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General Chemistry

Darrell Ebbing, Steven D. Gammon

Chapter 12

Solutions - all with Video Answers

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Chapter Questions

01:36

Problem 1

Give one example of each: a gaseous solution, a liquid solution, a solid solution.

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02:40

Problem 2

What are the two factors needed to explain the differences in solubilities of substances?

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02:36

Problem 3

Explain in terms of intermolecular attractions why octane is immiscible in water.

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02:01

Problem 4

Explain why ionic substances show a wide range of solubilities in water.

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01:57

Problem 5

Using the concept of hydration, describe the process of dissolving a sodium chloride crystal in water.

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01:40

Problem 6

What is the usual solubility behavior of an ionic compound in water when the temperature is raised? Give an example of an exception to this behavior.

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01:36

Problem 7

Give one example of each: a salt whose heat of solution is exothermic and a salt whose heat of solution is endothermic.

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01:34

Problem 8

What do you expect to happen to a concentration of dissolved gas in a solution as the solution is heated?

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01:48

Problem 9

Explain why a carbonated beverage must be stored in a closed container.

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02:01

Problem 10

Pressure has an effect on the solubility of oxygen in water but a negligible effect on the solubility of sugar in water. Why?

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02:10

Problem 11

Four ways were discussed to express the concentration of a solute in solution. Identify them and define each concentration unit.

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04:58

Problem 12

When two beakers containing different concentrations of a solute in water are placed in a closed cabinet for a time, one

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02:14

Problem 13

Explain the process of fractional distillation to separate a solution of two liquids into pure components.

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01:36

Problem 14

Explain why the boiling point of a solution containing a nonvolatile solute is higher than the boiling point of a pure solvent.

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01:51

Problem 15

List two applications of freezing-point depression.

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02:18

Problem 16

Explain the process of reverse osmosis to produce drinkable water from ocean water.

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02:07

Problem 17

One can often see "sunbeams" passing through the less dense portions of clouds. What is the explanation for this?

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01:25

Problem 18

Give an example of an aerosol, a foam, an emulsion, a sol, and a gel.

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02:18

Problem 19

Explain on the basis that "like dissolves like" why glycerol, $\mathrm{CH}_{2} \mathrm{OHCHOHCH}_{2} \mathrm{OH}$, is miscible in water but benzene, $\mathrm{C}_{6} \mathrm{H}_{6}$, has very limited solubility in water.

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01:50

Problem 20

Explain how soap removes oil from a fabric.

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01:56

Problem 21

Calculate the number of moles of barium chloride in $427 \mathrm{~g}$ of a $3.17 \%$ by mass barium chloride solution?
a. $6.50 \times 10^{-02}$ mol
b. $7.83 \times 10^{-02}$ mol
c. $4.31 \times 10^{-02}$ mol
d. $7.81 \times 10^{-02}$ mol
e. $4.27 \times 10^{-02} \mathrm{~mol}$

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03:07

Problem 22

The mole fraction of copper(II) nitrate in an aqueous copper(II) nitrate solution is $0.135 .$ What is the molality of the copper(II) nitrate solution?
a. $7.49 \mathrm{~m}$
b. $8.01 \mathrm{~m}$
C. $8.66 \mathrm{~m}$
d. $9.34 \mathrm{~m}$
e. $8.09 \mathrm{~m}$

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02:27

Problem 23

If $291 \mathrm{~g}$ of a compound is added to $1.02 \mathrm{~kg}$ of water to increase the boiling point by $5.77^{\circ} \mathrm{C}$, what is the molar mass of the added compound? (Assume a van't Hoff factor of $1 .$ )
a. $31.1 \mathrm{~g} / \mathrm{mol}$
b. $30.3 \mathrm{~g} / \mathrm{mol}$
c. $28.5 \mathrm{~g} / \mathrm{mol}$
d. $18.3 \mathrm{~g} / \mathrm{mol}$
e. $25.3 \mathrm{~g} / \mathrm{mol}$

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01:24

Problem 24

A 5.1-g sample of $\mathrm{CaCl}_{2}$ is dissolved in a beaker of water. Which of the following statements is true of this solution?
a. The solution will freeze at a lower temperature than pure water.
b. The solution has a higher vapor pressure than pure water.
c. The solution will boil at a lower temperature than pure Water.
d. Water is the solute in this solution.
e. None of the other statements $(\mathrm{a}-\mathrm{d})$ are true.

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07:44

Problem 25

Consider two hypothetical pure substances, $\mathrm{AB}(s)$ and $\mathrm{XY}(s) .$ When equal molar amounts of these substances are placed in separate $500-\mathrm{mL}$ samples of water, they undergo the following reactions:
$$\begin{gathered}\mathrm{AB}(s) \longrightarrow \mathrm{A}^{+}(a q)+\mathrm{B}^{-}(a q) \\
\mathrm{XY}(s) \longrightarrow \mathrm{XY}(a q)
\end{gathered}$$
a. Which solution would you expect to have the lower boiling point? Why?
b. Would you expect the vapor pressures of the two solutions to be equal? If not, which one would you expect to have the higher vapor pressure?
C. Describe a procedure that would make the two solutions have the same boiling point.
d. If you took $250 \mathrm{~mL}$ of the $\mathrm{AB}(a q)$ solution prepared above, would it have the same boiling point as the original solution? Be sure to explain your answer.
e. The container of $X Y(a q)$ is left out on the bench top for several days, which allows some of the water to evaporate from the solution. How would the melting point of this solution compare to the melting point of the original solution?

