg}$ of camphor at $20^{\circ} \mathrm{C}$. What is the pressure in the flask?

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Problem 5

The vapor pressure of bromine, $\mathrm{Br}_{2}(l)$ at $25^{\circ} \mathrm{C}$ is $228 \mathrm{~mm} \mathrm{Hg}$.
(a) How many grams of bromine will be present as a gas if liquid bromine is poured into an evacuated $2.00-\mathrm{L}$ flask at $25^{\circ} \mathrm{C} ?$
(b) If $2.00 \mathrm{~g}$ of bromine are used, what is the final pressure in the flask? Will there be liquid in the flask?
(c) If $2.00 \mathrm{~g}$ of bromine are put into an evacuated $750.0-\mathrm{mL}$ flask at $25^{\circ} \mathrm{C}$, what is the final pressure in the flask? Will there be any liquid in the flask?

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Problem 6

$p$ -Dichlorobenzene, $\mathrm{C}_{6} \mathrm{H}_{4} \mathrm{Cl}_{2}$, can be one of the ingredients in mothballs. Its vapor pressure at $20^{\circ} \mathrm{C}$ is $0.40 \mathrm{~mm} \mathrm{Hg}$.
(a) How many milligrams of $\mathrm{C}_{6} \mathrm{H}_{4} \mathrm{Cl}_{2}$ will sublime into an evacuated $750-\mathrm{mL}$ tlask at $20^{\circ} \mathrm{C} ?$
(b) If $5.0 \mathrm{mg}$ of $p$ -dichlorobenzene were put into an evacuated $750-\mathrm{mL}$ flask, how many milligrams would remain in the solid phase?
(c) What is the final pressure in an evacuated $500-\mathrm{mL}$ flask at $20^{\circ} \mathrm{C}$ that contains $2.00 \mathrm{mg}$ of $p$ -dichlorobenzene? Will there be any solid in the flask?

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Problem 7

Chloroform, CHCl, was once used as an anesthetic. In spy movies it is the liquid put in handkerchiefs to render victims unconscious. Its vapor pressure is $197 \mathrm{~mm} \mathrm{Hg}$ at $23^{\circ} \mathrm{C}$ and $448 \mathrm{~mm} \mathrm{Hg}$ at $45^{\circ} \mathrm{C}$. Estimate its
(a) heat of vaporization.
(b) normal boiling point.

Eileen Sullivan

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Problem 8

Dichloromethane, $\mathrm{CH}_{2} \mathrm{Cl}_{2}$, is widely used as a "degreaser" and paint stripper. Its vapor pressure is $381.0 \mathrm{~mm} \mathrm{Hg}$ at $21.9^{\circ} \mathrm{C}$ and $465.8 \mathrm{~mm} \mathrm{Hg}$ at $26.9^{\circ} \mathrm{C}$. Estimate
(a) its heat of vaporization $\left(\Delta H_{\text {vap }}\right)$.
(b) its normal boiling point.

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Problem 9

Mt. McKinley in Alaska has an altitude of $20,320 \mathrm{ft} .$ Water $\left(\Delta H_{\text {vap }}=\right.$ $40.7 \mathrm{~kJ} / \mathrm{mol}$ ) boils in $77^{\circ} \mathrm{C}$ atop Mt. McKinley. What is the normal atmospheric pressure at the summit?

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Problem 10

Glacier National Park in Montana is a favorite vacation spot for backpackers. It is about $4100 \mathrm{ft}$ above sea level with an atmospheric pressure of $681 \mathrm{~mm} \mathrm{Hg} .$ At what temperature does water $\left(\Delta H_{v a p}=40.7 \mathrm{k} \mathrm{J} / \mathrm{mol}\right)$ boil in Glacier National Park?

Eileen Sullivan

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Problem 11

At a resort in Sante Fe, New Mexico, the barometric pressure is $625 \mathrm{~mm} \mathrm{Hg} .$ Water boils in an open pot at $94.5^{\circ} \mathrm{C}$. A pressure cooker is set for 1.75 atm.
(a) At what temperature will water boil in that pressure cooker? (For water, $\left.\Delta H_{\text {vap }}=40.7 \mathrm{~kJ} / \mathrm{mol} .\right)$
(b) What is the difference between the boiling point in the open pot and in the pressure cooker?

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Problem 12

When water boils in a pressure cooker, its vapor pressure is $1.500 \times 10^{3}$ $\mathrm{mm} \mathrm{Hg}$. What is the boiling point of water in the pressure cooker? Take $\Delta H_{\text {vap }}$ for water to be $40.7 \mathrm{~kJ} / \mathrm{mol}$.

