Kelter P., Mosher M., Scott A. Chemistry. The Practical Science

Подождите немного. Документ загружается.

158 Chapter 4 Solution Stoichiometry and Types of Reactions

reported by the World Heath Organization in the African countries of Benin,

Burkina-Faso, Guinea, Guinea-Bissau, Mali, Mauritania, Niger, and Senegal

(Figure 4.19). In those countries that disinfect their water supply with chlorine,

however, cholera has been all but eradicated. Unfortunately, wastewater treat-

ment efﬂuent (runoff from the cities back into lakes, streams, rivers, etc.) has

resulted in chlorine concentrations between 1 and 5 parts per million. Any effect

these levels of chlorine have on the environment has yet to be determined.

The gold miners we mentioned at the start of this chapter have to be careful

with their cyanide leaching solution, because the MCLG for CN

−

is 0.200 ppm

(200 ppb). Larger quantities of this ion in water can be very harmful to the envi-

ronment. In the winter of 2000, an accidental spill in Romania resulted in ap-

proximately 22 million gallons of cyanide waste from a gold mine ﬂowing into

the nearby Tisza River. This river ﬂows into the Danube River and through Bel-

grade, Yugoslavia, on its way to the Black Sea. The initial cyanide spill killed most

of the life in the Tisza River and harmed much of the life in the Danube River. To

compound the disaster, the Tisza River is home to 17 of Hungary’s 29 protected

species of ﬁsh, including the last known species of Danube sturgeon. It will be

decades before the environment recovers from this accident.

FIGURE 4.18

The quantitative chemistry of fresh water

is a vital consideration in ensuring the

safety of our water supplies and the

health of the environment.

Maximum Contaminant Level Goal for Selected Substances in Safe Water

Potential Human

MCLG Organ Damage Due to

Substance (mg/L = ppm) Exceeding the MCLG Source

As 0.010 Skin and circulatory Runoff from orchards

system and glass-manufacturing

plants

Cd 0.005 Kidney Corrosion of pipes,

discharge from used

batteries

−

0.200 Thyroid and nerve Discharge from gold

mining, fertilizer, and

plastics manufacturing

Hg 0.002 Kidney Discharge from reﬁneries

Dioxin 0.00000003 Reproductive system By-products of smelting,

) bleaching, and pesticide

manufacture

TABLE 4.6

A water technician checks the chlorina-

tion process at a water treatment plant.

Application

The Danube sturgeon.

What must rivers and lakes contain in order to be healthful habitats for fresh-

water life?

They must contain sufﬁcient oxygen, hold appropriate quantities of

nutrients (too little or too much of these can adversely affect the water quality),

and have an appropriate acid–base balance. If pollution problems are suspected

in any river or lake, chemists and biologists must analyze the water and perhaps

also the ﬂesh and blood of ﬁsh, birds, and other organisms that live in or around

the water. Chemical water analysis includes working with measures of concentra-

tion, including parts per million, parts per billion, and molarity, and investigat-

ing each speciﬁc type of reaction that occurs in the aqueous environment.

The Bottom Line 159

■

Water is an extremely versatile solvent, partly thanks

to its polarity, which is due to the uneven distri-

bution of electrons in the molecule. (Sec-

tion 4.1)

■

When ionic compounds dissolve in water, the ions

dissociate and become surrounded by water

molecules—a process known as hydration.

(Section 4.1)

■

The concentration of a solution can be expressed

in units known as molarity. This term indicates

how many moles of the chemical concerned would

be present if we had one liter of the solution.

(Section 4.2)

Molarity =

moles of solute

liter of solution

= M

Mali

Niger

Benin

Burkina-Faso

Mauritania

Senegal

Guinea-Bissau

Guinea

FIGURE 4.19

Cholera outbreaks in 2005 were reported in many western

Africa nations.

The Bottom Line

■

Chemicals present at very low levels are often mea-

sured in terms of parts per million (ppm), parts per

billion (ppb), or parts per trillion (ppt). (Section 4.2)

■

The quantitative analysis of the chemicals present

in solutions is of great importance in medicine,

industry, and environmental science. (Sections 4.3,

4.8)

■

Precipitation reactions involve an insoluble precipi-

tate forming when soluble chemical species com-

bine. (Section 4.5)

■

Acid–base reactions involve acids and bases reacting

in ways that can neutralize the acidic and basic char-

acter of each. (Section 4.6)

■

Oxidation–reduction reactions are electron transfer

processes in which some reactants lose electrons (are

oxidized), while others gain electrons (are reduced).

