Chemistry

Raymond Chang, Kenneth A. Goldsby

Chapter 20 Chemistry in the Atmosphere - all with Video Answers

Educators

Chapter Questions

02:06

Problem 1

Describe the regions of Earth's atmosphere.

Wan Deng

Numerade Educator

05:44

Problem 2

Briefly outline the main processes of the nitrogen and oxygen cycles.

Wan Deng

Numerade Educator

01:08

Problem 3

Explain why, for maximum performance, supersonic airplanes need to fly at a high altitude (in the stratosphere).

Wan Deng

Numerade Educator

02:37

Jupiter's atmosphere consists mainly of hydrogen (90 percent) and helium (9 percent). How does this mixture of gases contrast with the composition of Earth's atmosphere? Why does the composition differ?

Wan Deng

Numerade Educator

01:34

Problem 5

Referring to Table $20.1,$ calculate the mole fraction of $\mathrm{CO}_{2}$ and its concentration in parts per million by volume.

Wan Deng

Numerade Educator

02:11

Problem 6

Calculate the partial pressure of $\mathrm{CO}_{2}$ (in atm) in dry air when the atmospheric pressure is $754 \mathrm{mmHg}$.

Wan Deng

Numerade Educator

02:25

Problem 7

Describe the processes that result in the warming of the stratosphere.

Wan Deng

Numerade Educator

05:00

Problem 8

Calculate the total mass (in kilograms) of nitrogen, oxygen, and carbon dioxide gases in the atmosphere. (Hint: See Problem 5.106 and Table 20.1. Use 29.0 g/mol for the molar mass of air.)

Wan Deng

Numerade Educator

01:11

Problem 9

What process gives rise to aurora borealis and aurora australis?

Wan Deng

Numerade Educator

03:46

Problem 10

Why can astronauts not release oxygen atoms to test the mechanism of shuttle glow?

Wan Deng

Numerade Educator

02:50

Problem 11

The highly reactive OH radical (a species with an unpaired electron) is believed to be involved in some atmospheric processes. Table 9.4 lists the bond enthalpy for the oxygen-to-hydrogen bond in $\widehat{\mathrm{OH}}$ as $460 \mathrm{kJ} / \mathrm{mol} .$ What is the longest wavelength (in $\mathrm{nm}$ ) of radiation that can bring about the reaction $$\mathrm{OH}(g) \longrightarrow \mathrm{O}(g)+\mathrm{H}(g)$$.

Wan Deng

Numerade Educator

01:31

Problem 12

The green color observed in aurora borealis is produced by the emission of a photon by an electronically excited oxygen atom at $558 \mathrm{nm} .$ Calculate the energy difference between the two levels involved in the emission process.

Wan Deng

Numerade Educator

01:55

Problem 13

Briefly describe the absorption of solar radiation in the stratosphere by $\mathrm{O}_{2}$ and $\mathrm{O}_{3}$ molecules.

Wan Deng

Numerade Educator

01:38

Problem 14

Explain the processes that have a warming effect on the stratosphere.

Wan Deng

Numerade Educator

01:39

Problem 15

List the properties of CFCs, and name four major uses of these compounds.

Wan Deng

Numerade Educator

03:14

Problem 16

How do CFCs and nitrogen oxides destroy ozone in the stratosphere?

Wan Deng

Numerade Educator

02:02

Problem 17

What causes the polar ozone holes?

Wan Deng

Numerade Educator

00:49

Problem 18

How do volcanic eruptions contribute to ozone destruction?

Wan Deng

Numerade Educator

01:55

Problem 19

Describe ways to curb the destruction of ozone in the stratosphere.

Wan Deng

Numerade Educator

02:11

Problem 20

Discuss the effectiveness of some of the CFC substitutes.