Eileen Sullivan

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Problem 13

The data below give the vapor pressure of octane, a major component of gasoline. $\begin{array}{lllcl}\mathrm{vp}(\mathrm{mm} \mathrm{Hg}) & 10 & 40 & 100 & 400 \\ t\left({ }^{\circ} \mathrm{C}\right) & 19.2 & 45.1 & 65.7 & 104.0\end{array}$
Plot $\ln (v p)$ versus $1 / T$. Use your graph to estimate the heat of vaporization of $\left(\ln P=A-\frac{\Delta H_{\mathrm{vap}}}{R}\left(\frac{1}{T}\right)\right.$ octane. $\left(\ln P=A-\frac{1}{T}\right),$ where $A$ is the $y$ -intercept and $\Delta H_{\text {vap }}$ is the slope.)

Eileen Sullivan

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Problem 14

Consider the following data for the vapor pressure of diethyl ether, a widely used anesthetic in the early days of surgery.
$\begin{array}{llrrr}\mathrm{vp}(\mathrm{mm} \mathrm{Hg}) & 146 & 231 & 355 & 531 \\ t\left({ }^{\circ} \mathrm{C}\right) & -5 & 5 & 15 & 25\end{array}$ Follow the instructions in Question 13 to estimate the heat of vaporization of diethyl ether.

Eileen Sullivan

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Problem 15

Referring to Figure 9.6 , state what phase(s) is (are) prestint at
(a) $-30^{\circ} \mathrm{C}, 5 \mathrm{~mm} \mathrm{Hg}$
(b) $25^{\circ} \mathrm{C}, 1 \mathrm{~atm}$
(c) $70^{\circ} \mathrm{C}, 20 \mathrm{~mm} \mathrm{Hg}$

Eileen Sullivan

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Problem 16

Referring to Figure $9.6,$ state what phase(s) is (are) present at
(a) $1 \mathrm{~atm}, 10^{\circ} \mathrm{C}$
(b) $3 \mathrm{~mm} \mathrm{Hg}, 20^{\circ} \mathrm{C}$
(c) $1000 \mathrm{~mm} \mathrm{Hg}, 75^{\circ} \mathrm{C}$

Eileen Sullivan

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Problem 17

Consider the phase diagram for $\mathrm{CCl}_{4}$ below. Answer the questions about the diagram by writing your answers in the blanks provided.
(a) What point (not including the triple point) represents an equilibrium between the solid and the vapor phases?
(b) What is $\mathrm{CCl}_{4}$ at point $G$ called?
(c) Does the boiling point increase as pressure above the liquid is decreased? (Yes or No)
(d) What point represents $\mathrm{CCl}_{4}$ only in the gas phase?
(e) Does the melting point increase as pressure is applied to the solid? (Yes or No)
(f) Is sublimation of $\mathrm{CCl}_{4}$ impossible at any pressure? (Yes or No)
(g) For a specific temperature above point $E$, is the density of the liquid phase larger than the density of the solid phase? (Yes or No)

Eileen Sullivan

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Problem 18

Consider the phase diagram of the compound below to answer the following questions.
(a) What is the physical state of the compound at $35 \mathrm{~mm} \mathrm{Hg}$ and $120^{\circ} \mathrm{C} ?$
(b) What is the normal freezing point of the compound?
(c) What is the point $A$ called?
(d) What is the point $B$ called?
(e) What is the point $C$ called?
(f) What change occurs when at a constant pressure of $33 \mathrm{~mm} \mathrm{Hg},$ the temperature is decreased from $40^{\circ} \mathrm{C}$ to $-20^{a} C ?$
(g) Will the solid float on the liquid?
(h) Can the compound exist as a liquid at $180^{\circ} \mathrm{C}$ and $2 \mathrm{~atm}$ pressure?

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Problem 19

Argon gas has its triple point at $-189.3^{\circ} \mathrm{C}$ and $516 \mathrm{~mm} \mathrm{Hg}$. It has a critical point at $-122^{\circ} \mathrm{C}$ and $48 \mathrm{~atm} .$ The density of the solid is $1.65 \mathrm{~g} / \mathrm{cm}^{3},$ whereas that of the liquid is $1.40 \mathrm{~g} / \mathrm{cm}^{3}$. Sketch the phase diagram for argon and use it to fill in the blanks below with the words "boils, "melts," "sublimes, or
"condenses."
(a) Solid argon at $500 \mathrm{~mm} \mathrm{Hg}$ when the temperature is increased.
(b) Solid argon at $2 \mathrm{~atm}$ when the temperature is increased.
(c) Argon gas at $-150^{\circ} \mathrm{C} \longrightarrow$ when the pressure is increased.
(d) Argon gas at - $165^{\circ} \mathrm{C}$ when the pressure is increased.

