Principles of Chemistry: A Molecular Approach

Nivaldo J. Tro

Chapter 5

Gases - all with Video Answers

Educators

Chapter Questions

Problem 1

The pressure in Denver, Colorado (elevation $5280 \mathrm{ft}$, averages about $24.9$ in $\mathrm{Hg}$. Convert this pressure to
a. atm
b. $\mathrm{mmHg}$
c. psi
d. $\overline{P a}$

David Collins

David Collins

Numerade Educator

Problem 2

The pressure on top of Mt. Everest averages about $235 \mathrm{mmHg}$. Convert this pressure to
a. torr
b. $\mathrm{psi}$
c. in $\mathrm{Hg}$
d. atm

Nicole Mabante

Numerade Educator

Problem 3

The North American record for highest recorded barometric pressure is $31.85$ in $\mathrm{Hg}$, set in 1989 in Northway, Alaska. Convert this pressure to
a. $\mathrm{mmHg}$
b. atm
c. torr
d. kPa (kilopascals)

Dalton Hilovsky

Dalton Hilovsky

Numerade Educator

Problem 4

The world record for lowest pressure barometric (at sea level) was $652.5 \mathrm{mmHg}$ recorded inside Typhoon Tip on October 12,1979, in the Western Pacific Ocean. Convert this pressure to
$a$ torr
b. atm
c. in $\mathrm{Hg}$
d. psi

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 5

A sample of gas has an initial volume of $2.8 \mathrm{~L}$ at a pressure of 755 $\mathrm{mmHg}$. If the volume of the gas is increased to $3.7 \mathrm{~L}$, what will the pressure be?

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 6

A sample of gas has an initial volume of $32.6 \mathrm{~L}$ at a pressure of $1.3$ atm. If the sample is compressed to a volume of $13.8 \mathrm{~L}$, what will its pressure be?

ES

Eugene Schneider

University of Minnesota - Twin Cities

Problem 7

A $48.3-\mathrm{mL}$ sample of gas in a cylinder is warmed from $22{ }^{\circ} \mathrm{C}$ to $87{ }^{\circ} \mathrm{C}$. What is its volume at the final temperature?

Dalton Hilovsky

Dalton Hilovsky

Numerade Educator

Problem 8

A syringe containing $1.55 \mathrm{~mL}$ of oxygen gas is cooled from $95.3^{\circ} \mathrm{C}$ to $0.0{ }^{\circ} \mathrm{C}$. What is the final volume of axygen gas?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 9

A balloon contains $0.128$ mol of gas and has a volume of $2.76 \mathrm{~L}$. If an additional $0.073$ mol of gas is added to the balloon (at the same temperature and pressure), what will its final volume be?

Madeline Currie

Madeline Currie

Numerade Educator

Problem 10

A cylinder with a moveable piston contains $0.87 \mathrm{~mol}$ of gas and has a volume of $334 \mathrm{~mL}$. What will its volume be if an additional $0.22$ mol of gas is added to the cylinder? (Assume constant temperature and pressure.)

Madeline Currie

Madeline Currie

Numerade Educator

Problem 11

What is the volume occupied by $0.118$ mol of helium gas at a pressure of $0.97$ atm and a temperature of $305 \mathrm{~K} ?$

Madeline Currie

Madeline Currie

Numerade Educator

Problem 12

What is the pressure in a $10.0$ -L cylinder filled with $0.448$ mol of nitrogen gas at a temperature of $315 \mathrm{~K} ?$

Kevin Chimex

Numerade Educator

Problem 13

A cylinder contains $28.5 \mathrm{~L}$ of oxygen gas at a pressure of $1.8 \mathrm{~atm}$ and a temperature of $298 \mathrm{~K}$. How much gas (in moles) is in the cylinder?

Sisi Gao

Numerade Educator

Problem 14

What is the temperature of $0.52$ mol of gas at a pressure of $1.3$ $\mathrm{atm}$ and a volume of $11.8 \mathrm{~L} ?$

ES

Eugene Schneider

University of Minnesota - Twin Cities

Problem 15

An automobile tire has a maximum rating of $38.0$ psi (gauge pressure). The tire is inflated (while cold) to a volume of $11.8 \mathrm{~L}$ and $\mathrm{a}$ gauge pressure of $36.0$ psiat a temperature of $12.0^{\circ} \mathrm{C}$. While driving on a hot day, the tire warms to $65.0^{\circ} \mathrm{C}$ and its volume expands to $12.2 \mathrm{~L}$. Does the pressure in the tire exceed its maximum rating? (Note: The gauge pressure is the difference between the total pressure and atmospheric pressure. In this case, assume that atmospheric pressure is $14.7$ psi.)

Kevin Chimex

Numerade Educator

Problem 16

A weather balloon is inflated to a volume of $28.5 \mathrm{~L}$ at a pressure of $748 \mathrm{mmHg}$ and a temperature of $28.0^{\circ} \mathrm{C}$. The balloon rises in the atmosphere to an altitude of approximately 25,000 feet, where the pressure is $385 \mathrm{mmHg}$ and the temperature is $-15.0{ }^{\circ} \mathrm{C}$. Assuming the balloon can freely expand, calculate the volume of the balloon at this altitude.