Wan Deng

Numerade Educator

06:39

Problem 21

Given that the quantity of ozone in the stratosphere is equivalent to a 3.0 -mm-thick layer of ozone on Earth at STP, calculate the number of ozone molecules in the stratosphere and their mass in kilograms. (Hint: The radius of Earth is $6371 \mathrm{km}$ and the surface area of a sphere is $4 \pi r^{2}$ where $r$ is the radius.)

Wan Deng

Numerade Educator

05:09

Problem 22

Referring to the answer in Problem $20.21,$ and assuming that the level of ozone in the stratosphere has already fallen 6.0 percent, calculate the number of kilograms of ozone that would have to be manufactured on a daily basis so that we could restore the ozone to the original level in 100 yr. If ozone is made according to the process $3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{O}_{3}(g),$
how many kilojoules of energy would be required?

Wan Deng

Numerade Educator

01:01

Problem 23

Both Freon-11 and Freon-12 are made by the reaction of carbon tetrachloride (CCl_) with hydrogen fluoride. Write equations for these reactions.

Wan Deng

Numerade Educator

01:31

Problem 24

Why are CFCs not decomposed by UV radiation in the troposphere?

Wan Deng

Numerade Educator

03:39

Problem 25

The average bond enthalpies of the $\mathrm{C}-\mathrm{Cl}$ and $\mathrm{C}-\mathrm{F}$ bonds are $340 \mathrm{kJ} / \mathrm{mol}$ and $485 \mathrm{kJ} / \mathrm{mol},$ respectively. Based on this information, explain why the $\mathrm{C}-\mathrm{Cl}$ bond in a CFC molecule is preferentially broken by solar radiation at $250 \mathrm{nm}$.

Wan Deng

Numerade Educator

04:18

Problem 26

Like CFCs, certain bromine-containing compounds such as $\mathrm{CF}_{3} \mathrm{Br}$ can also participate in the destruction of ozone by a similar mechanism starting with the Br atom: $$\mathrm{CF}_{3} \mathrm{Br} \longrightarrow \mathrm{CF}_{3}+\mathrm{Br}.$$ Given that the average $\mathrm{C}-\mathrm{Br}$ bond enthalpy is $276 \mathrm{kJ} / \mathrm{mol},$ estimate the longest wavelength required to break this bond. Will this compound be decomposed in the troposphere only or in both the troposphere and stratosphere?

Wan Deng

Numerade Educator

04:17

Problem 27

Draw Lewis structures for chlorine nitrate (ClONO $_{2}$ ) and chlorine monoxide (ClO).

Wan Deng

Numerade Educator

02:50

Problem 28

Draw Lewis structures for HCFC-123 (CF $_{3} \mathrm{CHCl}_{2}$ ) and $\mathrm{CF}_{3} \mathrm{CFH}_{2}$.

Wan Deng

Numerade Educator

01:56

Problem 29

What are the effects of volcanic eruptions on climate?

Wan Deng

Numerade Educator

01:30

Problem 30

Classify the reaction between $\mathrm{H}_{2} \mathrm{S}$ and $\mathrm{SO}_{2}$ that leads to the formation of sulfur at the site of a volcanic eruption.

Wan Deng

Numerade Educator

09:17

Problem 31

What is the greenhouse effect? What is the criterion for classifying a gas as a greenhouse gas?

Wan Deng

Numerade Educator

01:11

Problem 32

Why is more emphasis placed on the role of carbon dioxide in the greenhouse effect than on that of water?

Wan Deng

Numerade Educator

02:35

Problem 33

Describe three human activities that generate carbon dioxide. List two major mechanisms for the uptake of carbon dioxide.

Wan Deng

Numerade Educator

01:21

Problem 34

Deforestation contributes to the greenhouse effect in two ways. What are they?

Wan Deng

Numerade Educator

01:14

Problem 35

How does an increase in world population enhance the greenhouse effect?

Wan Deng

Numerade Educator

02:52

Problem 36

Is ozone a greenhouse gas? If so, sketch three ways an ozone molecule can vibrate.