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02:35

Problem 26

Equal numbers of moles of two soluble, substances, substance $\mathrm{A}$ and substance $\mathrm{B}$, are placed into separate $1.0-\mathrm{L}$ samples of water.
a. The water samples are cooled. Sample A freezes at $-0.50^{\circ} \mathrm{C}$, and Sample $\mathrm{B}$ freezes at $-1.00^{\circ} \mathrm{C}$. Explain how the solutions can have different freezing points.
b. You pour $500 \mathrm{~mL}$ of the solution containing substance $\mathrm{B}$ into a different beaker. How would the freezing point of this $500-\mathrm{mL}$ portion of solution $\mathrm{B}$ compare to the freezing point of the $1.0-\mathrm{L}$ sample of solution $\mathrm{A}$ ?
c. Calculate the molality of the solutions of $\mathrm{A}$ and $\mathrm{B}$. Assume that $i=1$ for substance $\mathrm{A}$.
d. If you were to add an additional $1.0 \mathrm{~kg}$ of water to solution B, what would be the new freezing point of the solution? Try to write an answer to this question without using a mathematical formula.
e. What concentration (molality) of substances $\mathrm{A}$ and $\mathrm{B}$ would result in both solutions having a freezing point of $-0.25^{\circ} \mathrm{C}$ ?
f. Compare the boiling points, vapor pressure, and osmotic pressure of the original solutions of $\mathrm{A}$ and $\mathrm{B}$. Don't perform the calculations; just state which is the greater in each case.

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01:17

Problem 27

Even though the oxygen demands of trout and bass are different, they can exist in the same body of water. However, if the temperature of the water in the summer gets above about $23^{\circ} \mathrm{C}$, the trout begin to die, but not the bass. Why is this the case?

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02:09

Problem 28

You want to purchase a salt to melt snow and ice on your sidewalk. Which one of the following salts would best accomplish your task using the least amount: $\mathrm{KCl}, \mathrm{CaCl}_{2}, \mathrm{PbS}_{2}$, $\mathrm{MgSO}_{4}$, or $\mathrm{AgCl} ?$

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01:46

Problem 30

Small amounts of a nonvolatile, nonelectrolyte solute and a volatile solute are each dissolved in separate beakers containing $1 \mathrm{~kg}$ of water. If the number of moles of each solute is equal:
a. Which solution will have the higher vapor pressure?
b. Which solution will boil at a higher temperature?

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01:24

Problem 31

A Cottrell precipitator consists of a column containing electrodes that are connected to a high-voltage direct current (DC) source. The Cottrell precipitator is placed in smokestacks to remove smoke particles from the gas discharged from an industrial plant. Explain how you think this works.

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01:35

Problem 32

Consider the following dilute $\mathrm{NaCl}(a q)$ solutions.
a. Which one will boil at a higher temperature?
b. Which one will freeze at a lower temperature?
c. If the solutions were separated by a semipermeable membrane that allowed only water to pass, which solution would you expect to show an increase in the concentration of $\mathrm{NaCl} ?$

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01:32

Problem 33

A green leafy salad wilts if left too long in a salad dressing containing vinegar and salt. Explain what happens.

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01:41

Problem 34

People have proposed towing icebergs to arid parts of the earth as a way to deliver freshwater. Explain why icebergs do not contain salts although they are formed by the freezing of ocean water (i.e., saltwater).

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05:13

Problem 35

If $1-\mathrm{mol}$ samples of urea, a nonelectrolyte, sodium chloride, and calcium chloride are each dissolved in equal volumes of water in separate containers:
a. Which solution would have the highest boiling point?
b. Which solution would have the highest freezing point?

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02:05

Problem 36

Consider the following three beakers that contain water and a non-volatile solute. The solute is represented by the orange spheres.
a. Which solution would have the highest vapor pressure?
b. Which solution would have the lowest boiling point?
c. What could you do in the laboratory to make each solution have the same freezing point?

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01:10

Problem 37

Give an example of a liquid solution prepared by dissolving a gas in a liquid.

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01:14

Problem 38

Give an example of a solid solution prepared from two solids.

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01:23

Problem 39

Would boric acid, $\mathrm{B}(\mathrm{OH})_{3}$, be more soluble in ethanol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$, or in benzene, $\mathrm{C}_{6} \mathrm{H}_{6}$ ?

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01:24

Problem 40

Would naphthalene, $\mathrm{C}_{10} \mathrm{H}_{8}$, be more soluble in ethanol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$, or in benzene, $\mathrm{C}_{6} \mathrm{H}_{6}$ ?

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02:01

Problem 41

Arrange the following substances in order of increasing solubility in hexane, $\mathrm{C}_{6} \mathrm{H}_{14}: \mathrm{CH}_{2} \mathrm{OHCH}_{2} \mathrm{OH}, \mathrm{C}_{10} \mathrm{H}_{22}, \mathrm{H}_{2} \mathrm{O}$.

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01:30

Problem 42

Indicate which of the following is more soluble in ethanol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}:$ acetic acid, $\mathrm{CH}_{3} \mathrm{COOH}$, or stearic acid, $\mathrm{C}_{17} \mathrm{H}_{35} \mathrm{COOH}$.

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01:18

Problem 43

Which of the following ions would be expected to have the greater energy of hydration, $\mathrm{Mg}^{2+}$ or $\mathrm{Al}^{3+}$ ?

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01:09

Problem 44

Which of the following ions would be expected to have the greater energy of hydration, $\mathrm{F}^{-}$ or $\mathrm{Cl}^{-}$ ?

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01:52

Problem 45

Arrange the following alkaline-earth-metal iodates in order of increasing solubility in water; explain your reasoning:
$\mathrm{Ba}\left(\mathrm{IO}_{3}\right)_{2}, \mathrm{Ca}\left(\mathrm{IO}_{3}\right)_{2}, \mathrm{Sr}\left(\mathrm{IO}_{3}\right)_{2}, \mathrm{Mg}\left(\mathrm{IO}_{3}\right)_{2}$. Note that $\mathrm{IO}_{3}^{-}$ is a large anion.

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02:25

Problem 46

Explain the trends in solubility (grams per $100 \mathrm{~mL}$ of water) of the alkali-metal fluorides and permanganates.

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01:45

Problem 47

The solubility of carbon dioxide in water is $0.161 \mathrm{~g} \mathrm{CO}_{2}$ in $100 \mathrm{~mL}$ of water at $20^{\circ} \mathrm{C}$ and $1.00 \mathrm{~atm}$. A soft drink is carbonated with carbon dioxide gas at $5.50$ atm pressure. What is the solubility of carbon dioxide in water at this pressure?