Dalton Hilovsky

Dalton Hilovsky

Numerade Educator

Problem 17

A piece of dry ice (solid carbon dioxide) with a mass of $28.8 \mathrm{~g}$ is allowed to sublime (convert from solid to gas) into a large balloon. Assuming that all of the carbon dioxide ends up in the balloon, what will be the volume of the balloon at a temperature of $22{ }^{\circ} \mathrm{C}$ and a pressure of $742 \mathrm{mmHg} ?$

Nicole Mabante

Numerade Educator

Problem 18

A $1.0$ - L container of liquid nitrogen is kept in a closet measuring $1.0 \mathrm{~m}$ by $1.0 \mathrm{~m}$ by $2.0 \mathrm{~m}$. Assuming that the container is completely full, that the temperature is $25.0{ }^{\circ} \mathrm{C}$ and that the atmospheric pressure is $1.0 \mathrm{~atm}$, calculate the percent (by volume) of air that would be displaced if all of the liquid nitrogen evaporated. (Liquid nitrogen has a density of $0.807 \mathrm{~g} / \mathrm{mL}$.)

Ronald Prasad

Numerade Educator

Problem 19

Which of the following gas samples, all at the same temperature, will have the greatest pressure? Explain.

David Collins

Numerade Educator

Problem 20

The following picture represents a sample of gas at a pressure of $1 \mathrm{~atm}$, a volume of $1 \mathrm{~L}$, and a temperature of $25^{\circ} \mathrm{C}$. Draw a similar picture showing what would happen if the volume were reduced to $0.5 \mathrm{~L}$ and the temperature increased to $250{ }^{\circ} \mathrm{C}$. What would happen to the pressure?

Dalton Hilovsky

Dalton Hilovsky

Numerade Educator

Problem 21

Aerosol cans carry clear warnings against incineration because of the high pressures that can develop upon heating. Suppose that a can contains a residual amount of gas at a pressure of $755 \mathrm{mmHg}$ and a temperature of $25^{\circ} \mathrm{C}$. What would be the pressure if the can were heated to $1155^{\circ} \mathrm{C}$ ?

Sisi Gao

Numerade Educator

Problem 22

A sample of nitrogen gas in a $1.75-\mathrm{L}$ container exerts a pressure of
1. 35 atm at $25^{\circ} \mathrm{C}$. What is the pressure if the volume of the container is maintained constant and the temperature is raised to $355^{\circ} \mathrm{C} ?$

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 23

Use the molar volume of a gas at STP to determine the volume (in
L) occupied by $10.0 \mathrm{~g}$ of neon at STP.

Kevin Chimex

Numerade Educator

Problem 24

Use the molar volume of a gas at STP to calculate the density (in
$\mathrm{g} / \mathrm{L}$ ) of carbon dioxide gas at STP.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 25

What is the density (in g/L) of hydrogen gas at $20.0^{\circ} \mathrm{C}$ and a pressure of 1655 psi?

Ly Tran

Numerade Educator

Problem 26

A sample of $\mathrm{N}_{2} \mathrm{O}$ gas has a density of $2.85 \mathrm{~g} / \mathrm{L}$ at $298 \mathrm{~K}$. What must be the pressure of the gas (in mmHg)?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 27

An experiment shows that a $248-\mathrm{mL}$ gas sample has a mass of $0.433 \mathrm{~g}$ at a pressure of $745 \mathrm{mmHg}$ and a temperature of $28^{\circ} \mathrm{C}$. What is the molar mass of the gas?

Shazia Naz

Numerade Educator

Problem 28

An experiment shows that a $113-\mathrm{mL}$ gas sample has a mass of $0.171 \mathrm{~g}$ at a pressure of $721 \mathrm{mmHg}$ and a temperature of $32{ }^{\circ} \mathrm{C}$. What is the molar mass of the gas?

Madeline Currie

Madeline Currie

Numerade Educator

Problem 29

A sample of gas has a mass of $38.8 \mathrm{mg}$. Its volume is $224 \mathrm{~mL}$ at a temperature of $55^{\circ} \mathrm{C}$ and a pressure of 886 torr. Find the molar mass of the gas.

Sisi Gao

Numerade Educator

Problem 30

A sample of gas has a mass of $0.555 \mathrm{~g}$. Its volume is $117 \mathrm{~mL}$ at a temperature of $85^{\circ} \mathrm{C}$ and a pressure of $753 \mathrm{mmHg}$. Find the molar mass of the gas.

Dalton Hilovsky

Dalton Hilovsky

Numerade Educator

Problem 31

A gas mixture contains each of the following gases at the indicated partial pressures: $\mathrm{N}_{2}$, 325 torr; $\mathrm{O}_{2}, 124$ torr; and $\mathrm{He}_{3}, 209$ torr. What is the total pressure of the mixture? What mass of each gas is present in a $1.05-\mathrm{L}$ sample of this mixture at $25.0^{\circ} \mathrm{C} ?$

David Collins

Numerade Educator

Problem 32

A gas mixture with a total pressure of $755 \mathrm{mmHg}$ contains each of the following gases at the indicated partial pressures: $\mathrm{CO}_{2}, 255$ $\mathrm{mmHg}_{\text {i }}$ Ar, $124 \mathrm{mmHg}$; and $\mathrm{O}_{2}, 167 \mathrm{mmHg}$. The mixture also contains helium gas. What is the partial pressure of the helium gas? What mass of helium gas is present in a $10.0$ -L sample of this mixture at $273 \mathrm{~K} ?$

Nicole Mabante

Numerade Educator

Problem 33

A $1.20-\mathrm{g}$ sample of dry ice is added to a $755-\mathrm{mL}$ flask containing nitrogen gas at a temperature of $25.0^{\circ} \mathrm{C}$ and a pressure of 725 $\mathrm{mmHg}$. The dry ice is allowed to sublime (convert from solid to
gas) and the mixture is allowed to return to $25.0{ }^{\circ} \mathrm{C}$. What is the total pressure in the flask?