Wan Deng

Numerade Educator

01:37

Problem 37

What effects do CFCs and their substitutes have on Earth's temperature?

Wan Deng

Numerade Educator

01:49

Problem 38

Why are CFCs more effective greenhouse gases than methane and carbon dioxide?

Wan Deng

Numerade Educator

04:29

Problem 39

The annual production of zinc sulfide (ZnS) is $4.0 \times 10^{4}$ tons. Estimate the number of tons of $\mathrm{SO}_{2}$ produced by roasting it to extract zinc metal.

Iryna Ivaniuk

Numerade Educator

02:56

Problem 40

Calcium oxide or quicklime (CaO) is used in steel making, cement manufacture, and pollution control It is prepared by the thermal decomposition of calcium carbonate: $$\mathrm{CaCO}_{3}(s) \longrightarrow \mathrm{CaO}(s)+\mathrm{CO}_{2}(g).$$ Calculate the yearly release of $\mathrm{CO}_{2}$ (in kilograms) to the atmosphere if the annual production of $\mathrm{CaO}$ in the United States is $1.7 \times 10^{10} \mathrm{kg}$.

Iryna Ivaniuk

Numerade Educator

04:38

Problem 41

The molar heat capacity of a diatomic molecule is 29.1 J/K \cdot mol. Assuming the atmosphere contains only nitrogen gas and there is no heat loss, calculate the total heat intake (in kilojoules) if the atmosphere warms up by $3^{\circ} \mathrm{C}$ during the next 50 yr. Given that there are $1.8 \times 10^{20}$ moles of diatomic molecules present, how many kilograms of ice (at the North and South Poles) will this quantity of heat melt at $0^{\circ} \mathrm{C} ?$ (The molar heat of fusion of ice is $6.01 \mathrm{kJ} / \mathrm{mol}$.)

Iryna Ivaniuk

Numerade Educator

02:09

Problem 42

As mentioned in the chapter, spraying the stratosphere with hydrocarbons such as ethane and propane should eliminate Cl atoms. What is the drawback of this procedure if used on a large scale for an extended period of time?

Kenneth Jordan

Numerade Educator

02:22

Problem 43

Name the gas that is largely responsible for the acid rain phenomenon.

Iryna Ivaniuk

Numerade Educator

02:13

Problem 44

List three detrimental effects of acid rain.

Iryna Ivaniuk

Numerade Educator

02:13

Problem 45

Briefly discuss two industrial processes that lead to acid rain.

Iryna Ivaniuk

Numerade Educator

04:02

Problem 46

Discuss ways to curb acid rain.

Iryna Ivaniuk

Numerade Educator

01:21

Problem 47

Water and sulfur dioxide are both polar molecules and their geometry is similar. Why is $\mathrm{SO}_{2}$ not considered a major greenhouse gas?

Prashant Bana

Numerade Educator

02:13

Problem 48

Describe the removal of $\mathrm{SO}_{2}$ by $\mathrm{CaO}$ (to form $\mathrm{CaSO}_{3}$ ) in terms of a Lewis acid-base reaction.

Iryna Ivaniuk

Numerade Educator

03:18

Problem 49

An electric power station annually burns $3.1 \times 10^{7} \mathrm{kg}$ of coal containing 2.4 percent sulfur by mass. Calculate the volume of $\mathrm{SO}_{2}$ emitted at STP.

Iryna Ivaniuk

Numerade Educator

05:59

Problem 50

The concentration of $\mathrm{SO}_{2}$ in the troposphere over a certain region is 0.16 ppm by volume. The gas dissolves in rainwater as follows: $$\mathrm{SO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{HSO}_{3}^{-}(a q)$$.Given that the equilibrium constant for the preceding reaction is $1.3 \times 10^{-2},$ calculate the $\mathrm{pH}$ of the rainwater. Assume that the reaction does not affect the partial pressure of $\mathrm{SO}_{2}$.