(Section 4.7)

160 Chapter 4 Solution Stoichiometry and Types of Reactions

Key Words

acid A compound that produces hydrogen ions (H

)

when dissolved in water. (p. 148)

acid–base reaction The reaction between an acid and

a base. The products are water and an ionic com-

pound. (p. 148)

aqueous Water-based; also implies that a dissolved sub-

stance has a sphere of hydration. (p. 126)

base A compound that produces hydroxide ions (OH

−

)

when dissolved in water. (p. 148)

buret A laboratory device used to precisely and accu-

rately add small known quantities of solution.

(p. 140)

complete ionic equation A chemical equation that indi-

cates all of the ions present in a reaction as individual

entities. (p. 144)

concentration An intensive property of a solution that

describes the amount of solute dissolved per volume

of solution or solvent. The typical concentration

units include molarity, ppm, and w/w. (p. 131)

diprotic Can produce 2 mol of H

when it dissolves.

(p. 151)

electrolyte A compound that produces ions when dis-

solved in water. (p. 129)

end point In a titration, the volume of the added reac-

tant that causes a visual change in the color of the

indicator. (p. 140)

equivalence point In a titration, the point at which all re-

actants have just been completely consumed. (p. 140)

half-reaction An incomplete equation that describes the

oxidation or reduction portion of a redox reaction.

(p. 153)

hydration sphere The shell of water molecules surround-

ing a dissolved molecule, ion, or other compound.

This shell arises because of the force of attraction be-

tween the water molecules and the solute. (p. 127)

insoluble Not capable of dissolving in a solvent to an

appreciable extent. (p. 145)

molar (M) The “shorthand” method of describing mo-

larity, as in “that is a 3 molar HCl solution.”

(p. 132)

molarity (M) A speciﬁc concentration term that reﬂects

the moles of solute dissolved per liter of total solu-

tion. (p. 131)

molecular equation A chemical equation that shows

complete molecules and compounds. (p. 144)

monoprotic Can produce 1 mol of H

when it dissoci-

ates. (p. 151)

net ionic equation A complete ionic equation written

without the spectator ions. (p. 144)

nonelectrolyte A compound that doesn’t dissociate into

ions when it dissolves. (p. 129)

oxidation The process of losing electrons. Such a sub-

stance is said to be oxidized. (p. 152)

oxidation number A “bookkeeping” number that reﬂects

the charge on an ion. (p. 154)

oxidation–reduction reactions Reactions that involve the

transfer of electrons from one species to another.

Also known as redox reactions. (p. 153)

oxidation state See oxidation number. (p. 154)

oxidized The species that has lost electrons in a redox

reaction. (p. 152)

parts per billion (ppb) One gram of solute per billion

grams of solution. (p. 135)

parts per million (ppm) One gram of solute per million

grams of solution. (p. 135)

parts per trillion (ppt) One gram of solute per trillion

grams of solution. (p. 135)

precipitation reaction A reaction involving the formation

of a solid that isn’t soluble in the reaction solvent.

(p. 146)

precipitate Any solid material that forms within a solu-

tion; the action describing the formation of a solid.

(p. 145)

redox reactions See oxidation–reduction reactions.

(p. 153)

reduced The species that has gained electrons in a redox

reaction. (p. 152)

reduction The process of gaining electrons. Such a sub-

stance is said to be reduced. (p. 152)

soluble The ability of a substance to dissolve within a

solution. (p. 145)

solutes Molecules, ions, or atoms that are dissolved in a

solvent to form a solution. (p. 126)

solution (Deﬁned in Chapter 2.) A homogeneous mix-

ture of solute and solvent. (p. 126)

solvent A compound that typically makes up the ma-

jority of a homogeneous mixture of molecules, ions,

or atoms; dissolves the solute. (p. 126)

spectator ions Ions that do not participate in a reaction.

(p. 144)

strong acid An acid that completely dissociates in solu-

tion. (p. 149)

strong base A base that completely dissociates in solu-

tion. (p. 149)

strong electrolyte Any compound that completely disso-

ciates in solution. (p. 129)

standard solution A solution with a well-deﬁned and

known concentration of solute. (p. 140)

titration The process of adding one reactant to an un-

known amount of another until the reaction is com-

plete; used to determine the concentration of an

unknown solute. (p. 140)

triprotic Can produce 3 mol of H

when it dissolves.

(p. 151)

weak acid An acid that partially dissociates in solution.

(p. 150)

weak base A base that partially dissociates in solution.

(p. 150)

weak electrolyte Any substance that only partially disso-

ciates in solution. (p. 129)

Focus Your Learning 161

Focus Your Learning

The answers to the odd-numbered problems and some selected

problems appear at the back of the book, as represented by the

blue numbering.

Section 4.1 Water—A Most Versatile Solvent

Skill Review

1. Explain how water molecules can dissolve both cations and

anions.

