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Holt Chemistry

R.Thomas Myers, Keith Oldham,Savatore Tocci

Chapter 12

Gases - all with Video Answers

Educators


Chapter Questions

01:14

Problem 1

What is the definition of pressure?

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00:55

Problem 2

What is a newton?

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05:31

Problem 3

Write a paragraph that describes
how the kinetic-molecular theory
explains the following properties of a gas: fluidity, compressibility, and pressure.

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01:21

Problem 4

How do pascals relate to newtons?

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01:30

Problem 5

What relationship does Boyle's law express?

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01:02

Problem 6

What relationship does Charles's law
express?

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01:04

Problem 7

What relationship does Gay-Lussac's law
express?

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02:32

Problem 8

What gas law combines the basic gas laws?

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02:50

Problem 9

What are two characteristics of an ideal gas?

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02:20

Problem 10

Describe in your own words the process of
diffusion.

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01:45

Problem 11

How does wind illustrate that gases are
fluids?

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02:56

Problem 12

Using air, water, and a syringe, how can you
show the difference in compressibility of
liquids and gases?

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02:43

Problem 13

When you drive a car on hot roads, the
oressure in the tires increases. Explain.

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01:45

Problem 14

As you put more air in a car tire, the
pressure increases. Explain.

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03:16

Problem 15

When you expand your lungs, air flows in.
Explain.

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01:42

Problem 16

Even when there is air in bicycle tires, you
can still push down on the handle of the
pump rather easily. Explain.

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01:39

Problem 17

When you put air in a completely flat
bicycle tire, the entire tire expands. Explain

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02:24

Problem 18

What assumptions does the kinetic-molecular
theory make about the nature of a gas?

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02:01

Problem 19

How does the average kinetic energy of a
gas relate to its temperature?

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02:14

Problem 20

How are the volume and pressure of a gas
related, if its temperature is kept constant?

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02:20

Problem 21

Explain why pressure increases as a gas is
compressed into a smaller volume.

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01:56

Problem 22

How are the absolute temperature and volume of a gas related, at constant pressure?

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03:54

Problem 23

Explain Charles's law in terms of the
kinetic-molecular theory.

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03:00

Problem 24

How is a gas's pressure related to its
temperature, at constant volume?

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03:43

Problem 25

Explain Gay-Lussac's law in terms of the
kinetic-molecular theory.

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01:39

Problem 26

What does Avogadro's law state about the
relationship between gas volumes and
amounts in moles?

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02:23

Problem 27

When using the ideal gas law, what is the
proportionality constant, and in what units
is it usually expressed?

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03:07

Problem 28

Ammonia, $\mathrm{NH}_{3},$ and alcohol, $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O},$ are
released together across a room. Which will
you smell first?

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02:36

Problem 29

How can Gay-Lussac's law of combining
volumes be used to deduce chemical
formulas?

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01:33

Problem 30

Write the equation that expresses Dalton's
law of partial pressures.

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01:36

Problem 31

The standard pressure at sea level is
101325 pascals. What force is being exerted
on each square meter of Earth's surface?

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02:00

Problem 32

The vapor pressure of hydrogen peroxide is
100.0 torr at $97.9^{\circ} \mathrm{C} .$ What is this pressure in
$\mathrm{kPa}$ ?

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02:16

Problem 33

The gauge pressure in a tire is 28 psi, which
adds to atmospheric pressure of 14.0 psi.
What is the internal tire pressure in kPa?

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01:41

Problem 34

The weather bureau reports the atmospheric
pressure as 925 millibars. What is this pres-
sure in kPa?

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02:09

Problem 35

A gas sample has a volume of 125 $\mathrm{mL}$ at
91.0 $\mathrm{kPa}$ . What will its volume be at 101 $\mathrm{kPa}$ ?

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01:56

Problem 36

A gas sample has a volume of 125 $\mathrm{mL}$ at
91.0 $\mathrm{kPa}$ . What will its volume be at 101 $\mathrm{kPa}$ ?