Kenneth Jordan

Numerade Educator

04:31

Problem 51

What is photochemical smog? List the factors that favor the formation of photochemical smog.

Iryna Ivaniuk

Numerade Educator

03:17

Problem 52

What are primary and secondary pollutants?

Iryna Ivaniuk

Numerade Educator

01:10

Problem 53

Identify the gas that is responsible for the brown color of photochemical smog.

Iryna Ivaniuk

Numerade Educator

01:14

Problem 54

The safety limits of ozone and carbon monoxide are $120 \mathrm{ppb}$ by volume and $9 \mathrm{ppm}$ by volume, respectively. Why does ozone have a lower limit?

Iryna Ivaniuk

Numerade Educator

05:18

Problem 55

Suggest ways to minimize the formation of photochemical smog.

Iryna Ivaniuk

Numerade Educator

03:25

Problem 56

In which region of the atmosphere is ozone beneficial? In which region is it detrimental?

Iryna Ivaniuk

Numerade Educator

03:03

Problem 57

Assume that the formation of nitrogen dioxide: $$2 \mathrm{NO}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{NO}_{2}(g)$$,is an elementary reaction. (a) Write the rate law for this reaction. (b) A sample of air at a certain temperature is contaminated with $2.0 \mathrm{ppm}$ of $\mathrm{NO}$ by volume. Under these conditions, can the rate law be simplified? If so, write the simplified rate law.
(c) Under the conditions described in (b), the halflife of the reaction has been estimated to be $6.4 \times 10^{3}$ min. What would the half-life be if the initial concentration of NO were 10 ppm?

Iryna Ivaniuk

Numerade Educator

03:53

Problem 58

The gas-phase decomposition of peroxyacetyl nitrate (PAN) obeys first-order kinetics: $$\mathrm{CH}_{3} \mathrm{COOONO}_{2} \longrightarrow \mathrm{CH}_{3} \mathrm{COOO}+\mathrm{NO}_{2}$$ with a rate constant of $4.9 \times 10^{-4} \mathrm{s}^{-1} .$ Calculate the rate of decomposition in $M / \mathrm{s}$ if the concentration of PAN is 0.55 ppm by volume. Assume STP conditions.

Iryna Ivaniuk

Numerade Educator

07:17

Problem 59

On a smoggy day in a certain city the ozone concentration was 0.42 ppm by volume. Calculate the partial pressure of ozone (in atm) and the number of ozone molecules per liter of air if the temperature and pressure were $20.0^{\circ} \mathrm{C}$ and $748 \mathrm{mmHg}$ respectively.

Iryna Ivaniuk

Numerade Educator

02:53

Problem 60

Which of the following settings is the most suitable for photochemical smog formation? (a) Gobi desert at noon in June, (b) New York City at 1 p.m. in July, (c) Boston at noon in January. Explain your choice.

Iryna Ivaniuk

Numerade Educator

03:49

Problem 61

List the major indoor pollutants and their sources.

Iryna Ivaniuk

Numerade Educator

03:45

Problem 62

What is the best way to deal with indoor pollution?

Iryna Ivaniuk

Numerade Educator

02:32

Problem 63

Why is it dangerous to idle a car's engine in a poorly ventilated place, such as the garage?

Iryna Ivaniuk

Numerade Educator

01:54

Problem 64

Describe the properties that make radon an indoor pollutant. Would radon be more hazardous if $^{222} \mathrm{Rn}$ had a longer half-life?

Iryna Ivaniuk

Numerade Educator

05:48

Problem 65

A concentration of $8.00 \times 10^{2}$ ppm by volume of CO is considered lethal to humans. Calculate the minimum mass of CO in grams that would become a lethal concentration in a closed room $17.6 \mathrm{m}$ long, $8.80 \mathrm{m}$ wide, and $2.64 \mathrm{m}$ high. The temperature and pressure are $20.0^{\circ} \mathrm{C}$ and $756 \mathrm{mm} \mathrm{Hg},$ respectively.