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01:15

Problem 48

Nitrogen, $\mathrm{N}_{2}$, is soluble in blood and can cause intoxication at sufficient concentration. For this reason, the U.S. Navy advises divers using compressed air not to go below 125 feet. The total pressure at this depth is $4.79 \mathrm{~atm}$. If the solubility of nitrogen at $1.00$ atm is $1.75 \times 10^{-3} \mathrm{~g} / 100 \mathrm{~mL}$ of water, and the mole percent of nitrogen in air is $78.1$, what is the solubility of nitrogen in water from air at $4.79$ atm?

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01:50

Problem 49

How would you prepare $72.5 \mathrm{~g}$ of an aqueous solution that is $5.00 \%$ potassium iodide, KI, by mass?

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01:54

Problem 50

How would you prepare $455 \mathrm{~g}$ of an aqueous solution that is $6.50 \%$ sodium sulfate, $\mathrm{Na}_{2} \mathrm{SO}_{4}$, by mass?

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01:32

Problem 51

What mass of solution containing $5.00 \%$ potassium iodide, KI, by mass contains $258 \mathrm{mg}$ KI?

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01:35

Problem 52

What mass of solution containing $6.50 \%$ sodium sulfate, $\mathrm{Na}_{2} \mathrm{SO}_{4}$, by mass contains $1.50 \mathrm{~g} \mathrm{Na}_{2} \mathrm{SO}_{4} ?$

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01:36

Problem 53

Vanillin, $\mathrm{C}_{8} \mathrm{H}_{8} \mathrm{O}_{3}$, occurs naturally in vanilla extract and is used as a flavoring agent. A 39.1-mg sample of vanillin was dissolved in $168.5 \mathrm{mg}$ of diphenyl ether, $\left(\mathrm{C}_{6} \mathrm{H}_{5}\right)_{2} \mathrm{O} .$ What is the molality of vanillin in the solution?

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02:20

Problem 54

Lauryl alcohol, $\mathrm{C}_{12} \mathrm{H}_{25} \mathrm{OH}$, is prepared from coconut oil; it is used to make sodium lauryl sulfate, a synthetic detergent. What is the molality of lauryl alcohol in a solution of $17.1 \mathrm{~g}$ lauryl alcohol dissolved in $165 \mathrm{~g}$ ethanol, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$ ?

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01:30

Problem 55

Fructose, $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}$, is a sugar occurring in honey and fruits. The sweetest sugar, it is nearly twice as sweet as sucrose (cane or beet sugar). How much water should be added to $1.75 \mathrm{~g}$ of fructose to give a $0.125 \mathrm{~m}$ solution?

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01:25

Problem 56

Caffeine, $\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{~N}_{4} \mathrm{O}_{2}$, is a stimulant found in tea and coffee. A sample of the substance was dissolved in $45.0 \mathrm{~g}$ of chloroform, $\mathrm{CHCl}_{3}$, to give a $0.0946 \mathrm{~m}$ solution. How many grams of caffeine were in the sample?

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01:48

Problem 57

A $100.0-\mathrm{g}$ sample of a brand of rubbing alcohol contains $65.0 \mathrm{~g}$ of isopropyl alcohol, $\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH}$, and $35.0 \mathrm{~g}$ of water. What is the mole fraction of isopropyl alcohol in the solution? What is the mole fraction of water?

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02:57

Problem 58

An automobile antifreeze solution contains $2.50 \mathrm{~kg}$ of ethylene glycol, $\mathrm{CH}_{2} \mathrm{OHCH}_{2} \mathrm{OH}$, and $2.00 \mathrm{~kg}$ of water. Find the mole fraction of ethylene glycol in this solution. What is the mole fraction of water?

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01:19

Problem 59

A bleaching solution contains sodium hypochlorite, $\mathrm{NaClO}$, dissolved in water. The solution is $0.650 \mathrm{~m} \mathrm{NaClO}$. What is the mole fraction of sodium hypochlorite?

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02:20

Problem 60

An antiseptic solution contains hydrogen peroxide, $\mathrm{H}_{2} \mathrm{O}_{2}$, in water. The solution is $0.600 \mathrm{~m} \mathrm{H}_{2} \mathrm{O}_{2}$. What is the mole fraction of hydrogen peroxide?

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02:13

Problem 61

Concentrated hydrochloric acid contains $1.00 \mathrm{~mol} \mathrm{HCl}$ dissolved in $3.31 \mathrm{~mol} \mathrm{H}_{2} \mathrm{O}$. What is the mole fraction of $\mathrm{HCl}$ in concentrated hydrochloric acid? What is the molal concentration of HCl?

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02:26

Problem 62

Concentrated aqueous ammonia contains $1.00 \mathrm{~mol} \mathrm{NH}_{3}$ dissolved in $2.44 \mathrm{~mol} \mathrm{H}_{2} \mathrm{O} .$ What is the mole fraction of $\mathrm{NH}_{3}$ in concentrated aqueous ammonia? What is the molal concentration of $\mathrm{NH}_{3}$ ?

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02:35

Problem 63

Oxalic acid, $\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}$, occurs as the potassium or calcium salt in many plants, including rhubarb and spinach. An aqueous solution of oxalic acid is $0.580 \mathrm{~m} \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4} .$ The density of the solution is $1.022 \mathrm{~g} / \mathrm{mL}$. What is the molar concentration?

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01:59

Problem 64

Citric acid, $\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}$, occurs in plants. Lemons contain $5 \%$ to $8 \%$ citric acid by mass. The acid is added to beverages and candy. An aqueous solution is $0.688 m$ citric acid. The density is $1.049 \mathrm{~g} / \mathrm{mL}$. What is the molar concentration?

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03:18

Problem 65

A solution of vinegar is $0.763 M$ acetic acid, $\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}$. The density of the vinegar is $1.004 \mathrm{~g} / \mathrm{mL}$. What is the molal concentration of acetic acid?