Shahina -

Numerade Educator

Problem 34

A $275-\mathrm{mL}$ flask contains pure helium at a pressure of 752 torr. $A$ second flask with a volume of $475 \mathrm{~mL}$ contains pure argon at 3 pressure of 722 torr. If the two flasks are connected through a stopcock and the stopcock is opened, what are the partial pressures of each gas and the total pressure?

ES

Eugene Schneider

University of Minnesota - Twin Cities

Problem 35

A gas mixture contains $1.25 \mathrm{~g} \mathrm{~N}_{2}$ and $0.85 \mathrm{~g} \mathrm{O}_{2}$ in a $1.55-\mathrm{L}$ container at $18^{\circ} \mathrm{C}$. Calculate the mole fraction and partial pressure of each component in the gas mixture.

Sisi Gao

Numerade Educator

Problem 36

What is the mole fraction of oxygen gas in air (see Table 5.2)? What volume of air contains $10.0 \mathrm{~g}$ of oxygen gas at $273 \mathrm{~K}$ and $1.00 \mathrm{~atm} ?$

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 37

The hydrogen gas formed in a chemical reaction is collected over water at $30.0^{\circ} \mathrm{C}$ at a total pressure of $732 \mathrm{mmHg}$. What is the partial pressure of the hydrogen gas collected in this way? If the total volume of gas collected is $722 \mathrm{~mL}$, what mass of hydrogen gas is collected?

Sisi Gao

Numerade Educator

Problem 38

The air in a bicycle tire is bubbled through water and collected at $25^{\circ} \mathrm{C}$. If the total volume of gas collected is $5.45 \mathrm{~L}$ at a temperature of $25^{\circ} \mathrm{C}$ and a pressure of 745 torr, how many moles of gas were in the bicycle tire?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 39

The zinc within a copper-plated penny will dissolve in hydrochloric acid if the copper coating is filed down in several spots (so that the hydrochloric acid can get to the zinc). The reaction between the acid and the zinc is as follows:
$2 \mathrm{H}^{+}(a q)+\mathrm{Zn}(s) \rightarrow \mathrm{H}_{2}(g)+\mathrm{Zn}^{2+}(a q) .$ When the zinc in a
certain penny dissolves, the total volume of gas collected over water at $25^{\circ} \mathrm{C}$ was $0.951 \mathrm{~L}$ at a total pressure of $748 \mathrm{mmHg}$. What mass of hydrogen gas was collected?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 40

A heliox deep-sea diving mixture contains $2.0 \mathrm{~g}$ of oxygen to every $98.0 \mathrm{~g}$ of helium. What is the partial pressure of oxygen when this mixture is delivered at a total pressure of $8.5$ atm?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 41

Consider the following chemical reaction:
$$
\mathrm{C}(s)+\mathrm{H}_{2} \mathrm{O}(g) \longrightarrow \mathrm{CO}(g)+\mathrm{H}_{2}(g)
$$
How many liters of hydrogen gas is formed from the complete reaction of $15.7 \mathrm{~g}$ C? Assume that the hydrogen gas is collected at a pressure of $1.0$ atm and a temperature of $355 \mathrm{~K}$.

Sisi Gao

Numerade Educator

Problem 42

Consider the following chemical reaction.
$$
2 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow 2 \mathrm{H}_{2}(g)+\mathrm{O}_{2}(g)
$$
What mass of $\mathrm{H}_{2} \mathrm{O}$ is required to form $1.4 \mathrm{~L}$ of $\mathrm{O}_{2}$ at a temperature of $315 \mathrm{~K}$ and a pressure of $0.957 \mathrm{~atm} ?$

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 43

$\mathrm{CH}_{3} \mathrm{OH}$ can be synthesized by the following reaction.
$$
\mathrm{CO}(g)+2 \mathrm{H}_{2}(g) \longrightarrow \mathrm{CH}_{3} \mathrm{OH}(g)
$$
What volume of $\mathrm{H}_{2}$ gas (in $\mathrm{L}$ ), measured at $748 \mathrm{mmHg}$ and $86^{\circ} \mathrm{C}$, is required to synthesize $25.8 \mathrm{~g} \mathrm{CH}_{3} \mathrm{OH} ?$ How many liters of $\mathrm{CO}$ gas, measured under the same conditions, is required?

Sisi Gao

Numerade Educator

Problem 44

Oxygen gas reacts with powdered aluminum according to the following reaction:
$$
4 \mathrm{Al}(s)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{Al}_{2} \mathrm{O}_{3}(s)
$$
What volume of $\mathrm{O}_{2}$ gas (in $\mathrm{L}$ ), measured at $782 \mathrm{mmHg}$ and $25^{\circ} \mathrm{C}$, is required to completely react with $53.2 \mathrm{~g}$ Al?

Shahina -

Numerade Educator

Problem 45

Automobile air bags inflate following a serious impact. The impact triggers the following chemical reaction.
$$
2 \mathrm{NaN}_{3}(s) \longrightarrow 2 \mathrm{Na}(s)+3 \mathrm{~N}_{2}(g)
$$
If an automobile air bag has a volume of $11.8 \mathrm{~L}$, what mass of $\mathrm{NaN}_{3}$ (in $\mathrm{g}$ ) is required to fully inflate the air bag upon impact? Assume STP conditions.