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02:49

Problem 37

A diver at a depth of $1.0 \times 10^{2} \mathrm{m},$ where the
pressure is 11.0 atm, releases a bubble with a
volume of 100.0 $\mathrm{mL}$ . What is the volume of
the bubble when it reaches the surface?
Assume a pressure of 1.00 atm at the surface.

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02:58

Problem 38

A diver at a depth of $1.0 \times 10^{2} \mathrm{m},$ where the
pressure is 11.0 atm, releases a bubble with a
volume of 100.0 $\mathrm{mL}$ . What is the volume of
the bubble when it reaches the surface?
Assume a pressure of 1.00 atm at the surface.

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02:29

Problem 39

The pressure on a 240.0 $\mathrm{mL}$ sample of
helium gas is increased from 0.428 atm to
1.55 atm. What is the new volume, assuming
constant temperature?

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02:44

Problem 40

A sample of air with volume $6.6 \times 10^{7} \mathrm{L}$
changes pressure from 99.4 kPa to 88.8 $\mathrm{kPa}$ .
Assuming constant temperature, what is the
new volume?

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02:20

Problem 41

Use Charles's law to solve for the missing
value in the following. $V_{1}=80.0 \mathrm{mL}, T_{1}=$
$27^{\circ} \mathrm{C}, T_{2}=77^{\circ} \mathrm{C}, V_{2}=?$

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02:04

Problem 42

A balloon filled with helium has a volume
of 2.30 L on a warm day at 311 K. It is
brought into an air-conditioned room where
the temperature is 295 $\mathrm{K}$ . What is its new
volume?

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02:16

Problem 43

The balloon in item 42 is dipped into liquid
nitrogen at $-196^{\circ} \mathrm{C}$ . What is its new volume?

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03:41

Problem 44

A gas at $65^{\circ} \mathrm{C}$ occupies 4.22 $\mathrm{L} .$ At what
Celsius temperature will the volume be
$3.87 \mathrm{L},$ at the same pressure?

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02:49

Problem 45

A person breathes 2.6 $\mathrm{L}$ of air at $-11^{\circ} \mathrm{C}$ into
her lungs, where it is warmed to $37^{\circ} .$ What is
its new volume?

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02:40

Problem 46

A scientist warms 26 $\mathrm{mL}$ of gas at $0.0^{\circ} \mathrm{C}$
until its volume is 32 $\mathrm{mL} .$ What is its new
temperature in degrees Celsius?

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02:13

Problem 47

Use Gay-Lussac's law to solve for the
unknown. $P_{1}=111 \mathrm{kPa}, T_{1}=273 \mathrm{K}, 7$
$373 \mathrm{K}, P_{2}=?$

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02:39

Problem 48

A sample of hydrogen exerts a pressure of
0.329 atm at $47^{\circ} \mathrm{C}$ . What will the pressure bo
at $77^{\circ} \mathrm{C},$ assuming constant volume?

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02:38

Problem 49

A sample of hydrogen exerts a pressure of
0.329 atm at $47^{\circ} \mathrm{C}$ . What will the pressure bo
at $77^{\circ} \mathrm{C},$ assuming constant volume?

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03:03

Problem 50

The pressure inside a tire is 39 psi at $20^{\circ} \mathrm{C}$ .
What will the pressure be after the tire is
driven at high speed on a hot highway,
when the temperature in the tire is $48^{\circ} \mathrm{C}$ ?

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02:55

Problem 51

A tank of oxygen for welding is at $31^{\circ} \mathrm{C}$
and 11 atm. What is the pressure when it
is taken to the South Pole, where the
temperature is $-41^{\circ} \mathrm{C} ?$

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02:50

Problem 52

How many moles of argon are there in
$20.0 \mathrm{L},$ at $25^{\circ} \mathrm{C}$ and 96.8 $\mathrm{kPa}$ ?

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02:57

Problem 53

How many moles of air are in 1.00 $\mathrm{L}$
at $-23^{\circ} \mathrm{C}$ and 101 $\mathrm{kPa}$ ?

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04:07

Problem 54

A 4.44 L container holds 15.4 g of oxygen at
$22.55^{\circ} \mathrm{C} .$ What is the pressure?