2. Why doesn’t pure water conduct an electric current?

3. Explain what is meant by the term hydration sphere?

4. Diagram, using circles for atoms, a crystal of KCl versus the

same crystal of KCl dissolved in water.

Chemical Applications and Practices

5. Earth’s oceans contain tons of dissolved sodium chloride.Yet,

when a ship develops an oil leak, almost none of the oil dis-

solves in the ocean. Explain this phenomenon.

6. When an ion dissolves, it is surrounded by a hydration

sphere. If water molecules surrounded the ion so that the hy-

drogen portion of the water was closer to the ion, would the

ion most likely be a cation or an anion?

7. Pure water does not conduct an electric current. However,

aqueous solutions of some compounds do form solutions

that conduct electricity. Explain why the presence of some

solutes converts nonconducting water into a conducting

solution.

8. Glycerin can be produced as a by-product in soap making.

The compound dissolves so easily in water that it absorbs

water from the air. This latter characteristic is why glycerin

is often found in many skin lotions. As glycerin absorbs

the water, the skin can be kept moist. Glycerin’s structure is

shown below. What aspects of glycerin’s structure contribute

most to its ease of dissolving in water?

9. A conductivity-testing apparatus, such as the one shown in

this chapter, possesses a light bulb whose brightness is related

to how much current is ﬂowing through it (and also through

the solution.) A small, but measurable, amount of current

must be present before the bulb becomes visibly brighter.

What effect would this characteristic of the apparatus have

on the classiﬁcation of solutions containing strong elec-

trolytes, containing weak electrolytes, and containing non-

electrolytes?

10. When dissolved in water, which of the following would you

expect to cause a conductivity tester, shown in the chapter, to

produce a very bright light? (Assume that 0.50 mole of each

is placed in 1.0 L of solution.)

a. C

OH (ethanol) d. KCl

b. NaOH e. BaSO

c. Na

Section 4.2 The Concentration of Solutions

Skill Review

11. Which of the following would best represent MgCl

dissolved

in water?

12. Which of the following would best represent H

dissolved in

water?

13. If 0.100 mol MgCl

is dissolved in water, how many total

moles of ions are there in the resulting solution?

14. If 0.100 mol H

is dissolved in water, how many total moles of

ions are there in the resulting solution?

CHH

cerin

(a) (b)

OCl

–

(a) (b)

162 Chapter 4 Solution Stoichiometry and Types of Reactions

25. Determine the concentration, in ppm, for each of the follow-

ing solutions.

a. 2.5 mg NaCl per 1000.0 L solution

b. 5.25 mg Cu

ions per 500.0 mL solution

c. 12.5 mg Cl

−

ions per 300.0 mL solution

26. Determine the concentration, in ppm, for each of the follow-

ing solutions.

a. 1.20 mg KCl per 1000.0 mL solution

b. 0.100 g Co

ions per 500.0 mL solution

c. 1.00 micrograms CN

−

ions per 450.0 mL solution

27. Perform the indicated conversions.

a. 1.20 × 10

−4

M NaCl to ppm

b. 5.33 ppm CN

−

to ppb

c. 170 ppm NaOH to mass percent

28. Perform the indicated conversions.

a. 0.00250 M CuCl

to mass percent

b. 19 ppm CN

−

to M

c. 0.0011% NaOH by mass to M

Chemical Applications and Practices

29. When growing certain bacteria, biologists must often control

the acidity level of the growth medium. To do this, a variety

of compounds, referred to as buffer systems, may be added in

speciﬁc amounts. Which of the following has the greater

molarity?

a. 42.0 g of KH

dissolved in 250.0 mL of solution

b. 21.0 g of KH

dissolved in 125.0 mL of solution

30. If a student seeking to prepare a 1.0 M solution of KOH

added 56 g of solid KOH to exactly 1.0 L of water, would the

solution be greater or less than 1.0 M? Explain the basis of

your conclusion.

31. Adding antifreeze to aqueous automobile cooling systems

lowers the freezing point of the resulting solution. The main

ingredient in most antifreeze products is ethylene glycol

). How many kilograms of ethylene glycol are dis-

solved in a 10.0-liter solution that is 16.0 M?

32. Oxygen dissolved in water is critical for aquatic life. The level

of dissolved oxygen is often used to report the quality of

water in the environment. If 0.0090 g of O

is dissolved per

liter of solution, what would be reported as (a) the molarity,

and (b) the concentration in ppm, of dissolved oxygen?

33. Occasionally students enjoy a cup of coffee or tea while

studying chemistry. The amount of caffeine in those bever-

ages varies greatly. At a temperature of 65°C, the maximum

amount of caffeine (C

) that can be dissolved in

water is 455g/L. What would be the maximum molarity of

caffeine in a 425-mL cup of 65°C coffee?