Nicole Mabante

Numerade Educator

Problem 46

Lithium reacts with nitrogen gas according to the following reaction:
$$
6 \mathrm{Li}(s)+\mathrm{N}_{2}(g) \longrightarrow 2 \mathrm{Li}_{3} \mathrm{~N}(s)
$$
What mass of lithium (in $\mathrm{g}$ ) is required to react completely with $58.5 \mathrm{~mL}$ of $\mathrm{N}_{2}$ gas at STP?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 47

Hydrogen gas (a potential future fuel) can be formed by the reaction of methane with water according to the following equation:
$$
\mathrm{CH}_{4}(g)+\mathrm{H}_{2} \mathrm{O}(g) \longrightarrow \mathrm{CO}(g)+3 \mathrm{H}_{2}(g)
$$
In a particular reaction, $25.5 \mathrm{~L}$ of methane gas (measured at a pressure of 732 torr and a temperature of $25^{\circ} \mathrm{C}$ ) is mixed with $22.8 \mathrm{~L}$ of water vapor (measured at a pressure of 702 torr and a temperature of $125{ }^{\circ} \mathrm{C}$ ). The reaction produces $26.2 \mathrm{~L}$ of hydrogen gas measured at STP. What is the percent yield of the reaction?

David Collins

Numerade Educator

Problem 48

Ozone is depleted in the stratosphere by chlorine from $\mathrm{CF}_{3} \mathrm{Cl}$ according to the following set of equations:
$$
\begin{aligned}
\mathrm{CF}_{3} \mathrm{Cl}+\mathrm{UV} \text { light } & \longrightarrow \mathrm{CF}_{3}+\mathrm{Cl} \\
\mathrm{Cl}+\mathrm{O}_{3} & \longrightarrow \mathrm{ClO}+\mathrm{O}_{2} \\
\mathrm{O}_{3}+\mathrm{UV} \text { light } & \longrightarrow \mathrm{O}_{2}+\mathrm{O} \\
\mathrm{ClO}+\mathrm{O} \longrightarrow \mathrm{Cl}+\mathrm{O}_{2}
\end{aligned}
$$
What total volume of ozone measured at a pressure of $25.0$ $\mathrm{mmHg}$ and a temperature of $225 \mathrm{~K}$ can be destroyed when all of the chlorine from $15.0 \mathrm{~g}$ of $\mathrm{CF}_{3} \mathrm{Cl}$ goes through ten cycles of the above reactions?

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 49

Consider a $1.0-\mathrm{L}$ sample of helium gas and a $1.0-\mathrm{L}$ sample of argon gas, both at room temperature and atmospheric pressure.
a. Do the atoms in the helium sample have the same average kinetic energy as the atoms in the argon sample?
b. Do the atoms in the helium sample have the same average velocity as the atoms in the argon sample?
c. Do the argon atoms, since they are more massive, exert a greater pressure on the walls of the container? Explain.
d. Which gas sample would have the fastest rate of effusion?

David Collins

Numerade Educator

Problem 50

A flask at room temperature contains exactly equal amounts (in moles) of nitrogen and xenon.
a. Which of the two gases exerts the greater partial pressure?
b. The molecules or atoms of which gas have the greater average velocity?
c. The molecules of which gas have the greater average kinetic energy?
d. If a small hole were opened in the flask, which gas would effuse more quickly?

ES

Eugene Schneider

University of Minnesota - Twin Cities

Problem 51

Calculate the root mean square velocity and kinetic energy of $\mathrm{F}_{2}$, $\mathrm{Cl}_{2}$, and $\mathrm{Br}_{2}$ at $298 \mathrm{~K}$. Rank the three halogens with respect to their rate of effusion.

Sisi Gao

Numerade Educator

Problem 52

Calculate the root mean square velocity and kinetic energy of CO, $\mathrm{CO}_{2}$, and $\mathrm{SO}_{3}$ at $298 \mathrm{~K}$. Which gas has the greatest velocity? The greatest kinetic energy? The greatest effusion rate?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 53

Uranium- 235 can be separated from U-238 by fluorinating the uranium to form $\mathrm{UF}_{6}$ (which is a gas) and then taking advantage of the different rates of effusion and diffusion for compounds containing the two isotopes. Calculate the ratio of effusion rates for ${ }^{238} \mathrm{UF}_{6}$ and ${ }^{235} \mathrm{UF}_{6}$. The atomic mass of U-235 is $235.054 \mathrm{amu}$ and that of $\mathrm{U}-238$ is $238.051$ amu.

Dominique Jan Tan

Dominique Jan Tan

Numerade Educator

Problem 54

Calculate the ratio of effusion rates for Ar and Kr.

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 55

A sample of neon effuses from a container in 76 seconds. The same amount of an unknown noble gas requires 155 seconds. Identify the gas.

Noah Barguez-Arias

Noah Barguez-Arias

Numerade Educator

Problem 56

A sample of $\mathrm{N}_{2} \mathrm{O}$ effuses from a container in 42 seconds. How long would it take the same amount of gaseous $\mathrm{I}_{2}$ to effuse from the same container under identical conditions?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 57

The following graph shows the distribution of molecular velocities for two different molecules ( $\mathrm{A}$ and $\mathrm{B}$ ) at the same temperature. Which molecule has the higher molar mass? Which molecule would have the higher rate of effusion?

Sisi Gao

Numerade Educator

Problem 58

The following graph shows the distribution of molecular velocities for the same molecule at two different temperatures ( $T_{1}$ and $T_{2}$ ). Which temperature is greater? Explain.

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 59

Which postulate of the kinetic molecular theory breaks down under conditions of high pressure? Explain.

