Problem 2

Explain how solid naphthalene in mothballs

is distributed evenly through clothes in a

drawer.

Theodore D.

Numerade Educator

Problem 4

Carbon tetrachloride, $\mathrm{CCl}_{4},$ is nonpolar.

What forces hold the molecules together?

Theodore D.

Numerade Educator

Problem 9

Compare the arrangement and movement

of particles in the solid, liquid, and gas states

of matter.

Check back soon!

Problem 11

A small drop of water assumes an almost

spherical form on a Teflon surface.

Explain why.

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Problem 12

What is happening when water is heated

from $25^{\circ} \mathrm{C}$ to $155^{\circ} \mathrm{C}$ ?

Theodore D.

Numerade Educator

Problem 14

Contrast ionic and molecular substances in

terms of the types of attractive forces that

govern their behavior.

Theodore D.

Numerade Educator

Problem 15

Is the melting point of CaCl_ higher than

that of $\mathrm{NaCl}$ or lower? Explain your answer.

Check back soon!

Problem 16

A fellow student says, "All substances

experience London dispersion forces of

attraction between particles." Is this

statement true? Explain your answer.

Theodore D.

Numerade Educator

Problem 17

Which has larger London dispersion forces

between its molecules, CF $_{4}$ or $\mathrm{CCl}_{4}$ ?

Check back soon!

Problem 18

Of the three forces, ionic, dipole-dipole, and

London dispersion forces, which is the

strongest?

Theodore D.

Numerade Educator

Problem 19

Why does ice float in water even though

most solids sink in the pure liquid?

Check back soon!

Problem 20

Why does $\mathrm{CBr}_{4}$ boil at a higher temperature

than $\mathrm{CCl}_{4}$ does?

Theodore D.

Numerade Educator

Problem 21

The molar enthalpy of fusion of water is

6.009 $\mathrm{kJ} / \mathrm{mol}$ at $0^{\circ} \mathrm{C}$ . Explain what this

statement means.

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Problem 22

Why is the molar enthalpy of vaporization

of a substance much higher than the molar

enthalpy of fusion?

Theodore D.

Numerade Educator

Problem 23

How do you calculate the entropy change

during a change of state at equilibrium?

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Problem 24

Why is the entropy of a substance higher in

the liquid state than in the solid state?

Theodore D.

Numerade Educator

Problem 25

At $100^{\circ} \mathrm{C},$ the enthalpy change for condensa-

tion of water vapor to liquid is negative. Is

the entropy change positive, or is it negative?

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Problem 26

$\Delta H$ for a process is positive, and $\Delta S$ is

negative. What can you conclude about

the process?

Theodore D.

Numerade Educator

Problem 27

Explain why liquid water at 273.0 $\mathrm{K}$ will not

melt in terms of Gibbs energy.

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Problem 28

What thermodynamic values do you need

to know to calculate a substance's melting

point?

Theodore D.

Numerade Educator

Problem 30

How does pressure affect changes between

the liquid and vapor states?

Theodore D.

Numerade Educator

Problem 31

You have sweetened iced tea with sugar,

and ice cubes are present. How many phases

are present?

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Problem 32

The term vapor pressure almost always

means the equilibrium vapor pressure. What

physical arrangement is needed to measure

vapor pressure?

Theodore D.

Numerade Educator

Problem 33

What is meant by the statement that a liquid

and its vapor in a closed container are in a

state of equilibrium?

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Problem 34

As the temperature of a liquid increases,

what happens to the vapor pressure?

Theodore D.

Numerade Educator

Problem 35

Use the above graph of the vapor pressure

of water versus temperature to answer the

following questions.

\begin{equation}

\begin{array}{l}{\text { a. At what point(s) does water boil at }} \\ {\text { standard atmospheric pressure? }} \\ {\text { b. At what point(s) is water only in the }} \\ {\text { liquid phase? }}\end{array}

\end{equation}

\begin{equation}

\begin{array}{l}{\text { c. At what point(s) is water only in the }} \\ {\text { vapor phase? }} \\ {\text { d. At what point(s) is liquid water in }} \\ {\text { equilibrium with water vapor? }}\end{array}

\end{equation}

Check back soon!