34. The compound potassium permanganate forms intensely

purple solutions that are used to react with other solutions

that contain iron. How many grams of potassium perman-

ganate (KMnO

) would you need to dissolve into 0.500 L of

solution if you wanted to prepare a 0.00100 M solution of

KMnO

35. The pesticide atrazine (C

Cl) is so slightly soluble in

water that its concentration is not usually reported in molar-

ity. Health advisory warnings are issued if the atrazine con-

centration is higher than 3.0 parts per billion. How many

15. The formula of vitamin C is C

. Calculate the molarity

of each of the following vitamin C solutions:

a. 0.150 g of vitamin C dissolved in enough water to produce

a 1.50 L solution

b. 0.250 g of vitamin C dissolved in enough water to produce

a 0.500 L solution

c. 3.50 g of vitamin C dissolved in enough water to produce

a 2.0 L solution

16. The formula of ethanol is C

O. Calculate the molarity of

each of the following ethanol solutions:

a. 0.150 g of ethanol dissolved in enough water to produce a

1.50 L solution

b. 25 g of ethanol dissolved in enough water to produce a

0.500 L solution

c. 100 g of ethanol dissolved in enough water to produce a

2.0 L solution

17. Determine the mass of glycine (C

) in each of the

following solutions:

a. 100.0 mL of 0.015 M glycine

b. 125.0 mL of 0.0145 M glycine

c. 74.6 mL of 1.44 M glycine

18. Determine the volume of solution needed to provide the

following amounts:

a. 4.50 g ethanol (C

O) from a 2.50 M ethanol solution

b. 63.7 g HCl from a 6.0 M HCl solution

c. 3.0 g glucose (C

) from a 0.150 M solution

19. Calculate the molarity of

a. calcium ions in 1.00 L of solution containing 24.55 g of

calcium chloride

b. chloride ions in 1.00 L of solution containing 24.55 g of

calcium chloride

c. water in pure water

20. Calculate the molarity of

a. HBr if 45.0 g is dissolved in 1.0 L.

b. NaOH if 32.5 g is dissolved in 500 mL

c. chloride ions in a 5.0 L solution containing 2.00 g NaCl.

21. One important source of bromine, in the form of Br

−

(aq), is

seawater. If the molarity of Br

−

in seawater is approximately

0.00081 M, how many liters of seawater would be required to

obtain 1 mole of Br

−

22. Chloride can be obtained from seawater. If the molarity of

−

in seawater is approximately 0.522 M, how many liters of

seawater would be required to obtain 1 mole of Cl

−

23. Determine the volume of a 0.125 M solution of MgCl

needed to provide

a. 0.10 mol MgCl

b. 0.10 mol Mg

c. 2.33 mol Cl

−

24. Determine the volume of a 0.0357 M solution of Na

needed to provide

a. 0.10 mol Na

b. 0.10 mol Na

c. 4.30 mol SO

2−

Focus Your Learning 163

43. First complete the following reaction using words rather than

chemical symbols. Then write the molecular, complete ionic,

and net ionic equations that describe this aqueous solution

reaction.

Potassium hydroxide + hydrochloric acid →

44. List the spectator ions for the following reaction:

Sulfuric acid + potassium hydroxide →

45. Write the molecular, complete ionic, and net ionic equations

for the following reaction:

Sodium chloride + calcium nitrate

→ sodium nitrate +calcium chloride

46. Write the molecular, complete ionic, and net ionic equations

for the following reaction:

Magnesium chloride + sodium bromide

→ sodium chloride +magnesium bromide

Chemical Applications and Practices

47. Using the stoichiometry found in the chapter for the vita-

min C and I

reaction, determine which of the following two

drinks contains the greater concentration of vitamin C.

Which sample contains the greater amount of vitamin C?

a. Brand A: 250.0 mL solution required 10.5 mL of

0.0855 M I

b. Brand B: 300.0 mL solution required 12.0 mL of

0.0855 M I

48. Using the stoichiometry found in the chapter for the vita-

min C and I

reaction, determine which of the following two

drinks contains the greater concentration of vitamin C.

Which sample contains the greater amount of vitamin C?

a. Brand A: 150.0 mL solution required 8.5 mL of

0.0650 M I

b. Brand B: 100.0 mL solution required 12.5 mL of

0.0250 M I

49. One of the more common agents for standardizing solutions

of sodium hydroxide (NaOH) is potassium acid phthalate

(KHC

), or, more accurately, potassium hydrogen

phthalate. The compound is often abbreviated KHP, where

the P designates the phthalate ion (C

2−

), not the phos-

phorus atom. From the following data, determine the average

molarity of a NaOH solution that was standardized with

KHP.