Kevin Chimex

Numerade Educator

Problem 60

Which postulate of the kinetic molecular theory breaks down under conditions of low temperature? Explain.

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 61

Use the van der Waals equation and the ideal gas equation to calculate the volume of $1.000 \mathrm{~mol}$ of neon at a pressure of $500.0 \mathrm{~atm}$ and a temperature of $355.0 \mathrm{~K}$. Explain why the two values are different.

Christopher Dzorkpata

Christopher Dzorkpata

Numerade Educator

Problem 62

Use the van der Waals equation and the ideal gas equation to calculate the pressure exerted by $1.000 \mathrm{~mol}$ of $\mathrm{Cl}_{2}$ in a volume of $5.000 \mathrm{~L}$ at a temperature of $273.0 \mathrm{~K}$. Explain why the two values are different.

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 63

Modern pennies are composed of zinc coated with copper. A student determines the mass of a penny to be $2.482 \mathrm{~g}$ and then makes several scratches in the copper coating (to expose the underlying zinc). The student puts the scratched penny in hydrochloric acid, where the following reaction occurs between the zinc and the $\mathrm{HCl}$ (the copper remains undissolved):
$$
\mathrm{Zn}(s)+2 \mathrm{HCl}(a q) \longrightarrow \mathrm{H}_{2}(g)+\mathrm{ZnCl}_{2}(a q)
$$
The student collects the hydrogen produced over water at $25^{\circ} \mathrm{C}$. The collected gas occupies a volume of $0.899 \mathrm{~L}$ at a total pressure of $791 \mathrm{mmHg}$. Calculate the percent zinc in the penny. (Assume that all the $\mathrm{Zn}$ in the penny dissolves.)

Sisi Gao

Numerade Educator

Problem 64

A $2.85-\mathrm{g}$ sample of an unknown chlorofluorocarbon is decomposed and produces $564 \mathrm{~mL}$ of chlorine gas at a pressure of 752 $\mathrm{mmHg}$ and a temperature of $298 \mathrm{~K}$. What is the percent chlorine (by mass) in the unknown chlorofluorocarbon?

ES

Eugene Schneider

University of Minnesota - Twin Cities

Problem 65

The mass of an evacuated $255-\mathrm{mL}$ flask is $143.187 \mathrm{~g}$. The mass of the flask filled with 267 torr of an unknown gas at $25^{\circ} \mathrm{C}$ is $143.289 \mathrm{~g}$. Calculate the molar mass of the unknown gas.

Sisi Gao

Numerade Educator

Problem 66

A $118-\mathrm{mL}$ flask is evacuated and found to have a mass of $97.129 \mathrm{~g}$. When the flask is filled with 768 torr of helium gas at $35^{\circ} \mathrm{C}$, it is found to have a mass of $97.171 \mathrm{~g}$. Was the helium gas pure?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 67

A gaseous hydrogen and carbon containing compound is decomposed and found to contain $82.6696$ carbon and $17.34 \%$ hydrogen by mass. The mass of $158 \mathrm{~mL}$ of the gas, measured at $556 \mathrm{mmHg}$ and $25^{\circ} \mathrm{C}$, was found to be $0.275 \mathrm{~g}$. What is the molecular formula of the compound?

Shahina -

Numerade Educator

Problem 68

A gaseous hydrogen and carbon containing compound is decomposed and found to contain $85.63 \% \mathrm{C}$ and $14.37 \% \mathrm{H}$ by mass. The mass of $258 \mathrm{~mL}$ of the gas, measured at STP, was found to be
$0.646 \mathrm{~g}$. What is the molecular formula of the compound?

George Bennett

Numerade Educator

Problem 69

Consider the following reaction:
$$
2 \mathrm{NiO}(s) \longrightarrow 2 \mathrm{Ni}(s)+\mathrm{O}_{2}(g)
$$
If $\mathrm{O}_{2}$ is collected over water at $40.0^{\circ} \mathrm{C}$ and a total pressure of 745 $\mathrm{mmH} \mathrm{g}$, what volume of gas will be collected for the complete reaction of $24.78 \mathrm{~g}$ of $\mathrm{NiO} ?$

Sisi Gao

Numerade Educator

Problem 70

The following reaction forms $15.8 \mathrm{~g}$ of $\mathrm{Ag}(s)$ :
$$
2 \mathrm{Ag}_{2} \mathrm{O}(s) \longrightarrow 4 \mathrm{Ag}(s)+\mathrm{O}_{2}(g)
$$
What total volume of gas forms if it is collected over water at a temperature of $25^{\circ} \mathrm{C}$ and a total pressure of $752 \mathrm{mmHg}$ ?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 71

When hydrochloric acid is poured over potassium sulfide, $42.9$ $\mathrm{mL}$ of hydrogen sulfide gas is produced at a pressure of 752 torr and $25.8^{\circ} \mathrm{C}$. Write an equation for the gas-evolution reaction and determine how much potassium sulfide (in grams) reacted.

Sisi Gao

Numerade Educator

Problem 72

Consider the following reaction:
$$
2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{SO}_{3}(g)
$$
a. If $285.5 \mathrm{~mL}$ of $\mathrm{SO}_{2}$ is allowed to react with $158.9 \mathrm{~mL}$ of $\mathrm{O}_{2}$ (both measured at $315 \mathrm{~K}$ and $50.0 \mathrm{mmHg}$ ), what is the limiting reactant and the theoretical yield of $\mathrm{SO}_{3} ?$
b. If $187.2 \mathrm{~mL}$ of $\mathrm{SO}_{3}$ is collected (measured at $315 \mathrm{~K}$ and $50.0$ $\mathrm{mmHg}$ ), what is the percent yield for the reaction?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 73

Ammonium carbonate decomposes upon heating according to the following balanced equation:
$$
\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}(s) \longrightarrow 2 \mathrm{NH}_{3}(g)+\mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(g)
$$
Calculate the total volume of gas produced at $22{ }^{\circ} \mathrm{C}$ and $1.02 \mathrm{~atm}$ by the complete decomposition of $11.83 \mathrm{~g}$ of ammonium carbonate.