Problem 37

\begin{equation}

\begin{array}{l}{\text { The enthalpy of fusion of chlorine, } \mathrm{Cl}_{2}, \text { is }} \\ {6.40 \mathrm{kJ} / \mathrm{mol}, \text { and the entropy of fusion is }} \\ {37.2 \mathrm{J} / \mathrm{mol} \cdot \mathrm{K} \text { . }}\end{array}

\end{equation}

Check back soon!

Problem 38

The enthalpy of fusion of sulfur trioxide is

8.60 $\mathrm{kJ} / \mathrm{mol}$ , and the entropy of fusion is

29.7 $\mathrm{J} / \mathrm{mol} \cdot \mathrm{K}$

Theodore D.

Numerade Educator

Problem 39

The enthalpy of vaporization of butane,

$\mathrm{C}_{4} \mathrm{H}_{10},$ is 22.44 $\mathrm{kJ} / \mathrm{mol}$ , and the entropy of

vaporization is 82.2 $\mathrm{J} / \mathrm{mol} \cdot \mathrm{K}$ .

Check back soon!

Problem 40

$\Delta H_{v a p}$ for silicon tetrachloride is

$28.7 \mathrm{kJ} / \mathrm{mol},$ and $\Delta S_{\text {vap}}$ is 86.7 $\mathrm{J} / \mathrm{mol} \cdot \mathrm{K}$

Theodore D.

Numerade Educator

Problem 41

The critical point for krypton is at $-64^{\circ} \mathrm{C}$

and a pressure of $5.5 \times 10^{3} \mathrm{kP}$ . The triple

point is at $-157.4^{\circ} \mathrm{C}$ and a pressure of

$73.2 \mathrm{kPa} . \mathrm{At}-172^{\circ} \mathrm{C}$ the vapor pressure is

13 $\mathrm{kPa}$ . The normal boiling point is

$-152^{\circ} \mathrm{C} .$ Sketch the phase diagram.

Check back soon!

Problem 42

The critical point for carbon tetrachloride is

at $283^{\circ} \mathrm{C}$ and $4.5 \times 10^{3}$ kPa. The triple point is

at $-87.0^{\circ} \mathrm{C}$ and 28.9 $\mathrm{kPa}$ . The normal boiling

point is $76.7^{\circ} \mathrm{C}$ . Sketch the phase diagram.

Theodore D.

Numerade Educator

Problem 43

Calculate the melting point of acetic acid at

standard pressure. The enthalpy of fusion of

acetic acid is $11.54 \mathrm{kJ} / \mathrm{mol},$ and the entropy

of fusion is 39.8 $\mathrm{J} / \mathrm{mol} \cdot \mathrm{K}$ .

Check back soon!

Problem 44

$\Delta H_{v a p}$ for gold is $324 \mathrm{kJ} / \mathrm{mol},$ and $\Delta S_{\text {vap}}$ is

103.5 $\mathrm{J} / \mathrm{mol} \cdot \mathrm{K}$ . Calculate the boiling point

of gold.

Theodore D.

Numerade Educator

Problem 45

The critical point for HBr is at $90^{\circ} \mathrm{C}$ and

$8.56 \times 10^{3}$ kPa. The triple point is at $-87.0^{\circ} \mathrm{C}$

and 29 $\mathrm{kP}$ . The normal boiling point is

$-66.5^{\circ} \mathrm{C} .$ Sketch the phase diagram.

Check back soon!

Problem 46

How can water be made to evaporate rap-

idly at room temperature?

Theodore D.

Numerade Educator

Problem 48

Which would have the higher boiling point:

chloroform, $\mathrm{CHCl}_{3},$ or bromoform, $\mathrm{CHBr}_{3}$ ?