Trial A: 45.12 mL of NaOH solution neutralized 0.5467 g

of KHP

Trial B: 44.89 mL of NaOH solution neutralized 0.5475 g

of KHP

Trial C: 46.50 mL of NaOH solution neutralized 0.5501 g

of KHP

50. One of the more common agents for standardizing solutions

of potassium hydroxide (KOH) is potassium acid phthalate

(KHC

), or, more accurately, potassium hydrogen

phthalate. From the following data, determine the average

molarity of a KOH solution that was standardized with KHP.

Trial A: 45.12 mL of KOH solution neutralized 0.2573 g

of KHP

Trial B: 48.89 mL of KOH solution neutralized 0.2250 g

of KHP

Trial C: 45.50 mL of KOH solution neutralized 0.2502 g

of KHP

grams of atrazine would you expect to ﬁnd in 1 L of water

that is 3.0 ppb in atrazine? What would be the molarity of the

solution?

36. A can of nondiet soda may contain 45 g of sucrose

) per 450 g of soda. What is the sugar concentra-

tion reported as ppm? Approximately how many grams of

water would you have to add to the soda to reduce this sugar

concentration to only 1 part per million?

37. A certain sports drink has a NaCl concentration of 0.20 M.If

the container held 250 mL of the liquid, how many moles of

would you consume when swallowing 50.0 mL of the

drink?

38. One method used to detect the presence of the toxic heavy

metal barium is to precipitate the barium +2 ion as barium

sulfate. If a 10.0-mL sample produced 0.565 g of barium sul-

fate (and assuming that no more Ba

remained dissolved)

what was the original molarity of Ba

in the solution?

Section 4.3 Stoichiometric Analysis of Solutions

Skill Review

39. Assume 1:1 reaction stoichiometry in each of the following:

a. 25.0 mL of HCl required 35.0 mL of 0.155 M NaOH to

neutralize. What is the molarity of the HCl solution?

b. 50.0 mL of Sr(OH)

required 35.0 mL of 0.0200 M sulfuric

acid to neutralize. What is the molarity of the Sr(OH)

solution?

c. 40.5 mL of niric acid (HNO

) required 25.0 mL of 0.35 M

KOH to neutralize. What is the molarity of the HNO

solution?

40. Assume 1:1 reaction stoichiometry in each of the following:

a. 33.0 mL of HCl required 17.6 mL of 2.50 M NaOH to

neutralize. What is the molarity of the HCl solution?

b. 10.25 mL of Sr(OH)

required 15.56 mL of 0.00150 M

sulfuric acid to neutralize. What is the molarity of the

Sr(OH)

solution?

c. 100.0 mL of nitric acid (HNO

) required 84.30 mL of

1.562 × 10

−4

M KOH to neutralize. What is the molarity

of the HNO

solution?

41. The label on a solution was partially obscured. It was either

0.10 M CuCl or 0.10 M CuCl

. When the entire 25.0 mL of

the solution was evaporated to dryness, 0.336 g of solid re-

mained. What should the label read?

42. The label on a solution was partially obscured. It was either

0.10 M FeCl

or 0.10 M FeCl

. If the solution was actually

0.10 M FeCl

, how many grams of FeCl

would be obtained if

100.0 mL of the solution were evaporated to dryness?

N N

Atrazine

51. Hydrochloric acid has many industrial uses. The steel indus-

try uses hydrochloric acid in a process known as “pickling

steel.” This is done to steel prior to galvanizing. To analyze

the concentration of the “pickle liquor,” a titration with

sodium hydroxide may be used. Write the net ionic reaction

between hydrochloric acid and sodium hydroxide, and then

determine the concentration of the HCl in the pickling

liquor if a 10.00 mL sample of the hydrochloric acid re-

quired 45.55 mL of a 0.9876 M solution of NaOH to com-

pletely react.

52. Nitrogen for increased yields on farms can come from a vari-

ety of sources. One common nitrogen-containing fertilizer

is ammonium sulfate, (NH

)

. The reaction between

ammonia (NH

) and sulfuric acid (H

) produces this

important fertilizer.

a. Balance the reaction.

b. How many liters of a 1.55 M solution of sulfuric acid

would be needed to completely react with 1.00 kg of

ammonia?

53. One method that ﬁeld geologists use to test for the presence

of carbonates is to drip hydrochloric acid on a sample and

note the formation of carbon dioxide gas bubbles.

a. Balance the reaction between calcium carbonate (CaCO

)

and hydrochloric acid (HCl.)

b. If 5.00 mL of 0.500 M HCl completely reacted with

calcium carbonate in a rock sample, how many grams

of calcium carbonate did the sample contain?