Dalton Hilovsky

Dalton Hilovsky

Numerade Educator

Problem 74

Ammonium nitrate decomposes explosively upon heating according to the following balanced equation:
$$
2 \mathrm{NH}_{4} \mathrm{NO}_{3}(s) \longrightarrow 2 \mathrm{~N}_{2}(g)+\mathrm{O}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g)
$$
Calculate the total volume of gas (at $125^{\circ} \mathrm{C}$ and $748 \mathrm{mmHg}$ ) produced by the complete decomposition of $1.55 \mathrm{~kg}$ of ammonium nitrate.

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 75

Olympic cyclists fill their tires with helium to make them lighter. Calculate the mass of air in an air-filled tire and the mass of helium in a helium-filled tire. What is the mass difference between the two? Assume that the volume of the tire is 855 $\mathrm{mL}$, that it is filled to a total pressure of $125 \mathrm{psi}$, and that the temperature is $25^{\circ} \mathrm{C}$. Also, assume an average molar mass for air of $28.8 \mathrm{~g} / \mathrm{mol}$.

Sisi Gao

Numerade Educator

Problem 76

In a common classroom demonstration, a balloon is filled with air and submerged in liquid nitrogen. The balloon contracts as the gases within the balloon cool. Suppose the balloon initially contains $2.95 \mathrm{~L}$ of air at a temperature of $25.0^{\circ} \mathrm{C}$ and a pressure of $0.998$ atm. Calculate the expected volume of the balloon upon cooling to $-196^{\circ} \mathrm{C}$ (the boiling point of liquid nitrogen). When the demonstration is carried out, the actual volume of the balloon decreases to $0.61 \mathrm{~L}$. How well does the observed volume of the balloon compare to your calculated value? Can you explain the difference?

Ronald Prasad

Numerade Educator

Problem 77

Gaseous ammonia can be injected into the exhaust stream of a coal-burning power plant to reduce the pollutant $\mathrm{NO}$ to $\mathrm{N}_{2}$ according to the following reaction:
$$
4 \mathrm{NH}_{3}(g)+4 \mathrm{NO}(g)+\mathrm{O}_{2}(g) \longrightarrow 4 \mathrm{~N}_{2}(g)+6 \mathrm{H}_{2} \mathrm{O}(g)
$$
Suppose that the exhaust stream of a power plant has a flow rate of $335 \mathrm{~L} / \mathrm{s}$ at a temperature of $955 \mathrm{~K}$, and that the exhaust contains a partial pressure of $\mathrm{NO}$ of $22.4$ torr. What should be the flow rate of ammonia delivered at 755 torr and $298 \mathrm{~K}$ into the stream to react completely with the $\mathrm{NO}$ if the ammonia is $65.29 \mathrm{f}$ pure (by volume)?

David Collins

Numerade Educator

Problem 78

The emission of $\mathrm{NO}_{2}$ by fossil fuel combustion can be prevented by injecting gaseous urea into the combustion mixture. The urea reduces $\mathrm{NO}$ (which oxidizes in air to form $\mathrm{NO}_{2}$ ) according to the following reaction:
$\begin{aligned} 2 \mathrm{CO}\left(\mathrm{NH}_{2}\right)_{2}(g)+4 \mathrm{NO}(g)+\mathrm{O}_{2}(g) & \longrightarrow \\ & 4 \mathrm{~N}_{2}(g)+2 \mathrm{CO}_{2}(g)+4 \mathrm{H}_{2} \mathrm{O}(g) \end{aligned}$
Suppose that the exhaust stream of an automobile has a flow rate of $2.55 \mathrm{~L} / \mathrm{s}$ at $655 \mathrm{~K}$ and contains a partial pressure of $\mathrm{NO}$ of $12.4$ torr. What total mass of urea is necessary to react completely with the NO formed during $8.0$ hours of driving?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 79

An ordinary gasoline can measuring $30.0 \mathrm{~cm}$ by $20.0 \mathrm{~cm}$ by $15.0$ $\mathrm{cm}$ is evacuated with a vacuum pump. Assuming that virtually all of the air can be removed from inside the can, and that atmospheric pressure is $14.7$ psi, what is the total force (in pounds) on the surface of the can? Do you think that the can could withstand the force?

Sisi Gao

Numerade Educator

Problem 80

Twenty-five milliliters of liquid nitrogen (density $=0.807 \mathrm{~g} / \mathrm{mL}$ ) is poured into a cylindrical container with a radius of $10.0 \mathrm{~cm}$ and a length of $20.0 \mathrm{~cm}$. The container initially contains only air at a pressure of $760.0 \mathrm{mmHg}$ (atmospheric pressure) and a temperature of $298 \mathrm{~K}$. If the liquid nitrogen completely vaporizes, what is the total force (in $\mathbb{l b}$ ) on the interior of the container at $298 \mathrm{~K}$ ?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 81

A $160.0$ - L helium tank contains pure helium at a pressure of 1855 psi and a temperature of $298 \mathrm{~K}$. How many $3.5$ - $\mathrm{L}$ helium balloons can be filled from the helium in the tank? (Assume an atmospheric pressure of $1.0 \mathrm{~atm}$ and a temperature of $298 \mathrm{~K} .$ )

Sisi Gao

Numerade Educator

Problem 82

A $11.5-\mathrm{mL}$ sample of liquid butane (density $=0.573 \mathrm{~g} / \mathrm{mL}$ ) is evaporated in an otherwise empty container at a temperature of $28.5^{\circ} \mathrm{C}$. The pressure in the container following evaporation is 892 torr. What is the volume of the container?