Sima Sarker
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01:45

Problem 66

A beverage contains tartaric acid, $\mathrm{H}_{2} \mathrm{C}_{4} \mathrm{H}_{4} \mathrm{O}_{6}$, a substance obtained from grapes during wine making. If the beverage is $0.265 M$ tartaric acid, what is the molal concentration? The density of the solution is $1.016 \mathrm{~g} / \mathrm{mL}$.

Lottie Adams
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04:02

Problem 67

Calculate the vapor pressure at $35^{\circ} \mathrm{C}$ of a solution made by dissolving $20.2 \mathrm{~g}$ of sucrose, $\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$, in $70.1 \mathrm{~g}$ of water. The vapor pressure of pure water at $35^{\circ} \mathrm{C}$ is $42.2 \mathrm{mmHg}$. What is the vapor-pressure lowering of the solution? (Sucrose is nonvolatile.)

Sima Sarker
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04:22

Problem 68

What is the vapor pressure at $23^{\circ} \mathrm{C}$ of a solution of $1.20 \mathrm{~g}$ of naphthalene, $\mathrm{C}_{10} \mathrm{H}_{8}$, in $25.6 \mathrm{~g}$ of benzene, $\mathrm{C}_{6} \mathrm{H}_{6}$ ? The vapor pressure of pure benzene at $23^{\circ} \mathrm{C}$ is $86.0 \mathrm{mmHg} ;$ the vapor pressure of naphthalene can be neglected. Calculate the vaporpressure lowering of the solution.

Sima Sarker
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04:16

Problem 69

What is the boiling point of a solution of $0.150 \mathrm{~g}$ of glycerol, $\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}_{3}$, in $20.0 \mathrm{~g}$ of water? What is the freezing point?

Sima Sarker
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04:50

Problem 70

A solution was prepared by dissolving $0.834 \mathrm{~g}$ of sulfur, $\mathrm{S}_{8}$, in $100.0 \mathrm{~g}$ of acetic acid, $\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}$. Calculate the freezing point and boiling point of the solution.

Sima Sarker
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01:13

Problem 71

An aqueous solution of a molecular compound freezes at $-0.086^{\circ} \mathrm{C}$. What is the molality of the solution?

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03:22

Problem 72

Urea, $\left(\mathrm{NH}_{2}\right)_{2} \mathrm{CO}$, is dissolved in $100.0 \mathrm{~g}$ of water. The solution freezes at $-0.085^{\circ} \mathrm{C}$. How many grams of urea were dissolved to make this solution?

Sima Sarker
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02:21

Problem 73

A $0.0182-\mathrm{g}$ sample of an unknown substance was dissolved in $2.135 \mathrm{~g}$ of benzene. The molality of this solution, determined by freezing-point depression, was $0.0698 \mathrm{~m} .$ What is the molecular mass of the unknown substance?

Sima Sarker
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02:24

Problem 74

A solution contains $0.0653 \mathrm{~g}$ of a compound in $8.31 \mathrm{~g}$ of ethanol. The molality of the solution is $0.0368 \mathrm{~m} .$ Calculate the molecular mass of the compound.

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03:48

Problem 75

Safrole is contained in oil of sassafras and was once used to flavor root beer. A $2.39-\mathrm{mg}$ sample of safrole was dissolved in $103.0 \mathrm{mg}$ of diphenyl ether. The solution had a melting point of $25.70^{\circ} \mathrm{C}$. Calculate the molecular mass of safrole. The freezing point of pure diphenyl ether is $26.84^{\circ} \mathrm{C}$, and the freezing-pointdepression constant, $K_{f}$, is $8.00^{\circ} \mathrm{C} / m .$

Sima Sarker
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03:15

Problem 76

Butylated hydroxytoluene (BHT) is used as an antioxidant in processed foods. (It prevents fats and oils from becoming rancid.) A solution of $2.500 \mathrm{~g}$ of BHT in $100.0 \mathrm{~g}$ of benzene had a freezing point of $4.880^{\circ} \mathrm{C}$. What is the molecular mass of $\mathrm{BHT}$ ?

Sima Sarker
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03:39

Problem 77

Dextran is a polymeric carbohydrate produced by certain bacteria. It is used as a blood plasma substitute. An aqueous solution contains $0.582 \mathrm{~g}$ of dextran in $106 \mathrm{~mL}$ of solution at $21^{\circ} \mathrm{C}$. It has an osmotic pressure of $1.47 \mathrm{mmHg} .$ What is the average molecular mass of the dextran?

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03:47

Problem 78

Arginine vasopressin is a pituitary hormone. It helps regulate the amount of water in the blood by reducing the flow of urine from the kidneys. An aqueous solution containing $21.6 \mathrm{mg}$ of vasopressin in $100.0 \mathrm{~mL}$ of solution has an osmotic pressure at $25^{\circ} \mathrm{C}$ of $3.70 \mathrm{mmHg}$. What is the molecular mass of the hormone?

Sima Sarker
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01:40

Problem 79

What is the freezing point of $0.0075 \mathrm{~m}$ aqueous calcium chloride, $\mathrm{CaCl}_{2}$ ? Use the formula of the salt to obtain $i$.

Lottie Adams
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01:41

Problem 80

What is the freezing point of $0.0091 \mathrm{~m}$ aqueous sodium phosphate, $\mathrm{Na}_{3} \mathrm{PO}_{4}$ ? Use the formula of the salt to obtain $i$.

Sima Sarker
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02:07

Problem 81

A $0.0140-\mathrm{g}$ sample of an ionic compound with the formula $\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{Cl}_{3}$ was dissolved in water to give $25.0 \mathrm{~mL}$ of solution at $25^{\circ} \mathrm{C}$. The osmotic pressure was determined to be $119 \mathrm{mmHg}$. How many ions are obtained from each formula unit when the compound is dissolved in water?

Lottie Adams
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02:12

Problem 82

In a mountainous location, the boiling point of pure water is found to be $95^{\circ} \mathrm{C}$. How many grams of sodium chloride must be added to $1 \mathrm{~kg}$ of water to bring the boiling point back to $100^{\circ} \mathrm{C}$ ? Assume that $i=2$.