54. Hydrogen peroxide, in very dilute concentrations, can be

used as a disinfectant. The concentration of hydrogen perox-

ide (H

) can be determined in a titration experiment using

potassium permanganate (KMnO

) as shown in the follow-

ing balanced equation:

2MnO

−

(aq) + 5H

(aq) + 6H

(aq)

→ 5O

(g) + 2Mn

(aq) + 8H

O(l)

If a 25.0 mL sample of hydrogen peroxide required 25.2 mL

of 0.353 M KMnO

solution to react with all the hydrogen

peroxide, what was the molarity of the hydrogen peroxide

solution?

Section 4.4 Types of Chemical Reactions

Skill Review

55. Predict the products of the following incomplete reactions.

After balancing the reaction, label each as a precipitation,

acid–base, or redox reaction. For those reactions where it is

possible, write the net ionic equation.

a. C

(g) + O

(g) →

b. Ca(OH)

(aq) + HNO

(aq) →

c. Pb(NO

)

(aq) + NaCl(aq) →

56. Predict the products of the following incomplete reactions.

After balancing the reaction, label each as a precipitation,

acid–base, or redox reaction. For those reactions where it is

possible, write the net ionic equation:

a. HCl(g) + Ca(OH)

(aq) →

b. CH

(g) + O

(aq) →

c. Ba(ClO

)

(aq) + Na

S(aq) →

164 Chapter 4 Solution Stoichiometry and Types of Reactions

Section 4.5 Precipitation Reactions

Skill Review

57. Which of the following salts would qualify as soluble in

water?

a. CuCO

d. KOH

b. NiS e. lead acetate

c. (NH

)

58. Which of the following salts would qualify as soluble in

water?

a. NaNO

d. PbBr

b. Ba(OH)

e. AgI

c. MgSO

59. Predict the products and write the net ionic equations for

each of the following:

a. BaCl

(aq) + NaNO

(aq) →

b. Fe(NO

)

(aq) + (NH

)

(aq) →

c. CaCl

(aq) + K

(aq) →

60. Predict the products and write the net ionic equations for

each of the following:

a. MgCl

(aq) + KNO

(aq) →

b. AgNO

(aq) + NH

Cl(aq) →

c. CaCl

(aq) + NaOH(aq) →

61. Write out the formulas of each of the following reactants.

Then predict the result of mixing the aqueous solutions for

each situation. Finally, report the net ionic equation for each.

a. Copper(II) nitrate + potassium hydroxide →

b. Sodium carbonate + aluminum chloride →

c. Ammonium phosphate + zinc chloride →

62. Write out the formulas of each of the following reactants.

Then predict the result of mixing the aqueous solutions for

each situation. Finally, report the net ionic equation for each.

a. Barium nitrate + sodium hydroxide →

b. Ammonium carbonate + aluminum bromide →

c. Silver nitrate + zinc bromide →

63. Name two soluble ionic compounds that could be used to

produce each of the following insoluble salts:

a. BaS b. Cu(OH)

c. PbSO

64. Name two soluble ionic compounds that could be used to

produce each of the following insoluble salts:

a. AgBr b. Fe(OH)

c. PbS

Chemical Applications and Practices

65. Suppose you have a water sample that is to be analyzed. You

know the sample contains Cu

,Ba

, and Ag

ions. Suggest

a sequence for adding other aqueous electrolyte solutions

that could separate each of these by selective precipitation.

66. The presence of metal ions in aqueous systems can often

cause environmental complications. Suppose it was neces-

sary to remove Cu

ions from a sample of water. Suggest at

least two reagents that you could add to the aqueous system

to remove the copper ions.

67. A traditional method for the analysis of dissolved ions is

called gravimetric analysis. This name is derived from the

process in which the ion to be analyzed is precipitated and

ﬁltered as gravity separates the liquid from the precipitate.

Suppose that you found that all the silver ion (Ag

) in a solu-

tion, present as AgNO

(aq), reacted with 25.0 mL of 0.242 M

NaCl to form solid AgCl.

a. Write the molecular and net ionic equations for the

precipitate formation.

b. Determine the grams of precipitate formed and the

grams of silver present in the original solution.

68. One method of preparing the compound AgBr, used in pho-

tographic ﬁlms, is to precipitate it from a solution of KBr.

After ﬁrst writing and balancing the molecular and net ionic

equations, calculate many grams of AgBr precipitate when

100.0 mL of 2.00 M KBr is mixed with 100.0 mL of 1.00 M

AgNO

Section 4.6 Acid–Base Reactions

Skill Review

69. What is the net ionic reaction of the following acid–base re-

action? You’ll have to provide the balanced molecular equa-

tion in order to begin this problem.

Hydrogen bromide + magnesium hydroxide

→ water + magnesium bromide

70. What acid–base reaction would produce each of the follow-

ing salts? Write the balanced chemical equation in each case.

a. NaCl b. K

c. Na

d. Al(NO

)

71. a. What would be the molarity of a KOH solution if, during a

titration with 0.50 M HCl, 34.5 mL of the HCl neutralized

22.4 mL of the KOH solution?

b. How much of a 0.50 M solution of H

would be

needed to neutralize the same amount of the KOH

solution?