Eileen Sullivan

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Problem 20

Iodine has a triple point at $114^{\circ} \mathrm{C}, 90 \mathrm{~mm} \mathrm{Hg}$. Its critical temperature is $535^{\circ} \mathrm{C}$. The density of the solid is $4.93 \mathrm{~g} / \mathrm{cm}^{3},$ and that of the liquid is $4.00 \mathrm{~g} / \mathrm{cm}^{3} .$ Sketch the phase diagram for iodine and use it to fill in the blanks using either "liquid" or "solid."
(a) Iodine vapor at $80 \mathrm{~mm} \mathrm{Hg}$ condenses to the when cooled
sufficiently.
(b) Iodine vapor at $125^{\circ} \mathrm{C}$ condenses to the $\quad$ when enough pressure is applied.
(c) Iodine vapor at $700 \mathrm{~mm} \mathrm{Hg}$ condenses to the when
cooled above the triple point temperature.

Eileen Sullivan

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Problem 21

Given the following data about xenon, $$ \begin{array}{l} \text { normal boiling point }=-108^{\circ} \mathrm{C} \\ \text { normal melting point }=-112^{\circ} \mathrm{C} \\ \text { triple point }=-121^{\circ} \mathrm{C} \text { at } 281 \mathrm{~mm} \mathrm{Hg} \\ \text { critical point }=16.6^{\circ} \mathrm{C} \text { at } 58 \mathrm{~atm} \end{array} $$
(a) Construct an approximate phase diagram for xenon.
(b) Estimate the vapor pressure of xenon at $-115^{\circ} \mathrm{C}$.
(c) Is the density of solid Xe larger than that for liquid Xe?

Nicole Smina

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Problem 22

Given the following data about ammonia,
$$ \begin{array}{l} \text { normal boiling point }=-33^{\circ} \mathrm{C} \\ \text { normal melting point }=-78^{\circ} \mathrm{C} \\ \text { triple point }=-78^{\circ} \mathrm{C} \text { at } 46 \mathrm{~mm} \mathrm{Hg} \\ \text { critical point }=132^{\circ} \mathrm{C} \text { at } 112 \mathrm{~atm} \end{array} $$
(a) Construct an approximate phase diagram for ammonia.
(b) Estimate the vapor pressure of ammonia at $40^{\circ} \mathrm{C}$.

Eileen Sullivan

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Problem 23

A pure substance $X$ has the following properties: $\mathrm{mp}=90^{\circ} \mathrm{C}$, increasing slightly as pressure increases; normal bp $=120^{\circ} \mathrm{C}$; liquid $v p=65 \mathrm{~mm} \mathrm{Hg}$ at $100^{\circ} \mathrm{C}, 20 \mathrm{~mm} \mathrm{Hg}$ at the triple point.
(a) Draw a phase diagram for $\mathrm{X}$.
(b) Label solid, liquid, and vapor regions of the diagram.
(c) What changes occur if, at a constant pressure of $100 \mathrm{~mm} \mathrm{Hg}$, the temperature is raised from $100^{\circ} \mathrm{C}$ to $150^{\circ} \mathrm{C} ?$

Eileen Sullivan

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Problem 24

A pure substance A has a liquid vapor pressure of $320 \mathrm{~mm} \mathrm{Hg}$ at $125^{\circ} \mathrm{C}$, $800 \mathrm{~mm} \mathrm{Hg}$ at $150^{\circ} \mathrm{C},$ and $60 \mathrm{~mm} \mathrm{Hg}$ at the triple point, $85^{\circ} \mathrm{C}$. The melting point of A decreases slightly as pressure increases.
(a) Sketch a phase diagram for A.
(b) From the phase diagram, estimate the boiling point.
(c) What changes occur when, at a constant pressure of $320 \mathrm{~mm} \mathrm{Hg}$, the temperature drops from $150^{\circ} \mathrm{C}$ to $100^{\circ} \mathrm{C} ?$

Eileen Sullivan

Eileen Sullivan

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Problem 25

Arrange the following in order of decreasing boiling point.
(a) $\mathrm{I}_{2}$
(b) $\bar{F}_{2}$
(c) $\mathrm{Cl}_{2}$
(d) $\mathrm{Br}_{2}$

Nicole Smina

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Problem 26

Arrange the following compounds in order of decreasing boiling points.
(a) $\mathrm{CH}_{4}$
(b) $\mathrm{CCl}_{4}$
(c) $\mathrm{CF}_{4}$
(d) $\mathrm{CBr}_{4}$

Eileen Sullivan

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Problem 27

Which of the following would you expect to show dispersion forces? dipole forces?
(a) $\mathrm{GeBr}_{4}$
(b) $\mathrm{C}_{2} \mathrm{H}_{2}$
(c) HF $(g)$
(d) $\mathrm{TeCl}_{2}$

Nicole Smina

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Problem 28

Which of the following compounds would you expect to show dispersion forces? Dipole forces?
(a) $\mathrm{F}_{2}$
(b) $\mathrm{CO}$
(c) $\mathrm{CO}_{2}$
(d) $\mathrm{H}_{2} \mathrm{CO}$