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02:58

Problem 55

A polyethylene plastic weather balloon
contains 65 . of helium, which is at $20.0^{\circ} \mathrm{C}$
and 94.0 $\mathrm{kP}$ . How many moles of helium
are in the balloon?

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02:55

Problem 56

What will be the volume of the balloon in
item 56 in the stratosphere at $-61^{\circ} \mathrm{C}$ and
$1.1 \times 10^{3} \mathrm{Pa}$ ?

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03:07

Problem 57

An unknown gas effuses at a speed one-
quarter of that of helium. What is the molar
mass of the unknown gas? It is either sulfur
dioxide or sulfur trioxide. Which gas is it?

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02:42

Problem 58

An unknown gas effuses at one half the
speed of oxygen. What is the molar mass of
the unknown? It is either HBr or HI. Which
gas is it?

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02:38

Problem 59

Oxygen molecules have an average speed
of $4.80 \times 10^{2} \mathrm{m} / \mathrm{s}$ at $25^{\circ} \mathrm{C}$ . What is the
average speed of $\mathrm{H}_{2}$ molecules at the same
temperature?

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04:40

Problem 60

How many liters of hydrogen gas can be
produced at 300.0 $\mathrm{K}$ and 104 $\mathrm{kPa}$ if 20.0 $\mathrm{g}$
of sodium metal is reacted with water
according to the following equation?
$$2 \mathrm{Na}(s)+2 \mathrm{H}_{2} \mathrm{O}(l) \rightarrow 2 \mathrm{NaOH}(a q)+\mathrm{H}_{2}(g)$$

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04:58

Problem 61

Magnesium will burn in oxygen to form
magnesium oxide as represented by the
following equation.
$$2 \mathrm{Mg}(s)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{MgO}(s)$$
What mass of magnesium will react
with 500.0 $\mathrm{mL}$ of oxygen at $150.0^{\circ} \mathrm{C}$ and
70.0 $\mathrm{kPa}$ ?

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05:13

Problem 62

Suppose a certain automobile engine has a
cylinder with a volume of 500.0 $\mathrm{mL}$ that is
filled with air $(21 \%$ oxygen) at a tempera-
ture of $55^{\circ} \mathrm{C}$ and a pressure of 101.0 $\mathrm{kPa}$ .
What mass of octane must be injected to
react with all of the oxygen in the cylinder?
$$2 \mathrm{C}_{8} \mathrm{H}_{18}(l)+25 \mathrm{O}_{2}(g) \rightarrow 16 \mathrm{CO}_{2}(g)+18 \mathrm{H}_{2} \mathrm{O}(g)$$

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04:35

Problem 63

Methanol, $\mathrm{CH}_{3} \mathrm{OH},$ is made by using a
catalyst to react carbon monoxide with
hydrogen at high temperature and pressure.
Assuming that 450.0 $\mathrm{mL}$ of $\mathrm{CO}$ and 825 $\mathrm{mL}$
of $\mathrm{H}_{2}$ are allowed to react, answer the
following questions. (Hint: First write the balanced chemical equation for this reaction.)
a. Which reactant is in excess?
b. How much of that reactant remains
when the reaction is complete?
c. What volume of $\mathrm{CH}_{3} \mathrm{OH}(g)$ is produced?

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03:18

Problem 64

What volume of oxygen, measured at $27^{\circ} \mathrm{C}$
and 101.325 $\mathrm{kPa}$ , is needed for the combus-
tion of 1.11 $\mathrm{kg}$ of coal? (Assume coal is
100$\%$ carbon.)
$$\mathrm{C}(s)+\mathrm{O}_{2}(g) \rightarrow \mathrm{CO}_{2}(g$$

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03:21

Problem 65

How many liters of hydrogen are obtained
from the reaction of 4.00 g calcium with
excess water, at $37^{\circ} \mathrm{C}$ and 0.962 atm?

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03:52

Problem 66

How many grams of carbon dioxide are
contained in 1.000 L of the gas, at $25.0^{\circ} \mathrm{C}$
and 101.325 $\mathrm{kPa}$ ? What is the density of the
gas at these conditions? What would the
density of oxygen be at these conditions?