72. If a student mixes 25.0 mL of 0.255 M H

with 50.0 mL of

0.115 M KOH (assume the volumes are additive), which

reagent will be in excess? What will be the concentration of

the excess reagent?

Chemical Applications and Practices

73. Oxalic acid can be found in rhubarb plants. If a 0.255-g sam-

ple of puriﬁed oxalic acid required 25.7 mL of NaOH to neu-

tralize, what would you report as the molarity of the NaOH

solution? (Oxalic acid: H

)

74. Phosphoric acid is a very versatile acid with widespread uses,

from making fertilizer to soft drink ingredients.

a. Balance the reaction between phosphoric acid (H

)

and ammonium hydroxide (NH

OH).

b. How many milliliters of 0.459 M ammonium hydroxide

would be needed to neutralize 33.5 mL of 0.100 M

phosphoric acid?

75. Carbonic acid is formed when gaseous carbon dioxide is

pumped into soft drinks to establish their carbonation. Sup-

pose you are employed at the new “ChemCola” beverage

company. You must titrate the carbonic acid in the soft drink

using 0.1445 M NaOH.

Focus Your Learning

165

a. Write the molecular and net ionic equations.

b. What is the molarity of carbonic acid if a 50.00 mL sample

required 38.98 mL of 0.1445 M NaOH?

76. Acetic acid is the ingredient in vinegar that gives it its vine-

gary taste and smell. If a particular brand claims to be 5.00%,

by mass, acetic acid (HC

), how many milliliters of

0.255 M NaOH would be required to neutralize the acetic

acid in a 25.0 mL vinegar sample?

77. Stomach acid (HCl) is neutralized by a variety of commercial

antacids. For each of the following, determine how many

grams of active antacid ingredient would be necessary to

neutralize the HCl in 50.00 mL of 0.0100 M HCl (an approx-

imation of the concentration of HCl in the stomach).

a. Al(OH)

b. Mg(OH)

c. CaCO

78. Sulfuric acid is the acid ingredient in automobile battery acid

solutions. The sulfuric acid content of such a solution can be

determined through a lab analysis by reacting it in a titration

with potassium hydroxide. The unbalanced reaction is

(aq) + KOH(aq) → K

(aq) + H

O(l)

Use the balanced reaction to ﬁll in the missing data in the

following table.

Molarity Volume Molarity Volume

of H

of KOH KOH

(M) (mL) (M) (mL)

0.25 75.0 28.6

28.9 0.36 35.8

0.88 1.11 27.5

1.76 22.0 49.7

Section 4.7 Oxidation–Reduction Reactions

Skill Review

79. In a compound made up only of each of the following pairs

of elements, select the atom that is more likely to carry a neg-

ative or slightly negative charge.

a. C, H d. P, Fe

b. O, F e. Ca, O

c. Na, O

80. In a compound made up only of each of the following pairs

of elements, select the atom that is more likely to carry a neg-

ative or slightly negative charge.

a. K, H d. N, Ca

b. Li, F e. N, Mg

c. Na, S

81. Assign oxidation numbers to all the elements in each of the

following molecules or ions:

a. N

d. N

b. PO

3−

e. H

c. CuCO

Carbonic acid

82. Assign oxidation numbers to all the elements in each of the

following molecules or ions:

a. CH

c. KHCO

e. KMnO

b. SO

2−

d. Na

Chemical Applications and Practices

83. The following balanced equation depicts a reaction that can

be used for the determination of iron in a steel sample. Is this

a redox reaction? Prove it by showing which elements change

oxidation state.

6Fe

(aq) + 14H

(aq) + Cr

2−

(aq)

→ 6Fe

(aq) + 2Cr

(aq) + 7H

O(l)

84. The following reaction depicts one of the steps in obtaining

the important steel alloying ingredient titanium.

TiCl

+ 2Mg → Ti + 2MgCl

a. Identify the substance being oxidized.

b. Identify the substance being reduced.

Comprehensive Problems

85. Why is water called the universal solvent?

86. An interesting demonstration often used by chemistry teach-

ers utilizes several of the principles that you have been reading

about in this chapter. First, a solution of barium hydroxide is

shown to conduct electricity by having the electrodes from a

conductivity tester immersed in the solution and observing

that a light begins to shine. Then a solution of sulfuric acid is

slowly added.A white precipitate begins to form,and the light

bulb dims. Eventually, the addition of the sulfuric acid causes

the bulb to go out. Finally, continued addition of the sulfuric

acid solution brings the bulb back on to bright light.

a. What is the identity of the white precipitate?

b. What is the net ionic equation for the reaction between

barium hydroxide and sulfuric acid?

c. What is the signiﬁcance of the point at which the bulb

goes out completely?

d. Explain why continued addition of the sulfuric acid

causes the light to come back on.