Iryna Ivaniuk

Numerade Educator

05:03

Problem 66

A volume of $5.0 \mathrm{L}$ of polluted air at $18.0^{\circ} \mathrm{C}$ and $747 \mathrm{mmHg}$ is passed through lime water [an aqueous suspension of $\left.\mathrm{Ca}(\mathrm{OH})_{2}\right],$ so that all the carbon dioxide present is precipitated as $\mathrm{CaCO}_{3}$. If the mass of the $\mathrm{CaCO}_{3}$ precipitate is $0.026 \mathrm{g},$ calculate the percentage by volume of $\mathrm{CO}_{2}$ in the air sample.

Iryna Ivaniuk

Numerade Educator

04:03

Problem 67

Briefly describe the harmful effects of the following substances: $\mathrm{O}_{3}, \mathrm{SO}_{2}, \mathrm{NO}_{2}, \mathrm{CO}, \mathrm{CH}_{3} \mathrm{COOONO}_{2}$ $(\mathrm{PAN}), \mathrm{Rn}$.

Iryna Ivaniuk

Numerade Educator

03:21

Problem 68

The equilibrium constant $\left(K_{P}\right)$ for the reaction $$\mathrm{N}_{2}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{NO}(g)$$ is $4.0 \times 10^{-31}$ at $25^{\circ} \mathrm{C}$ and $2.6 \times 10^{-6}$ at $1100^{\circ} \mathrm{C},$ the temperature of a running car's engine. Is this an endothermic or exothermic reaction?

Iryna Ivaniuk

Numerade Educator

03:18

Problem 69

As stated in the chapter, carbon monoxide has a much higher affinity for hemoglobin than oxygen does. (a) Write the equilibrium constant expression $\left(K_{c}\right)$ for the following process: $$\mathrm{CO}(g)+\mathrm{HbO}_{2}(a q) \rightleftharpoons \mathrm{O}_{2}(g)+\mathrm{HbCO}(a q)$$ where $\mathrm{HbO}_{2}$ and $\mathrm{HbCO}$ are oxygenated hemoglobin and carboxyhemoglobin, respectively. (b) The composition of a breath of air inhaled by a person smoking a cigarette is $1.9 \times 10^{-6} \mathrm{mol} / \mathrm{L}$ CO and $8.6 \times 10^{-3} \mathrm{mol} / \mathrm{L} \mathrm{O}_{2} .$ Calculate the ratio of $[\mathrm{HbCO}]$ to $\left[\mathrm{HbO}_{2}\right],$ given that $K_{\mathrm{c}}$ is 212 at $37^{\circ} \mathrm{C}$.

Iryna Ivaniuk

Numerade Educator

01:41

Problem 70

Instead of monitoring carbon dioxide, suggest another gas that scientists could study to substantiate the fact that $\mathrm{CO}_{2}$ concentration is steadily increasing in the atmosphere.

Iryna Ivaniuk

Numerade Educator

06:57

Problem 71

In 1991 it was discovered that nitrous oxide $\left(\mathrm{N}_{2} \mathrm{O}\right)$ is produced in the synthesis of nylon. This compound, which is released into the atmosphere, contributes both to the depletion of ozone in the stratosphere and to the greenhouse effect. (a) Write equations representing the reactions between $\mathrm{N}_{2} \mathrm{O}$ and oxygen atoms in the stratosphere to produce nitric oxide (NO), which is then oxidized by ozone to form nitrogen dioxide. (b) Is $\mathrm{N}_{2} \mathrm{O}$ a more effective greenhouse gas than carbon dioxide? Explain. (c) One of the intermediates in nylon manufacture is adipic acid $\left[\mathrm{HOOC}\left(\mathrm{CH}_{2}\right)_{4} \mathrm{COOH}\right]$ About $2.2 \times 10^{9} \mathrm{kg}$ of adipic acid are consumed every year. It is estimated that for every mole of adipic acid produced, 1 mole of $\mathrm{N}_{2} \mathrm{O}$ is generated. What is the maximum number of moles of $\mathrm{O}_{3}$ that can be destroyed as a result of this process per year?