Nicole Smina

Numerade Educator

Problem 29

Which of the following would show hydrogen bonding?
(a) $\mathrm{CH}_{3} \mathrm{OH}$
(b) <smiles>CN(C)C</smiles>
(c) $\mathrm{CH}_{3} \mathrm{NH}_{2}$
(d) $\mathrm{HF}$

Eileen Sullivan

Eileen Sullivan

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Problem 30

Which of the following compounds show hydrogen bonding?
(a) $[\mathrm{H}-\mathrm{F}-\mathrm{F}]^{+}$
(b) $\mathrm{CH}_{3} \mathrm{CN}$
(c) $\mathrm{HO}-\mathrm{OH}$
(d) $\mathrm{CH}_{3}-\mathrm{O}-\mathrm{CH}_{3}$

Eileen Sullivan

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Problem 31

Explain in terms of forces between structural units why
(a) HI has a higher boiling point than HBr.
(b) $\mathrm{GeH}_{4}$ has a higher boiling point than $\mathrm{SiH}_{4}$.
(c) $\mathrm{H}_{2} \mathrm{O}_{2}$ has a higher melting point than $\mathrm{C}_{3} \mathrm{H}_{\mathrm{B}}$.
(d) $\mathrm{NaCl}$ has a higher boiling point than $\mathrm{CH}_{3} \mathrm{OH}$.

Eileen Sullivan

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Problem 32

Explain in terms of structural units why
(a) $\mathrm{CO}_{2}$ has a lower boiling point than $\mathrm{Na}_{2} \mathrm{CO}_{3}$.
(b) $\mathrm{N}_{2} \mathrm{H}_{4}$ has a higher boiling point than $\mathrm{C}_{2} \mathrm{H}_{6}$
(c) formic acid, $\mathrm{H}-\mathrm{C}-\mathrm{OH}$, has a lower boiling point than benzoic
<smiles>O=C(O)C(=O)O</smiles>
acid,
<smiles>O=C(O)Cc1ccccc1</smiles>
(d) CO has a higher boiling point than $\mathrm{N}_{2}$.

Eileen Sullivan

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Problem 33

In which of the following processes is it necessary to break covalent bonds as opposed to simply overcoming intermolecular forces?
(a) melting mothballs made of naphthalene
(b) dissolving HBr gas in water to form hydrobromic acid
(c) vaporizing ethyl alcohol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$
(d) changing ozone, $\mathrm{O}_{3},$ to oxygen gas, $\mathrm{O}_{2}$

Nicole Smina

Numerade Educator

Problem 34

In which of the following processes is it necessary to break covalent bonds as opposed to simply overcoming intermolecular forces?
(a) subliming dry ice
(b) vaporizing chloroform (CHCly)
(c) decomposing water into $\mathrm{H}_{2}$ and $\mathrm{O}_{2}$
(d) changing chlorine molecules into chlorine atoms

Eileen Sullivan

Eileen Sullivan

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Problem 35

For each of the following pairs, choose the member with the lower boiling point. Explain your reason in each case.
(a) $\mathrm{NaCl}$ or $\mathrm{PCl}_{3}$
(b) $\mathrm{NH}_{3}$ or $\mathrm{AsH}_{3}$
(c) $\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH}$ or $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OCH}_{3}$
(d) $\mathrm{HI}(g)$ or $\mathrm{HCl}(g)$

Daniel Gosser

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Problem 36

Follow the directions of Question 35 for the following compounds.
(a) $\mathrm{NaO}_{2}$ or $\mathrm{SO}_{2}$
(b) Xe or Ne
(c) $\mathrm{CH}_{4}$ or $\mathrm{CCl}_{4}$
(d) $\mathrm{NH}_{3}$ or $\mathrm{AsH}_{3}$

Eileen Sullivan

Eileen Sullivan

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Problem 37

What are the strongest attractive forces that must be overcome to
(a) boil silicon hydride, $\mathrm{SiH}_{4} ?$
(b) vaporize calcium chloride?
(c) dissolve $\mathrm{Cl}_{2}$ in carbon tetrachloride, $\mathrm{CCl}_{4} ?$
(d) melt iodine?

Nicole Smina

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Problem 38

What are the strongest attractive forces that must be overcoure to
(a) melt ice?
(b) sublime bromine?
(c) boil chloroform (CHCl_)?
(d) vaporize benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ ?

Eileen Sullivan

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Problem 39

Classify each of the following solids as metallic, network covalent, ionic, or molecular.
(a) It is insoluble in water, melts above $500^{\circ} \mathrm{C}$, and does not conduct
electricity either as a solid, dissolved in water, or molten.
(b) It dissolves in water but does not conduct electricity as an aqueous solution, as a solid, or when molten.
(c) It dissolves in water, melts above $100^{\circ} \mathrm{C}$, and conducts electricity when present in an aqueous solution.