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 83

A scuba diver creates a spherical bubble with a radius of $2.5 \mathrm{~cm}$ at a depth of $30.0 \mathrm{~m}$ where the total pressure (including atmospheric pressure) is $4.00 \mathrm{~atm} .$ What is the radius of the bubble when it reaches the surface of the water? (Assume atmospheric pressure to be $1.00$ atm and the temperature to be $298 \mathrm{~K}$.)

Sisi Gao

Numerade Educator

Problem 84

A particular balloon can be stretched to a maximum surface area of $1257 \mathrm{~cm}^{2}$. The balloon is filled with $3.0 \mathrm{~L}$ of helium gas at a pressure of 755 torr and a temperature of $298 \mathrm{~K}$. The balloon is then allowed to rise in the atmosphere. Assume an atmospheric temperature of $273 \mathrm{~K}$ and determine at what pressure the balloon will burst. (Assume the balloon to be in the shape of a sphere.)

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 85

A catalytic converter in an automobile uses a palladium or platinum catalyst (a substance that increases the rate of a reaction without being consumed by the reaction) to convert carbon monoxide gas to carbon dioxide according to the following reaction:
$$
2 \mathrm{CO}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{CO}_{2}(g)
$$
A chemist researching the effectiveness of a new catalyst combines a $2.0: 1.0$ mole ratio mixture of carbon monoxide and oxygen gas (respectively) over the catalyst in a $2.45-\mathrm{L}$ flask at a total pressure of 745 torr and a temperature of $552{ }^{\circ} \mathrm{C}$. When the reaction is complete, the pressure in the flask has dropped to 552 torr. What percentage of the carbon monoxide was converted to carbon dioxide?

Sisi Gao

Numerade Educator

Problem 86

A quantity of $\mathrm{N}_{2}$ occupies a volume of $1.0 \mathrm{~L}$ at $300 \mathrm{~K}$ and $1.0 \mathrm{~atm}$. The gas expands to a volume of $3.0 \mathrm{~L}$ as the result of a change in both temperature and pressure. Find the density of the gas at these new conditions.

Shahina -

Numerade Educator

Problem 87

A mixture of $\mathrm{CO}(g)$ and $\mathrm{O}_{2}(g)$ in a $1.0-\mathrm{L}$ container at $1.0 \times 10^{3} \mathrm{~K}$ has a total pressure of $2.2$ atm. After some time the total pressure falls to $1.9 \mathrm{~atm}$ as the result of the formation of $\mathrm{CO}_{2}$. Find the amount of $\mathrm{CO}_{2}$ that forms.

Narayan Hari

Numerade Educator

Problem 88

The radius of a xenon atom is $1.3 \times 10^{-8} \mathrm{~cm} .$ A $100-\mathrm{mL}$ flask is filled with Xe at a pressure of $1.0$ atm and a temperature of $273 \mathrm{~K}$. Calculate the fraction of the volume that is occupied by Xe atoms. (Hint: The atoms are spheres.)

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 89

A natural gas storage tank is a cylinder with a moveable top whose volume can change only as its height changes. Its radius remains fixed. The height of the cylinder is $22.6 \mathrm{~m}$ on a day when the temperature is $22{ }^{\circ} \mathrm{C}$. The next day the height of the cylinder increases to $23.8 \mathrm{~m}$ as the gas expands because of a heat wave. Find the temperature, assuming that the pressure and amount of gas in the storage tank have not changed.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 90

A mixture of $8.0 \mathrm{~g} \mathrm{CH}_{4}$ and $8.0 \mathrm{~g} \mathrm{Xe}$ is placed in a container and the total pressure is found to be $0.44$ atm. Find the partial pressure of $\mathrm{CH}_{4}$.

Dalton Hilovsky

Dalton Hilovsky

Numerade Educator

Problem 91

A steel container of volume $0.35 \mathrm{~L}$ can withstand pressures up to 88 atm before exploding. Find the mass of helium that can be stored in this container at $299 \mathrm{~K}$.

Aparna Shakti

Numerade Educator

Problem 92

Binary compounds of alkali metals and hydrogen react with water to liberate $\mathrm{H}_{2}(\mathrm{~g}) .$ The $\mathrm{H}_{2}$ from the reaction of a sample of $\mathrm{NaH}$ with an excess of water fills a volume of $0.490 \mathrm{~L}$ above the water. The temperature of the gas is $35^{\circ} \mathrm{C}$ and the total pressure is 758 $\mathrm{mmHg}$. Find the mass of $\mathrm{H}_{2}$ liberated and the mass of NaH that reacted.

Matthew Bamidele

Matthew Bamidele

Numerade Educator

Problem 93

In a given diffusion apparatus, $15.0 \mathrm{~mL}$ of $\mathrm{HBr}$ gas diffused in $1.0$ min. In the same apparatus and under the same conditions, $20.3$ $\mathrm{mL}$ of an unknown gas diffused in $1.0 \mathrm{~min}$. The unknown gas is a hydrocarbon. Find its molecular formula.