87. Some chemical reactions are best done in solution. If you had

100.0 mL of 0.230 M NaOH, how many milliliters of 0.530 M

HCl would you need to have the same number of moles as

found in the NaOH solution?

88. Extreme ozone pollution is described as any concentration

greater than 0.28 ppm ozone, C, O

. If the density of a sample

of air containing that concentration of ozone were 1.30 g/L,

what would be the molarity of ozone in the sample? How

many molecules of ozone would be in 1 L of the air?

89. Using Table 4.3, determine the identity and formula of any

and all precipitates that are likely to form when a solution

containing NaOH and (NH

)

is mixed with a solution

that contains CuNO

and BaCl

90. a. An unlabeled solution may contain either Ag

ions or Al

ions. Using Table 4.3, determine a suitable anion solution

that, through selective precipitation, could be added to

identify the cation present in the solution.

b. Another unlabeled solution contains either nitrate ions

or sulfate ions. Using Table 4.3, determine a solution that

166 Chapter 4 Solution Stoichiometry and Types of Reactions

contains a cation that could be used in a selective precipi-

tation to determine the identity of the anion in the unla-

beled solution.

91. Barium-containing “milkshakes” are often used to obtain

X-rays of patients suffering from intestinal problems. Bar-

ium compounds can also be toxic. Barium sulfate is insoluble

in water, so it can be given to patients without concern that it

would be absorbed. It is also opaque to X-rays. Write the

molecular and ionic balanced equations for the formation of

BaSO

(s) from Ba(NO

)

(aq) and Na

(aq). How many

grams could be obtained from mixing 125.0 mL of 0.567 M

(aq) and 75.0 mL of 0.786 M Ba(NO

)

(aq)?

92. The reaction of gaseous dinitrogen trioxide with water can

provide aqueous nitrous acid as the product.

a. Write the balanced chemical reaction.

b. If 12.5 grams of dinitrogen trioxide treated with excess

water produced 12.5 grams of nitrous acid, what is the

percent yield of the reaction?

c. To make the nitrous acid as described in part b, the

dinitrogen trioxide was bubbled into 1.55 gallons of

water. Assuming that the amount of water remains

constant during the reaction, what is the concentration

of nitrous acid after the reaction?

93. A chef wishes to make a very lightly sweetened tea by dissolv-

ing 1.00 g fructose (C

) in 12 ﬂuid ounces of tea.

a. What is the concentration of fructose in the tea in

molarity?

b. What is the concentration of fructose in ppm?

c. How many carbon atoms are there in 1.00 g of fructose?

d. How many water molecules are in the serving of tea?

Thinking Beyond the Calculation

94. Oxalic acid can be found in a variety of plants. This com-

pound is considered toxic. Therefore, it is often important

to determine the quantity in a sample. This can be done

through a redox titration.

2−

(aq) + 16H

(aq) + 2MnO

−

(aq)

→ 2Mn

(aq) + 10CO

(g) + 8H

O(l)

a. Judging on the basis of the

structure of oxalic acid shown

here, would you expect it to be

soluble or insoluble in water?

b. Write equations that illustrate the

dissolution and dissociation of

oxalic acid in water.

c. Which of the species in the bal-

anced redox reaction above is

more oxidized, oxalate (C

2−

)

or carbon dioxide?

d. Which of the species in the balanced redox reaction is

more oxidized, permanganate or manganese ions?

e. How many electrons are being transferred among the

reactants in the balanced redox reaction?

f. Determine which species is oxidized, and which is re-

duced, in the balanced redox reaction.

g. If a properly prepared plant sample required 33.5 mL of a

0.00976 M KMnO

solution to react, calculate the

number of grams of oxalic acid (H

) present.

Oxalic acid

167

Energy

The space shuttle lifts off from its

launch pad in Florida. The tremen-

dous amount of energy released by

the chemical reactions in the solid

rocket boosters and main engine

results in a force strong enough to

oppose the force of gravity acting

on the shuttle.

167

Contents and Selected Applications

Chemical Encounters: Setting the Stage with the Space Shuttle

5.1 The Concept of Energy

5.2 Keeping Track of Energy

Chemical Encounters: Energy in Foods

5.3 Speciﬁc Heat Capacity and Heat Capacity

5.4 Enthalpy

5.5 Hess’s Law

Chemical Encounters: Focus on Methane

5.6 Energy Choices

Chemical Encounters: Energy Choices

Go to college.hmco.com/pic/kelterMEE for online learning resources.