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Problem 40

Classify each of the following solids as metallic, network covalent, ionic, or molecular.
(a) It dissolves in water, conducts electricity when dissolved in water and melts above $100^{\circ} \mathrm{C}$.
(b) It is malleable and conducts electricity.
(c) It has dipole forces and is made up only of nonmetal atoms.
(d) It melts above $500^{\circ} \mathrm{C}$ and is made up only of nonmetal atoms.

Eileen Sullivan

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Problem 41

Of the four general types of solids, which one(s)
(a) are generally low-boiling?
(b) are ductile and malleable?
(c) are generally soluble in nonpolar solvents?

Eileen Sullivan

Eileen Sullivan

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Problem 42

Of the four general types of solids, which one(s)
(a) are generally insoluble in water?
(b) have very high melting points?
(c) conduct electricity as solids?

Nicole Smina

Numerade Educator

Problem 43

. Classify each of the following species as molecular, network covalent, ionic, or metallic.
(a) $\mathrm{Na}$
(b) $\mathrm{Na}_{2} \mathrm{SO}_{4}$
(c) $\mathrm{C}_{6} \mathrm{H}_{6}$
(d) $\mathrm{C}_{60}$
[e) HClle

Eileen Sullivan

Eileen Sullivan

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Problem 44

. Classify each of the species as metallic, network covalent, ionic, or molecular.
(a) sand
(b) Ca
(c) C (diamond)
(d) $\mathrm{ICl}$
(e) $\mathrm{CaCl}_{2}$

Eileen Sullivan

Eileen Sullivan

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Problem 45

Give the formula of a solid containing carbon that is
(a) molecular
(b) ionic
(c) network covalent
(d) metallic

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Eileen Sullivan

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Problem 46

Give the formula of a solid containing oxygen that is
(a) a polar molecule
(b) ionic
(c) network covalent
(d) a nonpolar molecule

Nicole Smina

Numerade Educator

Problem 47

Describe the structural units in
(a) NaI
(b) $\mathrm{N}_{2}$
(c) $\mathrm{KO}_{2}$
(d) $A u$

Eileen Sullivan

Eileen Sullivan

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Problem 48

Describe the structural units in
(a) $\mathrm{CH}_{2} \mathrm{Cl}_{2}$
(b) $\mathrm{Al}_{2} \mathrm{O}_{3}$
(c) $\mathrm{Al}$
(d) graphite

Eileen Sullivan

Eileen Sullivan

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Problem 49

. Molybdenum has an atomic radius of $0.145 \mathrm{nm}$. The volume of its cubic unit cell is $0.0375 \mathrm{nm}^{3}$. What is the geometry of the molybdenum unit cell?

Eileen Sullivan

Eileen Sullivan

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Problem 50

Nickel has an atomic radius of $0.162 \mathrm{nm}$. The edge of its cubic unit cell is $0.458 \mathrm{nm} .$ What is the geometry of the nickel unit cell?

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Problem 51

Lead (atomic radius $=0.181 \mathrm{nm}$ ) crystallizes with a face-centered cubic unit cell. What is the length of a side of the cell?

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Eileen Sullivan

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Problem 52

Bromine crystallizes with a body-centered cubic unit cell. The volume of the unit cell is $0.127 \mathrm{nm}^{3}$. What is its atomic radius?

Eileen Sullivan

Eileen Sullivan

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Problem 53

In the LiCl structure shown in Figure $9.19,$ the chloride ions form a facecentered cubic unit cell $0.513 \mathrm{nm}$ on an edge. The ionic radius of $\mathrm{Cl}^{-}$ is $0.181 \mathrm{nm}$
(a) Along a cell edge, how much space is between the $\mathrm{Cl}^{-}$ ions?
(b) Would an $\mathrm{Na}^{+}$ ion $(r=0.095 \mathrm{nm})$ fit into this space? a $\mathrm{K}^{+}$ ion $(r=0.133 \mathrm{nm}) ?$

Eileen Sullivan

Eileen Sullivan

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Problem 54

Potassium iodide has a unit cell similar to that of sodium chloride (Figure 9.19 ). The ionic radii of $\mathrm{K}^{+}$ and $\mathrm{I}^{-}$ are $0.133 \mathrm{nm}$ and $0.216 \mathrm{nm},$ respectively. How long is
(a) one side of the cube?
(b) the face diagonal of the cube?

Eileen Sullivan

Eileen Sullivan

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Problem 55

For a cell of the CsCl type (Figure 9.19 ), how is the length of one side of the cell, $s$, related to the sum of the radii of the ions, $r_{\text {cation }}+r_{\text {anion }} ?$

Eileen Sullivan

Eileen Sullivan

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Problem 56

. Consider the CsCl cell (Figure 9.19 ). The ionic radii of $\mathrm{Cs}^{+}$ and $\mathrm{Cl}^{-}$ are 0.169 and $0.181 \mathrm{nm},$ respectively. What is the length of
(a) the body diagonal?
(b) the side of the cell?