Iryna Ivaniuk

Numerade Educator

00:01

Problem 72

A glass of water initially at $\mathrm{pH} 7.0$ is exposed to dry air at sea level at $20^{\circ} \mathrm{C}$. Calculate the pH of the water when equilibrium is reached between atmospheric $\mathrm{CO}_{2}$ and $\mathrm{CO}_{2}$ dissolved in the water, given that Henry's law constant for $\mathrm{CO}_{2}$ at $20^{\circ} \mathrm{C}$ is $0.032 \mathrm{mol} / \mathrm{L} \cdot$ atm. $(\text {Hint}:$ Assume no loss of water due to evaporation and use Table 20.1 to calculate the partial pressure of $\mathrm{CO}_{2}$. Your answer should correspond roughly to the pH of rainwater.)

Susan Hallstrom

Numerade Educator

05:12

Problem 73

A $14-\mathrm{m}$ by $10-\mathrm{m}$ by $3.0-\mathrm{m}$ basement had a high radon content. On the day the basement was sealed off from its surroundings so that no exchange of air could take place, the partial pressure of $^{222} \mathrm{Rn}$ was $1.2 \times 10^{-6} \mathrm{mmHg} .$ Calculate the number of $^{222} \mathrm{Rn}$ isotopes $\left(t_{\frac{1}{2}}=3.8 \mathrm{d}\right)$ at the beginning and end of
31 days. Assume STP conditions.

Iryna Ivaniuk

Numerade Educator

06:28

Problem 74

Ozone in the troposphere is formed by the following steps: $$\begin{array}{c}
\mathrm{NO}_{2} \longrightarrow \mathrm{NO}+\mathrm{O} \\\mathrm{O}+\mathrm{O}_{2} \longrightarrow \mathrm{O}_{3}\end{array}.$$ The first step is initiated by the absorption of visible light (NO_ is a brown gas). Calculate the longest wavelength required for step (1) at $25^{\circ} \mathrm{C}$. [Hint: You need to first calculate $\Delta H$ and hence $\Delta U$ for (1). Next, determine the wavelength for decomposing $\mathrm{NO}_{2}$ from $\Delta U .]$

Iryna Ivaniuk

Numerade Educator

02:43

Problem 75

Although the hydroxyl radical (OH) is present only in a trace amount in the troposphere, it plays a central role in its chemistry because it is a strong oxidizing agent and can react with many pollutants as well as some CFC substitutes (see p. 910). The hydroxyl radical is formed by the following reactions: $$\begin{aligned}
&\mathrm{O}_{3} \stackrel{\lambda<320 \mathrm{nm}}{\longrightarrow} \mathrm{O}^{*}+\mathrm{O}_{2}\\
&\mathrm{O}+\mathrm{H}_{2} \mathrm{O} \longrightarrow 2 \mathrm{OH}\end{aligned}$$ where $\mathrm{O}^{*}$ denotes an electronically excited atom.
(a) Explain why the concentration of $\mathrm{OH}$ is so small even though the concentrations of $\mathrm{O}_{3}$ and $\mathrm{H}_{2} \mathrm{O}$ are quite large in the troposphere. (b) What property makes OH a strong oxidizing agent? (c) The reaction between OH and $\mathrm{NO}_{2}$ contributes to acid rain. Write an equation for this process. (d) The hydroxyl radical can oxidize $\mathrm{SO}_{2}$ to $\mathrm{H}_{2} \mathrm{SO}_{4}$. The first step is the formation of a neutral $\mathrm{HSO}_{3}$ species, followed by its reaction with $\mathrm{O}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$ to form $\mathrm{H}_{2} \mathrm{SO}_{4}$ and the hydroperoxyl radical $\left(\mathrm{HO}_{2}\right) .$ Write equations for these processes.