Lottie Adams
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01:30

Problem 83

Give the type of colloid (aerosol, foam, emulsion, sol, or gel) that each of the following represents.
a. rain cloud
b. milk of magnesia
c. soapsuds
d. silt in water

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01:41

Problem 84

Give the type of colloid (aerosol, foam, emulsion, sol, or
gel) that each of the following represents.
a. ocean spray
b. beaten egg white
c. dust cloud
d. salad dressing

Sima Sarker
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01:12

Problem 85

Arsenic(III) sulfide forms a sol with a negative charge. Which of the following ionic substances should be most effective in coagulating the sol?
a. $\mathrm{KCl}$
b. $\mathrm{MgCl}_{2}$
C. $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}$
d. $\mathrm{Na}_{3} \mathrm{PO}_{4}$

Sima Sarker
Sima Sarker
Numerade Educator
01:31

Problem 86

Aluminum hydroxide forms a positively charged sol. Which of the following ionic substances should be most effective in coagulating the sol?
a. $\mathrm{NaCl}$
b. $\mathrm{CaCl}_{2}$
C. $\mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}$
d. $\mathrm{K}_{3} \mathrm{PO}_{4}$

Sima Sarker
Sima Sarker
Numerade Educator
05:27

Problem 87

A gaseous mixture consists of $80.0$ mole percent $\mathrm{N}_{2}$ and $20.0$ mole percent $\mathrm{O}_{2}$ (the approximate composition of air). Suppose water is saturated with the gas mixture at $25^{\circ} \mathrm{C}$ and $1.00$ atm total pressure, and then the gas is expelled from the water by heating. What is the composition in mole fractions of the gas mixture that is expelled? The solubilities of $\mathrm{N}_{2}$ and $\mathrm{O}_{2}$ at $25^{\circ} \mathrm{C}$ and $1.00$ atm are $0.0175 \mathrm{~g} / \mathrm{L} \mathrm{H}_{2} \mathrm{O}$ and $0.0393 \mathrm{~g} / \mathrm{L} \mathrm{H}_{2} \mathrm{O}$, respectively.

Sima Sarker
Sima Sarker
Numerade Educator
05:23

Problem 88

A natural gas mixture consists of $90.0$ mole percent $\mathrm{CH}_{4}$ (methane) and $10.0$ mole percent $\mathrm{C}_{2} \mathrm{H}_{6}$ (ethane). Suppose water is saturated with the gas mixture at $20^{\circ} \mathrm{C}$ and $1.00$ atm total pres sure, and the gas is then expelled from the water by heating. What is the composition in mole fractions of the gas mixture that is expelled? The solubilities of $\mathrm{CH}_{4}$ and $\mathrm{C}_{2} \mathrm{H}_{6}$ at $20^{\circ} \mathrm{C}$ and $1.00$ atm are $0.023 \mathrm{~g} / \mathrm{L} \mathrm{H}_{2} \mathrm{O}$ and $0.059 \mathrm{~g} / \mathrm{L} \mathrm{H}_{2} \mathrm{O}$, respectively.

Sima Sarker
Sima Sarker
Numerade Educator
04:39

Problem 89

An aqueous solution is $8.50 \%$ ammonium chloride, $\mathrm{NH}_{4} \mathrm{Cl}$, by mass. The density of the solution is $1.024 \mathrm{~g} / \mathrm{mL}$. What are the molality, mole fraction, and molarity of $\mathrm{NH}_{4} \mathrm{Cl}$ in the solution?

Sima Sarker
Sima Sarker
Numerade Educator
03:59

Problem 90

An aqueous solution is $27.0 \%$ lithium chloride, $\mathrm{LiCl}$, by mass. The density of the solution is $1.127 \mathrm{~g} / \mathrm{mL}$. What are the molality, mole fraction, and molarity of $\mathrm{LiCl}$ in the solution?

Lottie Adams
Lottie Adams
Numerade Educator
04:26

Problem 91

A $55-\mathrm{g}$ sample of a gaseous fuel mixture contains $0.51$ mole fraction propane, $\mathrm{C}_{3} \mathrm{H}_{8}$; the remainder of the mixture is butane, $\mathrm{C}_{4} \mathrm{H}_{10}$. What are the masses of propane and butane in the sample?

Sima Sarker
Sima Sarker
Numerade Educator
07:05

Problem 92

The diving atmosphere used by the U.S. Navy in its undersea Sea-Lab experiments consisted of $0.036$ mole fraction $\mathrm{O}_{2}$ and $0.056$ mole fraction $\mathrm{N}_{2}$, with helium (He) making up the remainder. What are the masses of nitrogen, oxygen, and helium in a $8.32-\mathrm{g}$ sample of this atmosphere?

Henry He
Henry He
Numerade Educator
02:12

Problem 93

A liquid solution consists of $0.25$ mole fraction ethylene dibromide, $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Br}_{2}$, and $0.75 \mathrm{~mole}$ fraction propylene dibromide, $\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{Br}_{2} .$ Both ethylene dibromide and propylene dibromide are volatile liquids; their vapor pressures at $85^{\circ} \mathrm{C}$ are $173 \mathrm{mmHg}$ and $127 \mathrm{mmHg}$, respectively. Assume that each compound follows Raoult's law in the solution. Calculate the total vapor pressure of the solution.

Sima Sarker
Sima Sarker
Numerade Educator
01:20

Problem 94

What is the total vapor pressure at $20^{\circ} \mathrm{C}$ of a liquid solution containing $0.30$ mole fraction benzene, $\mathrm{C}_{6} \mathrm{H}_{6}$, and $0.70$ mole fraction toluene, $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{3}$ ? Assume that Raoult's law holds for each component of the solution. The vapor pressure of pure benzene at $20^{\circ} \mathrm{C}$ is $75 \mathrm{mmHg}$; that of toluene at $20^{\circ} \mathrm{C}$ is $22 \mathrm{mmHg}$.