Aadit Sharma

Numerade Educator

Problem 94

The world burns approximately $9.0 \times 10^{12} \mathrm{~kg}$ of fossil fuel per year. Use the combustion of octane as the representative reaction and determine the mass of carbon dioxide (the most significant greenhouse gas) formed per year by this combustion. The current concentration of carbon dioxide in the atmosphere is approximately 387 ppm (by volume). By what percentage does the concentration increase in one year due to fossil fuel combustion? Approximate the average properties of the entire atmosphere by assuming that the atmosphere extends from sea level to $15 \mathrm{~km}$ and that it has an average pressure of 381 torr and average temperature of $275 \mathrm{~K}$. Assume Earth is a perfect sphere with a radius of $6371 \mathrm{~km}$.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 95

The atmosphere slowly oxidizes hydrocarbons in a number of steps that eventually convert the hydrocarbon into carbon dioxide and water. The overall reactions of a number of such steps for methane gas is as follows:
$$
\begin{aligned}
\mathrm{CH}_{4}(g)+5 \mathrm{O}_{2}(g)+5 \mathrm{NO}(g) & \longrightarrow \\
\mathrm{CO}_{2}(g) &+\mathrm{H}_{2} \mathrm{O}(g)+5 \mathrm{NO}_{2}(g)+2 \mathrm{OH}(g)
\end{aligned}
$$
Suppose that an atmospheric chemist combines $155 \mathrm{~mL}$ of methane at STP, $885 \mathrm{~mL}$ of oxygen at STP, and $55.5 \mathrm{~mL}$ of $\mathrm{NO}$ at STP in a 2.0-L flask. The reaction is allowed to stand for several weeks at $275 \mathrm{~K}$. If the reaction reaches $90.0 \%$ of completion (90.096 of the limiting reactant is consumed), what are the partial pressures of each of the reactants and products in the flask at $275 \mathrm{~K} ?$ What is the total pressure in the flask?

David Collins

Numerade Educator

Problem 96

Two identical balloons are filled to the same volume, one with air and one with helium. The next day, the volume of the air-filled balloon has decreased by $5.0 \%$. By what percent has the volume of the helium-filled balloon decreased? (Assume that the air is fourfifths nitrogen and one-fifth oxygen, and that the temperature did not change.)

ES

Eugene Schneider

University of Minnesota - Twin Cities

Problem 97

A mixture of $\mathrm{CH}_{4}(\mathrm{~g})$ and $\mathrm{C}_{2} \mathrm{H}_{6}(g)$ has a total pressure of $0.53$ atm. Just enough $\mathrm{O}_{2}(g)$ is added to the mixture to bring about its complete combustion to $\mathrm{CO}_{2}(g)$ and $\mathrm{H}_{2} \mathrm{O}(g) .$ The total pressure of the two product gases is found to be $2.2 \mathrm{~atm}$. Assuming constant volume and temperature, find the mole fraction of $\mathrm{CH}_{4}$ in the mixture.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 98

A sample of $\mathrm{C}_{2} \mathrm{H}_{2}(g)$ has a pressure of $7.8 \mathrm{kPa}$. After some time a portion of it reacts to form $\mathrm{C}_{6} \mathrm{H}_{6}(g) .$ The total pressure of the mixture of gases is then $3.9 \mathrm{kPa}$. Assume the volume and the temperature do not change. Find the fraction of $\mathrm{C}_{2} \mathrm{H}_{2}(g)$ that has undergone reaction.

ES

Eugene Schneider

University of Minnesota - Twin Cities

Problem 99

When the driver of an automobile applies the brakes, the passengers are pushed toward the front of the car, but a helium balloon is pushed toward the back of the car. Upon forward acceleration, the passengers are pushed toward the back of the car, but the helium balloon is pushed toward the front of the car. Why?

Sisi Gao

Numerade Educator

Problem 100

The following reaction occurs in a closed container:
$$
\mathrm{A}(\mathrm{g})+2 \mathrm{~B}(g) \longrightarrow 2 \mathrm{C}(g)
$$
A reaction mixture initially contains $1.5 \mathrm{~L}$ of $\mathrm{A}$ and $2.0 \mathrm{~L}$ of $\mathrm{B}$. Assuming that the volume and temperature of the reaction mixture remain constant, what is the percent change in pressure if the reaction goes to completion?

Sisi Gao

Numerade Educator

Problem 101

One mole of nitrogen and one mole of neon are combined in a closed container at STP. How big is the container?

ES

Eugene Schneider

University of Minnesota - Twin Cities

Problem 102

Exactly equal amounts (in moles) of gas $\mathrm{A}$ and $\mathrm{gas} \mathrm{B}$ are combined in a 1 - $L$ container at room temperature. Gas $B$ has a molar mass that is twice that of gas $A .$ Which of the following is true for the mixture of gases and why?
a. The molecules of gas $B$ have greater kinetic energy than those of $\operatorname{gas} A$.
b. Gas $B$ has a greater partial pressure than gas $\mathrm{A}$.
c. The molecules of gas $\mathrm{B}$ have a greater average velocity than those of gas $\mathrm{A}$.
d. Gas B makes a greater contribution to the average density of the mixture than gas $A$.

Dominique Jan Tan

Dominique Jan Tan

Numerade Educator

Problem 103

Which of the following gases would you expect to deviate most from ideal behavior under conditions of low temperature:
$\mathrm{F}_{2}, \mathrm{Cl}_{2}$, or $\mathrm{Br}_{2} ?$ Explain.

Matthew Bamidele

Matthew Bamidele

Numerade Educator