Eileen Sullivan

Eileen Sullivan

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Problem 57

Consider the sodium chloride unit cell shown in Figure 9.19. Looking only at the front face (five large Cl- ions, four small Na $^{+}$ ions),
(a) how many cubes share each of the $\mathrm{Na}^{+}$ ions in this face?
(b) how many cubes share each of the $\mathrm{Cl}^{-}$ ions in this face?

Aadit Sharma

Numerade Educator

Problem 58

Consider the CsCl unit shown in Figure 9.19. How many Cs $^{+}$ ions are there per unit cell? How many Cl- ions? (Note that each Cl- ion is shared by eight cubes.)

Eileen Sullivan

Eileen Sullivan

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Problem 59

A 1.25-L clean and dry flask is sealed. The air in the flask is at $27^{\circ} \mathrm{C}$ and $38 \%$ relative humidity. The flask is put in a cooler at $5^{\circ} \mathrm{C}$. How many grams of water will condense in the flask? (Use the table in Appendix 1 for the vapor pressure of water at various temperatures.)

Eileen Sullivan

Eileen Sullivan

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Problem 60

Vanadium crystallizes with a body-centered cubic unit cell. The volume of the unit cell is $0.0278 \mathrm{nm}^{3}$.
(a) What is the atomic radius of vanadium in $\mathrm{cm} ?$
(b) What is the volume of a single vanadium atom in $\mathrm{cm}^{3}$ ?
(c) What is the density of a single vanadium atom?
(d) In body-centered cubic unit cell packing, the fraction of empty space is $32.0 \%$. When this is factored in, what is the calculated
density of vanadium? (The experimental density of vanadium is $\left.5.8 \mathrm{~g} / \mathrm{cm}^{3} .\right)$

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 61

Consider a sealed flask with a movable piston that contains $5.25 \mathrm{~L}$ of $\mathrm{O}_{2}$ saturated with water vapor at $25^{\circ} \mathrm{C}$. The piston is depressed at constant temperature so that the gas is compressed to a volume of $2.00 \mathrm{~L}$. (Use the table in Appendix 1 for the vapor pressure of water at various temperatures.)
(a) What is the vapor pressure of water in the compressed gas mixture?
(b) How many grams of water condense when the gas mixture is compressed?

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 62

Packing efficiency is defined as the percent of the total volume of a solid occupied by (spherical) atoms. The formula is
packing efficiency $=\frac{\text { volume of the atom(s) in the cell }}{\text { volume of the cell }} \times 100$ The volume of one atom is $\frac{4}{3} \pi r^{3}$ and the volume of the cell is $s^{3},$ Calculate the packing efficiency of
(a) a simple cubic cell (1 atom/cell).
(b) a face-centered cubic cell ( 4 atoms/cell).
(c) a body-centered cubic cell ( 2 atoms/cell). Use Table 9.6 to relate $r$ to $s$.

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 63

Mercury is an extremely toxic substance. Inhalation of the vapor is just as dangerous as swallowing the liquid. How many milliliters of mercury will saturate a room that is $15 \times 12 \times 8.0 \mathrm{ft}$ with mercury vapor at $25^{\circ} \mathrm{C} ?$ The vapor pressure of $\mathrm{Hg}$ at $25^{\circ} \mathrm{C}$ is $0.00163 \mathrm{~mm} \mathrm{Hg}$ and its density is $13 \mathrm{~g} / \mathrm{ml}$

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 64

An experiment is performed to determine the vapor pressure of formic acid. A $30.0-\mathrm{L}$ volume of helium gas at $20.0^{\circ} \mathrm{C}$ is passed through $10.00 \mathrm{~g}$ of liquid formic acid (HCOOH) at $20.0^{\circ} \mathrm{C}$. After the experiment, $7.50 \mathrm{~g}$ of liquid formic acid remains. Assume that the helium gas becomes saturated with for-
mic acid vapor and the total gas volume and temperature remain constant. What is the vapor pressure of formic acid at $20.0^{\circ} \mathrm{C?}$

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 65

The normal boiling point for methyl hydrazine $\left(\mathrm{CH}_{3} \mathrm{~N}_{2} \mathrm{H}_{3}\right)$ is $87^{\circ} \mathrm{C}$. It has a vapor pressure of $37.0 \mathrm{~mm} \mathrm{Hg}$ at $20^{\circ} \mathrm{C}$. What is the concentration (in g/L) of methyl hydrazine if it saturates the air at $25^{\circ} \mathrm{C} ?$

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 66

Which of the following statements are true?
(a) The critical temperature must be reached to change liquid to gas.
(b) To melt a solid at constant pressure, the temperature must be above the triple point.
(c) $\mathrm{CHF}_{3}$ can be expected to have a higher boiling point than $\mathrm{CHCl}_{3}$ because CHF $_{3}$ has hydrogen bonding.
(d) One metal crystallizes in a body-centered cubic cell and another in a face-centered cubic cell of the same volume. The two atomic radii are related by the factor $\sqrt{1.5}$

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 67

Represent pictorially using ten molecules
(a) water freezing.
(b) water vaporizing.
(c) water being electrolyzed into hydrogen and oxygen.