Iryna Ivaniuk

Numerade Educator

02:45

Problem 76

The equilibrium constant $\left(K_{P}\right)$ for the reaction $$2 \mathrm{CO}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{CO}_{2}(g)$$ is $1.4 \times 10^{90}$ at $25^{\circ} \mathrm{C}$. Given this enormous value, why doesn't CO convert totally to $\mathrm{CO}_{2}$ in the troposphere?

Iryna Ivaniuk

Numerade Educator

03:14

Problem 77

A person was found dead of carbon monoxide poisoning in a well-insulated cabin. Investigation showed that he had used a blackened bucket to heat water on a butane burner. The burner was found to function properly with no leakage. Explain, with an appropriate equation, the cause of his death.

Iryna Ivaniuk

Numerade Educator

02:42

Problem 78

The carbon dioxide level in the atmosphere today is often compared with that in preindustrial days. Explain how scientists use tree rings and air trapped in polar ice to arrive at the comparison.

Iryna Ivaniuk

Numerade Educator

00:38

Problem 79

What is funny about the following cartoon?

Iryna Ivaniuk

Numerade Educator

03:03

Problem 80

Calculate the standard enthalpy of formation $\left(\Delta H_{\mathrm{f}}^{\circ}\right)$ of $\mathrm{ClO}$ from the following bond enthalpies: $\mathrm{Cl}_{2}$ :$242.7 \mathrm{kJ} / \mathrm{mol} ; \mathrm{O}_{2}: 498.7 \mathrm{kJ} / \mathrm{mol} ; \mathrm{ClO}: 206 \mathrm{kJ} / \mathrm{mol}$.

Iryna Ivaniuk

Numerade Educator

04:32

Problem 81

Methyl bromide ( $\mathrm{CH}_{3} \mathrm{Br},$ b.pt. $3.6^{\circ} \mathrm{C}$ ) is used as a soil fumigant to control insects and weeds. It is also a marine by-product. Photodissociation of the $\mathrm{C}-\mathrm{Br}$ bond produces $\mathrm{Br}$ atoms that can react with ozone similar to Cl, except more effectively. Do you expect $\mathrm{CH}_{3} \mathrm{Br}$ to be photolyzed in the troposphere? The bond enthalpy of the $\mathrm{C}-\mathrm{Br}$ bond is about 293 kJ/mol.

Iryna Ivaniuk

Numerade Educator

02:48

Problem 82

The effective incoming solar radiation per unit area on Earth is $342 \mathrm{W} / \mathrm{m}^{2}$. Of this radiation, $6.7 \mathrm{W} / \mathrm{m}^{2}$ is absorbed by $\mathrm{CO}_{2}$ at $14,993 \mathrm{nm}$ in the atmosphere. How many photons at this wavelength are absorbed per second in $1 \mathrm{m}^{2}$ by $\mathrm{CO}_{2} ?(1 \mathrm{W}=1 \mathrm{J} / \mathrm{s})$.

Iryna Ivaniuk

Numerade Educator

06:09

Problem 83

As stated in the chapter, about 50 million tons of sulfur dioxide are released into the atmosphere every year. (a) If 20 percent of the $\mathrm{SO}_{2}$ is eventually converted to $\mathrm{H}_{2} \mathrm{SO}_{4},$ calculate the number of $1000-\mathrm{lb}$ marble statues the resulting acid rain can damage. As an estimate, assume that the acid rain only destroys the surface layer of each statue, which is made up of 5 percent of its total mass. (b) What is the other undesirable result of the acid rain damage?