Lottie Adams
Lottie Adams
Numerade Educator
14:48

Problem 95

A sample of potassium aluminum sulfate 12 -hydrate, $\mathrm{KAl}\left(\mathrm{SO}_{4}\right)_{2} \cdot 12 \mathrm{H}_{2} \mathrm{O}$, containing $118.6 \mathrm{mg}$ is dissolved in $1.000 \mathrm{~L}$
of solution. Calculate the following for the solution:
a. The molarity of $\mathrm{KAl}\left(\mathrm{SO}_{4}\right)_{2}$.
b. The molarity of $\mathrm{SO}_{4}^{2-}$.
C. The molality of $\mathrm{KAl}\left(\mathrm{SO}_{4}\right)_{2}$, assuming that the density of the solution is $1.00 \mathrm{~g} / \mathrm{mL}$.

S
Sue Stewart
Numerade Educator
08:13

Problem 96

A sample of aluminum sulfate 18 -hydrate, $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}$. $18 \mathrm{H}_{2} \mathrm{O}$, containing $159.3 \mathrm{mg}$ is dissolved in $1.000 \mathrm{~L}$ of solution. Calculate the following for the solution:
a. The molarity of $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}$ -
b. The molarity of $\mathrm{SO}_{4}^{2-}$.
c. The molality of $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}$, assuming that the density of the solution is $1.00 \mathrm{~g} / \mathrm{mL}$.

Henry He
Henry He
Numerade Educator
01:50

Problem 97

Urea, $\left(\mathrm{NH}_{2}\right)_{2} \mathrm{CO}$, has been used to melt ice from sidewalks, because the use of salt is harmful to plants. If the saturated aqueous solution contains $41 \%$ urea by mass, what is the freezing point? (The answer will be approximate, because the equation in the text applies accurately only to dilute solutions.)

Lottie Adams
Lottie Adams
Numerade Educator
03:02

Problem 98

Calcium chloride, $\mathrm{CaCl}_{2}$, has been used to melt ice from roadways. Given that the saturated solution is $32 \% \mathrm{CaCl}_{2}$ by mass, estimate the freezing point.

Sima Sarker
Sima Sarker
Numerade Educator
01:53

Problem 99

The osmotic pressure of blood at $37^{\circ} \mathrm{C}$ is $7.7 \mathrm{~atm} . \mathrm{A}$ solution that is given intravenously must have the same osmotic pressure as the blood. What should be the molarity of a glucose solution to give an osmotic pressure of $7.7 \mathrm{~atm}$ at $37^{\circ} \mathrm{C}$ ?

Lottie Adams
Lottie Adams
Numerade Educator
01:26

Problem 100

Maltose, $\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}$, is a sugar produced by malting (sprouting) grain. A solution of maltose at $25^{\circ} \mathrm{C}$ has an osmotic pressure of $5.50$ atm. What is the molar concentration of maltose?

Sima Sarker
Sima Sarker
Numerade Educator
01:43

Problem 101

Which aqueous solution has the lower freezing point, $0.10 \mathrm{~m} \mathrm{CaCl}_{2}$ or $0.10 \mathrm{~m}$ glucose?

Sima Sarker
Sima Sarker
Numerade Educator
02:01

Problem 102

Which aqueous solution has the lower boiling point, $0.10 \mathrm{~m} \mathrm{KCl}$ or $0.10 \mathrm{~m} \mathrm{CaCl}_{2} ?$

Sima Sarker
Sima Sarker
Numerade Educator
02:43

Problem 103

Commercially, sulfuric acid is obtained as a $98 \%$ solution. If this solution is $18 M$, what is its density? What is its molality?

Lottie Adams
Lottie Adams
Numerade Educator
01:51

Problem 104

Phosphoric acid is usually obtained as an $85 \%$ phosphoric acid solution. If it is $15 M$, what is the density of this solution? What is its molality?

Lottie Adams
Lottie Adams
Numerade Educator
02:46

Problem 105

A compound of manganese, carbon, and oxygen contains $28.17 \% \mathrm{Mn}$ and $30.80 \% \mathrm{C}$. When $0.125 \mathrm{~g}$ of this compound is dissolved in $5.38 \mathrm{~g}$ of cyclohexane, the solution freezes at $5.28^{\circ} \mathrm{C} .$ What is the molecular formula of this compound?

Lottie Adams
Lottie Adams
Numerade Educator
02:46

Problem 106

A compound of cobalt, carbon, and oxygen contains $28.10 \% \mathrm{C}$ and $34.47 \%$ Co. When $0.147 \mathrm{~g}$ of this compound is dissolved in $6.72 \mathrm{~g}$ of cyclohexane, the solution freezes at $5.23^{\circ} \mathrm{C}$. What is the molecular formula of this compound?

Lottie Adams
Lottie Adams
Numerade Educator
02:19

Problem 107

The carbohydrate digitoxose contains $48.64 \%$ carbon and $8.16 \%$ hydrogen. The addition of $18.0 \mathrm{~g}$ of this compound to
100. g of water gives a solution that has a freezing point of $-2.2^{\circ} \mathrm{C}$
a. What is the molecular formula of the compound?
b. What is the molar mass of this compound to the nearest tenth of a gram?

Lottie Adams
Lottie Adams
Numerade Educator
13:53

Problem 108

Analysis of a compound gave $39.50 \%$ C, $2.21 \% \mathrm{H}$, and $58.30 \%$ Cl. When $0.855 \mathrm{~g}$ of this solid was dissolved in $7.50 \mathrm{~g}$ of naphthalene, the solution had a freezing point of $78.0^{\circ} \mathrm{C}$. The pure solvent freezes at $80.0^{\circ} \mathrm{C} ;$ its molal freezing point constant is $6.8^{\circ} \mathrm{C} / \mathrm{m}$
a. What is the molecular formula of the compound?
b. What is its molecular mass to the nearest $0.1 \mathrm{~g}$ ?

S
Sue Stewart
Numerade Educator
03:44

Problem 109

Fish blood has an osmotic pressure equal to that of seawater. If seawater freezes at $-2.3^{\circ} \mathrm{C}$, what is the osmotic pressure of the blood at $25^{\circ} \mathrm{C} ?$ To solve this problem, what assumptions must be made?