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 68

In the blanks provided, answer the questions below, using LT (for is less than), GT (for is greater than), EQ (for is equal to), or MI (for more information required).
(a) The boiling point of $\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH}(\mathrm{MM}=60.0 \mathrm{~g} / \mathrm{mol})$
the
boiling point of $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{C}=\mathrm{O}(\mathrm{MM}=58.0 \mathrm{~g} / \mathrm{mol})$.
(b) The vapor pressure of $X$ is $250 \mathrm{~mm} \mathrm{Hg}$ at $57{ }^{\circ} \mathrm{C}$. Given a sealed flask at $57^{\circ} \mathrm{C}$ that contains only gas, the pressure in the flask $245 \mathrm{~mm} \mathrm{Hg}$
(c) The melting-point curve for Y tilts to the right of a straight line. The density of $\mathrm{Y}(l) \quad$ the density of $\mathrm{Y}(s)$
(d) The normal boiling point of $\mathrm{A}$ is $85^{\circ} \mathrm{C},$ while the normal boiling point of $\mathrm{B}$ is $45^{\circ} \mathrm{C}$. The vapor pressure of $\mathrm{A}$ at $85^{\circ} \mathrm{C}$ the vapor pressure of $\mathrm{B}$ at $45^{\circ} \mathrm{C}$.
(e) The triple point of $\mathrm{A}$ is $25 \mathrm{~mm} \mathrm{Hg}$ and $5^{\circ} \mathrm{C}$. The melting point of $\mathrm{A}$ $5^{\circ} \mathrm{C}$

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 69

Answer the questions below, by filling in the blanks with LT for is less than, GT for is greater than, EQ for is equal to, or MI for more information required.
(a) At $50^{\circ} \mathrm{C}$, benzene has a vapor pressure of $269 \mathrm{~mm} \mathrm{Hg}$. A flask that contains both benzene liquid and vapor at $50^{\circ} \mathrm{C}$ has a pressure $269 \mathrm{~mm} \mathrm{Hg}$
(b) Ether has a vapor pressure of $537 \mathrm{~mm} \mathrm{Hg}$ at $25^{\circ} \mathrm{C}$. A flask that contains only ether vapor at $37^{\circ} \mathrm{C}$ has a pressure $537 \mathrm{~mm} \mathrm{Hg}$
(c) The boiling point of $\mathrm{H}_{2} \mathrm{O}$ the boiling point of $\mathrm{C}_{3} \mathrm{H}_{8}$
(d) The energy required to vaporize liquid bromine the
energy required to decompose $\mathrm{Br}_{2}$ into $\mathrm{Br}$ atoms.
(e) The dispersion forces present in naphthalene, $\mathrm{C}_{10} \mathrm{H}_{8}$ the dispersion forces present in butane, $\mathrm{C}_{4} \mathrm{H}_{10}$

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 70

A liquid has a vapor pressure of $159 \mathrm{~mm} \mathrm{Hg}$ at $20^{\circ} \mathrm{C}$ and $165 \mathrm{~mm} \mathrm{Hg}$ at $30^{\circ} \mathrm{C}$. Different amounts of the liquid are added to three identical evacuated steel tanks kept at $20^{\circ} \mathrm{C}$. The tanks are all fitted with pressure gauges. For each part, write
$\mathbf{L} / \mathbf{G}$ if both liquid and gas are present. G if only gas is present. I if the situation is impossible.
(a) The pressure gauge in Flask I registers a pressure of $256 \mathrm{~mm} \mathrm{Hg}$.
(b) The pressure gauge in Flask II registers a pressure of $135 \mathrm{~mm} \mathrm{Hg}$.
(c) The pressure gauge in Flask III registers a pressure of $165 \mathrm{~mm} \mathrm{Hg}$ at $30^{\circ} \mathrm{C}$. The temperature is lowered to $20^{\circ} \mathrm{C}$, and the gauge registers a pressure of $159 \mathrm{~mm} \mathrm{Hg}$

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 71

Criticize or comment on each of the following statements.
(a) Vapor pressure remains constant regardless of volume.
(b) The only forces that affect boiling point are dispersion forces.
(c) The strength of the covalent bonds within a molecule has no effect
on the melting point of the molecular substance.
(d) A compound at its critical temperature is always a gas regardless of
pressure.

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 72

Differentiate between
(a) a covalent bond and a hydrogen bond.
(b) normal boiling point and a boiling point.
(c) the triple point and the critical point.
(d) a phase diagram and a vapor pressure curve.
(e) volume effect and temperature effect on vapor pressure.