Theodore D.

Numerade Educator

Problem 49

You know that the enthalpy change for

vaporizing water is $\Delta H_{v a p}=H_{g a s}-H_{l i q}$

What is the Gibbs energy change for this

process?

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Problem 50

Explain why steam produces much more

severe burns than the same amount of boiling water does.

Theodore D.

Numerade Educator

Problem 51

Chloroethane $\left(T_{b p}=-13^{\circ} \mathrm{C}\right)$ has been used

as a local anesthetic. When the liquid is

sprayed onto the skin, it cools the skin

enough to freeze and numb the skin.

Explain the cooling effect of this liquid.

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Problem 52

Is it possible to have only liquid water present in a container at $0.00^{\circ} \mathrm{C}$ ? Explain.

Theodore D.

Numerade Educator

Problem 53

Consider a system composed of water

vapor and liquid at equilibrium at $100^{\circ} \mathrm{C}$ .

Do the molecules of $\mathrm{H}_{2} \mathrm{O}$ in the vapor have

more kinetic energy than molecules in the

liquid do? Explain.

Check back soon!

Problem 54

Look at the phase diagram for carbon

dioxide. How can $\mathrm{CO}_{2}$ be made to boil?

Theodore D.

Numerade Educator

Problem 55

Liquid crystals are substances that have

properties of both liquids and crystals.

Write a report on these substances and

their various uses.

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Problem 56

Some liquids lose all viscosity when cooled

to extremely low temperatures - a phenomenon called superfluidity. Find out more about

the properties of superfluid substances.

Theodore D.

Numerade Educator

Problem 57

Many scientists think that more than 99$\%$

of the known matter in the universe is

made of a fourth state of matter called

plasma. Research plasmas, and report your

findings to the class.

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Problem 58

Prepare a report about the adjustments that

must be made when cooking and baking at

high elevations. Collect instructions for high-

elevation adjustments from packages of prepared food mixes. Explain why changes must

be made in recipes that will be prepared at

high elevations. Check your library for cook-books that contain information about food

preparation at high elevations.

Theodore D.

Numerade Educator

Problem 59

Use the following terms to create a concept

map: boiling point, liquids, vapor pressure,

gases, melting point, states, and equilibrium.

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Problem 62

Give the coordinates for a point at

which liquid water is in equilibrium

with vapor.

Theodore D.

Numerade Educator

Problem 65

What will happen if the vapor at

point $D$ is cooled at constant pressure?

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Problem 66

Calculating Vapor Pressure by Using a Table

The graphing calculator can run a program

that calculates a table for the vapor pressure

in atmospheres at different temperatures (K)

given the number of moles of a gas and the

volume of the gas (V). Given a 0.50 mol gas

sample with a volume of $10 \mathrm{L},$ you can calculate the pressure at 290 $\mathrm{K}$ by using a table.

Use this program to make the table. Next,

use the table to perform the calculations.

Go to Appendix C. If you are using a TI- -83

Plus, you can download the program

VAPOR and data and run the application as

directed. If you are using another calculator,

your teacher will provide you with key-

strokes and data sets to use. After you have

run the program, answer the questions.

a. What is the pressure for 1.3 mol of a gas

with a volume of 8.0 $\mathrm{L}$ and a temperature

of 320 $\mathrm{K} ?$

b. What is the pressure for 1.5 mol of a gas

with a volume of 10.0 $\mathrm{L}$ and a temperature of 340 $\mathrm{K} ?$

Two gases are measured at 300 $\mathrm{K}$ . One

has an amount of 1.3 $\mathrm{mol}$ and a volume of

$7.5 \mathrm{L},$ and the other has an amount of

0.5 $\mathrm{mol}$ and a volume of 10.0 $\mathrm{L} .$ Which

gas has the lesser pressure?

Theodore D.

Numerade Educator