Sima Sarker
Sima Sarker
Numerade Educator
03:50

Problem 110

A salt solution has an osmotic pressure of 17 atmospheres at $22^{\circ} \mathrm{C}$. What is the freezing point of this solution? What assumptions must be made to solve this problem?

Sima Sarker
Sima Sarker
Numerade Educator
02:14

Problem 111

What is the difference between normal hemoglobin and the hemoglobin associated with sickle-cell anemia? How does this affect the solubility of the hemoglobin?

Lottie Adams
Lottie Adams
Numerade Educator
02:44

Problem 112

What tends to happen to the hemoglobin in a blood cell of a person who has sickle-cell anemia? How does this affect the shape and oxygen-carrying capacity of the cell?

Angelique Amado-Gonzales
Angelique Amado-Gonzales
Numerade Educator
01:59

Problem 113

How are phospholipids similar in structure to a soap molecule? What structural difference accounts for the fact that phospholipids form lipid bilayers rather than the micelles that soaps form?

Lottie Adams
Lottie Adams
Numerade Educator
01:47

Problem 114

How have chemists used these phospholipids to form "the world's smallest test tubes"? Describe how these phospholipid vesicles might be used.

Lottie Adams
Lottie Adams
Numerade Educator
02:34

Problem 115

When $79.3 \mathrm{~g}$ of a particular compound is dissolved in $0.878 \mathrm{~kg}$ of water at 1 atm pressure, the solution freezes at $-1.34^{\circ} \mathrm{C}$. If the compound does not undergo ionization in solution and is nonvolatile, determine the molecular mass of the compound.

Sima Sarker
Sima Sarker
Numerade Educator
02:55

Problem 116

What is the boiling point of a solution made by adding $6.69 \mathrm{~g}$ of magnesium chloride to $243.3 \mathrm{~g}$ of water? Use the formula of the salt to obtain $\vec{i}$

Sima Sarker
Sima Sarker
Numerade Educator
02:26

Problem 117

At $15^{\circ} \mathrm{C}$ and a partial pressure of $2.14$ atm, the solubility of an unknown gas in a liquid is $15.6 \mathrm{~g} / \mathrm{L}$. What is the solubility of the gas in the liquid when the partial pressure of the gas is

Sima Sarker
Sima Sarker
Numerade Educator
02:17

Problem 118

Methanol, $\mathrm{CH}_{3} \mathrm{OH}$, is a compound that is used in car windshield washer fluid to lower the freezing point of the solution. If an aqueous solution of windshield washer fluid has a mole fraction of methanol of $0.520$, what is the mass percentage of water in this solution?

Sima Sarker
Sima Sarker
Numerade Educator
01:52

Problem 119

How many grams of potassium chloride must be added to $372 \mathrm{~g}$ of water in order to prepare a $0.110 \mathrm{~m}$ potassium chloride solution?

Lottie Adams
Lottie Adams
Numerade Educator
01:53

Problem 120

Although somewhat toxic, barium chloride has been used as a cardiac stimulant. Calculate the number of moles of barium chloride in $427 \mathrm{~g}$ of a $3.17 \%$ by mass barium chloride solution?

Sima Sarker
Sima Sarker
Numerade Educator
01:40

Problem 121

Ethanol, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$, is known as grain alcohol and is the alcohol found in alcoholic beverages. Calculate the mole fraction of ethanol in a solution that contains $4.76 \mathrm{~g}$ of ethanol dissolved in $50.0 \mathrm{~g}$ of water.

Lottie Adams
Lottie Adams
Numerade Educator
03:12

Problem 122

A starch has a molar mass of $3.20 \times 10^{04} \mathrm{~g} / \mathrm{mol}$. If $0.759 \mathrm{~g}$ of this starch is dissolved in $112 \mathrm{~mL}$ of solution, what is the osmotic pressure, in torr, at $25.00^{\circ} \mathrm{C} ?$

Sima Sarker
Sima Sarker
Numerade Educator
02:35

Problem 123

An aqueous solution is $0.797 M$ magnesium chloride. Given that the density of the solution is $1.108 \mathrm{~g} / \mathrm{mL}$, what is the molality of magnesium chloride in this solution?

Lottie Adams
Lottie Adams
Numerade Educator
02:43

Problem 124

A $\mathrm{CaCl}_{2}$ solution at $25^{\circ} \mathrm{C}$ has an osmotic pressure of $16 \mathrm{~atm}$ and a density of $1.108 \mathrm{~g} / \mathrm{mL}$. What is the freezing point of this solution?

Lottie Adams
Lottie Adams
Numerade Educator
12:40

Problem 125

An experimenter makes up a solution of $0.375 \mathrm{~mol}$ $\mathrm{Na}_{2} \mathrm{CO}_{3}, 0.125 \mathrm{~mol} \mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}$, and $0.200 \mathrm{~mol} \mathrm{AgNO}_{3}$ in $2.000 \mathrm{~L}$
of water solution. Note any precipitations that occur, writing a balanced equation for each. Then, calculate the molarities of each ion in the solution.

Henry He
Henry He
Numerade Educator
11:49

Problem 126

An experimenter makes up a solution of $0.310 \mathrm{~mol}$ $\mathrm{Na}_{3} \mathrm{PO}_{4}, 0.100 \mathrm{~mol} \mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}$, and $0.150 \mathrm{~mol} \mathrm{AgNO}_{3}$ in $4.000 \mathrm{~L}$
of water solution. Note any precipitations that occur, writing $\mathrm{a}$ balanced equation for each. Then, calculate the molarities of each ion in the solution.