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01:27

Problem 67

Below is a diagram showing the effects of
pressure on a column of mercury and on a
column of water. Which system is under a
higher pressure? Explain your choice.

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04:09

Problem 68

Solid LiOH can be used in spacecraft to
remove $\mathrm{CO}_{2}$ from the air.
$$2 \mathrm{LiOH}(s)+\mathrm{CO}_{2}(g) \rightarrow \mathrm{Li}_{2} \mathrm{CO}_{3}(s)+\mathrm{H}_{2} \mathrm{O}(l)$$
What mass of LiOH must be used to absorb
the carbon dioxide that exerts a partial
pressure of 5.0 $\mathrm{kPa}$ at $15^{\circ} \mathrm{C}$ in a spacecraft
with volume of $8.0 \times 10^{4} \mathrm{L} ?$

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02:52

Problem 69

How many grams of oxygen gas must be in
a 10.0 L container to exert a pressure of
97.0 kPa at a temperature of $25^{\circ} \mathrm{C} ?$

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02:39

Problem 70

Explain in terms of the kinetic-molecular
theory why increasing the temperature of
a gas at constant volume increases the
pressure of the gas.

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01:58

Problem 71

Above $100^{\circ} \mathrm{C}$ and at constant pressure, two
volumes of hydrogen react with one volume
of oxygen to form two volumes of gaseous
water. Set up a diagram for this reaction
that is similar to Figure $19,$ and that shows
how the molecular formulas for oxygen and
water can be determined.

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01:58

Problem 72

Clean rooms, used for sterile biological
research, are sealed tightly and operate
under high air pressure. Explain why.

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01:42

Problem 73

The partial pressure of oxygen in the air is
0.21 atm at sea level, where the total pressure is 1.00 atm. What is the partial pressure
of oxygen when this air rises to where the
total pressure is 0.86 atm?

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03:22

Problem 74

You have a 1 $\mathrm{L}$ container of a gas at $20^{\circ} \mathrm{C}$
and 1 atm. Without opening the container,
how could you tell whether the gas is
chlorine or fluorine?

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01:38

Problem 75

Gas companies often store their fuel sup-
plies in liquid form and in large storage
tanks. Liquid nitrogen is used to keep the
temperature low enough for the fuel to
remain condensed in liquid form. Although
continuous cooling is expensive, storing a
condensed fuel is more economical than
storing the fuel as gas. Suggest a reason that
storing a liquid is more economical than
storing a gas.

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01:12

Problem 76

How would the shape of a curve showing
the kinetic-energy distribution of gas
molecules at $50^{\circ} \mathrm{C}$ compare with the blue
and red curves in Figure 8 ?

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01:30

Problem 77

The air pressure of car tires should be
checked regularly for safety reasons and to
prevent uneven tire wear. Find out the units
of measurement on a typical tire gauge, and
determine how gauge pressure relates to
atmospheric pressure.

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01:54

Problem 78

Find a local hot-air balloon group, and dis-
cuss with group members how they use the
gas laws to fly their balloons. The group may
be willing to give a demonstration. Report
your experience to the class.

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06:05

Problem 79

Use the following terms to create a concept
map: amount in moles, ideal gas law, pres-
sure, temperature, and volume.

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00:31

Problem 80

What variable decreases as you go
down the $y$ -axis of the graph?

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00:47

Problem 81

What is the volume of the gas at a
pressure of 150 $\mathrm{kPa}$ ?

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00:44

Problem 82

What is the pressure of the gas at a
volume of 0.200 $\mathrm{L} ?$

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00:54

Problem 83

Describe in your own words the
relationship this graph illustrates.

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01:34

Problem 84

List the values of volume and
pressure that correspond to any
two points on the graph, and show
why they demonstrate Bovle's law

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01:45

Problem 85

Explain why you feel resistance if
you try to compress a sample of
gas inside a plugged syringe.

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03:57

Problem 86

Calculating Pressure Using the Ideal Gas Law
The graphing calculator can run a program
that calculates the pressure in atmospheres,
given the number of moles of a gas (n)
volume $(V),$ and temperature $(T) .$

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