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 73

. Four shiny solids are labeled $A, B, C,$ and $D .$ Given the following information about the solids, deduce the identity of $\mathrm{A}, \mathrm{B}, \mathrm{C},$ and $\mathrm{D}$.
(1) The solids are a graphite rod, a silver bar, a lump of "fool's gold" (iron sulfide), and iodine crystals.
(2) $\mathrm{B}, \mathrm{C},$ and $\mathrm{D}$ are insoluble in water. $\mathrm{A}$ is slightly soluble.
(3) Only C can be hammered into a sheet.
(4) $\mathrm{C}$ and $\mathrm{D}$ conduct electricity as solids; $\mathrm{B}$ conducts when melted; $\mathrm{A}$ does not conduct as a solid, melted, or dissolved in water.

Nicole Smina

Numerade Educator

Problem 74

Consider the vapor pressure curves of molecules $A, B,$ and $C$ shown below.
(a) Which compound $(A, B,$ or $C)$ has the weakest forces between molecules?
(b) Which compound $(A, B,$ or $C)$ has a normal boiling point at about $15^{\circ} \mathrm{C} ?$
(c) At what temperature will $\mathrm{B}$ boil if the atmospheric pressure is $500 \mathrm{~mm} \mathrm{Hg} ?$
(d) At $25^{\circ} \mathrm{C}$ and $400 \mathrm{~mm} \mathrm{Hg},$ what is the physical state of $\mathrm{A} ?$
(e) At what pressure will C boil at $40^{\circ} \mathrm{C?}$

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 75

The following data are given for $\mathrm{CCl}_{4}$ :
normal melting point $=-23^{\circ} \mathrm{C}$
normal boiling point $=77^{\circ} \mathrm{C}$ density of liquid $=1.59 \mathrm{~g} / \mathrm{mL}$
vapor pressure at $25^{\circ} \mathrm{C}=110 \mathrm{~mm} \mathrm{Hg}$
How much heat is required to vaporize $20.0 \mathrm{~L}$ of $\mathrm{CCl}_{4}$ at its normal boiling point?

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 76

Iron crystallizes in a body-centered unit cell. Its atomic radius is $0.124 \mathrm{nm} .$ Its density is $7.86 \mathrm{~g} / \mathrm{cm}^{3}$. Using this information, estimate Avogadro's number.

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 77

A flask with a volume of $10.0 \mathrm{~L}$ contains $0.400 \mathrm{~g}$ of hydrogen gas and $3.20 \mathrm{~g}$ of oxygen gas. The mixture is ignited and the reaction $$ 2 \mathrm{H}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O} $$ goes to completion. The mixture is cooled to $27^{\circ} \mathrm{C}$. Assuming $100 \%$ yield,
(a) What physical state(s) of water is (are) present in the flask?
(b) What is the final pressure in the flask?
(c) What is the pressure in the flask if $3.2 \mathrm{~g}$ of each gas is used?

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 78

Trichloroethane, $\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{Cl}_{3}$, is the active ingredient in aerosols that claim. to stain-proof men's ties. Trichloroethane has a vapor pressure of $100.0 \mathrm{~mm} \mathrm{Hg}$ at $20.0^{\circ} \mathrm{C}$ and boils at $74.1^{\circ} \mathrm{C}$. An uncovered cup ( $\frac{1}{2}$ pint) of trichloroethane $(d=1.325 \mathrm{~g} / \mathrm{mL})$ is kept in an $18-\mathrm{ft}^{3}$ refrigerator at $39^{\circ} \mathrm{F}$. What percentage (by mass) of the trichloroethane is left as a liquid when equilibrium is established?

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 79

It has been suggested that the pressure exerted on a skate blade is sufficient to melt the ice beneath it and form a thin film of water, which makes it easier for the blade to slide over the ice. Assume that a skater weighs $120 \mathrm{lb}$ and the blade has an area of 0.10 in $^{2}$. Calculate the pressure exerted on the blade $\left(1 \mathrm{~atm}=15 \mathrm{lb} / \mathrm{in}^{2}\right)$. From information in the text, calculate the decrease in melting point at this pressure. Comment on the plausibility of this explanation and suggest another mechanism by which the water film might be formed.

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 80

As shown in Figure $9.18, \mathrm{Li}^{+}$ ions fit into a closely packed array of $\mathrm{Cl}^{-}$ ions, but $\mathrm{Na}^{+}$ ions do not. What is the value of the $r_{\text {cation }} / r_{\text {anion }}$ ratio at which a cation just fits into a structure of this type?

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 81

When the temperature drops from $20^{\circ} \mathrm{C}$ to $10^{\circ} \mathrm{C}$, the pressure of a cylinder of compressed $\mathrm{N}_{2}$ drops by $3.4 \%$. The same temperature change decreases the pressure of a propane $\left(\mathrm{C}_{3} \mathrm{H}_{8}\right)$ cylinder by $42 \%$. Explain the difference in behavior.

Nicole Smina

Numerade Educator