Henry He
Henry He
Numerade Educator
02:59

Problem 127

The lattice enthalpy of sodium chloride, $\Delta H^{\circ}$ for
$$\mathrm{NaCl}(s) \longrightarrow \mathrm{Na}^{+}(g)+\mathrm{Cl}^{-}(g)$$
is $787 \mathrm{~kJ} / \mathrm{mol} ;$ the heat of solution in making up $1 \mathrm{M} \mathrm{NaCl}(a q)$ is $+4.0 \mathrm{~kJ} / \mathrm{mol}$. From these data, obtain the sum of the heats of hydration of $\mathrm{Na}^{+}$ and $\mathrm{Cl}^{-}$. That is, obtain the sum of $\Delta H^{\text {values for }}$
$$\begin{aligned}&\mathrm{Na}^{+}(g) \longrightarrow \mathrm{Na}^{+}(a q) \\
&\mathrm{Cl}^{+}(g) \longrightarrow \mathrm{Cl}^{-}(a q)\end{aligned}$$
If the heat of hydration of $\mathrm{Cl}^{-}$ is $-338 \mathrm{~kJ} / \mathrm{mol}$, what is the heat of hydration of $\mathrm{Na}^{+}$ ?

Lottie Adams
Lottie Adams
Numerade Educator
02:16

Problem 128

The lattice enthalpy of potassium chloride is 717 $\mathrm{kJ} / \mathrm{mol} ;$ the heat of solution in making up $1 \mathrm{M} \mathrm{KCl}(a q)$ is $+18.0$ $\mathrm{kJ} / \mathrm{mol}$. Using the value for the heat of hydration of $\mathrm{Cl}^{-}$ given in Problem $12.125$, obtain the heat of hydration of $K^{+}$. Compare this with the value you obtained for $\mathrm{Na}^{+}$ in Problem $12.127 .$ Explain the relative values of $\mathrm{Na}^{+}$ and $\mathrm{K}^{+}$.

Lottie Adams
Lottie Adams
Numerade Educator
01:33

Problem 129

Ten grams of the hypothetical ionic compounds $\mathrm{XZ}$ and YZ are each placed in a separate $2.0-\mathrm{L}$ beaker of water. $\mathrm{XZ}$ completely dissolves, whereas YZ is insoluble. The energy of hydration of the $\mathrm{Y}^{+}$ ion is greater than the $\mathrm{X}^{+}$ ion. Explain this difference in solubility.

Lottie Adams
Lottie Adams
Numerade Educator
03:37

Problem 129

A solution is made up by dissolving $15.0 \mathrm{~g} \mathrm{MgSO}_{4}$ " $7 \mathrm{H}_{2} \mathrm{O}$ in $100.0 \mathrm{~g}$ of water. What is the molality of $\mathrm{MgSO}_{4}$ in this solution?

Sima Sarker
Sima Sarker
Numerade Educator
03:20

Problem 130

A solution is made up by dissolving $15.0 \mathrm{~g} \mathrm{Na}_{2} \mathrm{CO}_{3}$ " $10 \mathrm{H}_{2} \mathrm{O}$ in $100.0 \mathrm{~g}$ of water. What is the molality of $\mathrm{Na}_{2} \mathrm{CO}_{3}$ in this solution?

Sima Sarker
Sima Sarker
Numerade Educator
01:39

Problem 131

An aqueous solution is $15.0 \%$ by mass of copper(II) sulfate pentahydrate, $\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O} .$ What is the molarity of $\mathrm{CuSO}_{4}$ in this solution at $20^{\circ} \mathrm{C}$ ? The density of this solution at $20^{\circ} \mathrm{C}$ is $1.167 \mathrm{~g} / \mathrm{mL}$

Lottie Adams
Lottie Adams
Numerade Educator
01:37

Problem 132

An aqueous solution is $20.0 \%$ by mass of sodium thiosulfate pentahydrate, $\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3} \cdot 5 \mathrm{H}_{2} \mathrm{O} .$ What is the molarity of $\mathrm{Na}_{2} \mathrm{~S}_{2} \mathrm{O}_{3}$ in this solution at $20^{\circ} \mathrm{C} ?$ The density of this solution at $20^{\circ} \mathrm{C}$ is $1.174 \mathrm{~g} / \mathrm{mL}$

Lottie Adams
Lottie Adams
Numerade Educator
02:13

Problem 133

The freezing point of $0.0830 m$ aqueous acetic acid is $-0.159^{\circ} \mathrm{C}$. Acetic acid, $\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}$, is partially dissociated according to the equation
$$\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}(a q) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}^{-}(a q)$$
Calculate the percentage of $\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}$ molecules that are dissociated, assuming the equation for the freezing-point depression holds for the total concentration of molecules and ions in the solution.

Lottie Adams
Lottie Adams
Numerade Educator
01:23

Problem 134

The freezing point of $0.109 \mathrm{~m}$ aqueous formic acid is $-0.210^{\circ} \mathrm{C}$. Formic acid, $\mathrm{HCHO}_{2}$, is partially dissociated according to the equation
$$\mathrm{HCHO}_{2}(a q) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{CHO}_{2}^{-}(a q)$$
Calculate the percentage of $\mathrm{HCHO}_{2}$ molecules that are dissociated, assuming the equation for the freezing-point depression holds for the total concentration of molecules and ions in the solution.

Lottie Adams
Lottie Adams
Numerade Educator
14:40

Problem 135

A compound of carbon, hydrogen, and oxygen was burned in oxygen, and $1.000 \mathrm{~g}$ of the compound produced $1.434 \mathrm{~g} \mathrm{CO}_{2}$ and $0.783 \mathrm{~g} \mathrm{H}_{2} \mathrm{O} .$ In another experiment, $0.1107 \mathrm{~g}$ of the compound was dissolved in $25.0 \mathrm{~g}$ of water. This solution had a freezing point of $-0.0894^{\circ} \mathrm{C}$. What is the molecular formula of the compound?

Henry He
Henry He
Numerade Educator
08:12

Problem 136

A compound of carbon, hydrogen, and oxygen was burned in oxygen, and $1.000 \mathrm{~g}$ of the compound produced $1.418 \mathrm{~g} \mathrm{CO}_{2}$ and $0.871 \mathrm{~g} \mathrm{H}_{2} \mathrm{O} .$ In another experiment, $0.1103 \mathrm{~g}$ of the compound was dissolved in $45.0 \mathrm{~g}$ of water. This solution had a freezing point of $-0.0734^{\circ} \mathrm{C}$. What is the molecular formula of the compound?

Sima Sarker
Sima Sarker
Numerade Educator