Iryna Ivaniuk

Numerade Educator

05:37

Problem 84

Peroxyacetyl nitrate (PAN) undergoes thermal decomposition as follows: $$\mathrm{CH}_{3}(\mathrm{CO}) \mathrm{OONO}_{2} \longrightarrow \mathrm{CH}_{3}(\mathrm{CO}) \mathrm{OO}+\mathrm{NO}_{2}$$.The rate constant is $3.0 \times 10^{-4} \mathrm{s}^{-1}$ at $25^{\circ} \mathrm{C} .$ At the boundary between the troposphere and stratosphere, where the temperature is about $-40^{\circ} \mathrm{C},$ the rate constant is reduced to $2.6 \times 10^{-7} \mathrm{s}^{-1}$. (a) Calculate the activation energy for the decomposition of $\mathrm{PAN}$ (b) What is the half-life of the reaction (in minutes) at $25^{\circ} \mathrm{C} ?$

Iryna Ivaniuk

Numerade Educator

05:23

Problem 85

How are past temperatures determined from ice cores obtained from the Artic or Antarctica? (Hint:
Look up the stable isotopes of hydrogen and oxygen. How does energy required for vaporization depend on the masses of $\mathrm{H}_{2} \mathrm{O}$ molecules containing different isotopes? How would you determine the age of an ice core?)

Adriano Chikande

Numerade Educator

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Problem 86

The balance between $\mathrm{SO}_{2}$ and $\mathrm{SO}_{3}$ is important in understanding acid rain formation in the troposphere. From the following information at $25^{\circ} \mathrm{C}$ $$\begin{aligned}\mathrm{S}(s)+\mathrm{O}_{2}(g) & \rightleftharpoons \mathrm{SO}_{2}(g) & & K_{1}=4.2 \times 10^{52} \\2 \mathrm{S}(s)+3 \mathrm{O}_{2}(g) & \rightleftharpoons 2 \mathrm{SO}_{3}(g) & & K_{2}=9.8 \times 10^{128}\end{aligned}$$.Calculate the equilibrium constant for the reaction $$2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{SO}_{3}(g)$$.
calculate the equilibrium constant for the reaction $$2 \mathrm{SO}_{2}(g)+\mathrm{O}_{2}(g) \rightleftharpoons 2 \mathrm{SO}_{3}(g)$$

Susan Hallstrom

Numerade Educator

07:05

Problem 87

Draw Lewis structures of the species in each step in the conversion of $\mathrm{SO}_{2}$ to $\mathrm{H}_{2} \mathrm{SO}_{4}$ discussed on $\mathrm{p} .917$.

Iryna Ivaniuk

Numerade Educator

01:58

Problem 88

The $\mathrm{HO}_{3}$ radical was once thought of as a temporary reservoir of atmospheric OH radicals. Draw a Lewis structure of the species.

Iryna Ivaniuk

Numerade Educator

05:06

Problem 89

What is the difference between weather and climate? In the winter months of $2010,$ record snows fell on the East Coast from Washington, D.C., to the Deep South. Can this occurrence be taken as evidence against global warming? Can you suggest one way in which global warming might actually be responsible for what happened?

Iryna Ivaniuk

Numerade Educator

02:33

Problem 90

Estimate the annual production of carbon dioxide (in kilograms) by an average passenger car in the United States.

Iryna Ivaniuk

Numerade Educator

08:58

Problem 91

The following reactions are common in the stratosphere:
(a) $\mathrm{NO}_{2}(g) \longrightarrow \mathrm{NO}(g)+\mathrm{O}(g)$
(b) $\mathrm{N}_{2} \mathrm{O}(g) \longrightarrow \mathrm{N}_{2}(g)+\mathrm{O}(g)$
(c) $\mathrm{H}_{2}(g)+\mathrm{O}(g) \longrightarrow \mathrm{OH}(g)+\mathrm{H}(g)$
(d) $\mathrm{CH}_{4}(g)+\mathrm{O}(g) \longrightarrow \mathrm{OH}(g)+\mathrm{CH}_{3}(g)$
First, without doing any calculations, predict whether each of the reactions is endothermic or exothermic. Then estimate $\Delta H^{\circ}$ for each reaction, and comment on your predictions and estimates.

Iryna Ivaniuk

Numerade Educator