Chemistry: The Central Science in SI Units, Global Edition

Theodore L. Brown, Matthew W. Stoltzfus, Michael W. Lufaso

Chapter 13

Properties of Solutions - all with Video Answers

Educators

Chapter Questions

Problem 1

Rank the contents of the following containers in order of increasing entropy: [Section 13.1]
(a)
(b)
(c)

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 2

This figure shows the interaction of a cation with surrounding water molecules.(a) Which atom of water is associated with the cation? Explain.
(b) Which of the following explanations accounts for the fact that the ion-solvent interaction is greater for $\mathrm{Li}^{+}$ than for $\mathrm{K}^{+}$ ?
a. $\mathrm{Li}^{+}$ is of lower mass than $\mathrm{K}^{+}$.
b. The ionization energy of Li is higher than that for K.
c. $\mathrm{Li}^{+}$ has a smaller ionic radius than $\mathrm{K}^{+}$.
d. Li has a lower density than K.
e. Li reacts with water more slowly than K. [Section 13.1]

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 3

Consider two ionic solids, both composed of singly charged ions, that have different lattice energies. (a) Will the solids have the same solubility in water? (b) If not, which solid will be more soluble in water, the one with the larger lattice energy or the one with the smaller lattice energy? Assume that solute-solvent interactions are the same for both solids. [Section 13.1]

Joanna Josey

Numerade Educator

Problem 4

Which two statements about gas mixtures are true? [Section 13.1]
(a) Gases always mix with other gases because the gas particles are too far apart to feel significant intermolecular attractions or repulsions.
(b) Just like water and oil don't mix in the liquid phase, two gases can be immiscible and not mix in the gas phase.
(c) If you cool a gaseous mixture, you will liquefy all the gases at the same temperature.
(d) Gases mix in all proportions in part because the entropy of the system increases upon doing so.

Snow Popis

Numerade Educator

Problem 5

Which of the following is the best representation of a saturated solution? Explain your reasoning. [Section 13.2]

Nadia Lara

Numerade Educator

Problem 6

If you compare the solubilities of the noble gases in water, you find that solubility increases from smallest atomic weight to largest, $\mathrm{Ar}<\mathrm{Kr}<\mathrm{Xe}$. Which of the following statements is the best explanation? [Section 13.3]
(a) The heavier the gas, the more it sinks to the bottom of the water and leaves room for more gas molecules at the top of the water.
(b) The heavier the gas, the more dispersion forces it has, and therefore the more attractive interactions it has with water molecules.
(c) The heavier the gas, the more likely it is to hydrogenbond with water.
(d) The heavier the gas, the more likely it is to make a saturated solution in water.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 7

The structures of vitamins $\mathrm{E}$ and $\mathrm{B}_{6}$ are shown below. Predict which is more water soluble and which is more fat soluble. [Section 13.3]

Nadia Lara

Numerade Educator

Problem 8

You take a sample of water that is at room temperature and in contact with air and put it under a vacuum. Right away, you see bubbles leave the water, but after a little while, the bubbles stop. As you keep applying the vacuum, more bubbles appear. A friend tells you that the first bubbles were water vapor, and the low pressure had reduced the boiling point of water, causing the water to boil. Another friend tells you that the first bubbles were gas molecules from the air (oxygen, nitrogen, and so forth) that were dissolved in the water. Which friend is mostly likely to be correct? What, then, is responsible for the second batch of bubbles? [Section 13.4]

Snow Popis

Numerade Educator

Problem 9

The figure shows two identical volumetric flasks containing the same solution at two temperatures.
(a) Does the molarity of the solution change with the change in temperature?
(b) Does the molality of the solution change with the change in temperature? [Section 13.4$]$

Nadia Lara

Numerade Educator

Problem 10

This portion of a phase diagram shows the vapor-pressure curves of a volatile solvent and of a solution of that solvent containing a nonvolatile solute.
(a) Which line represents the solution?
(b) What are the normal boiling points of the solvent and the solution? [Section 13.5]

Snow Popis

Numerade Educator

Problem 11

Suppose you had a balloon made of some highly flexible semipermeable membrane. The balloon is filled completely with a $0.2 \mathrm{M}$ solution of some solute and is submerged in a 0.1 $M$ solution of the same solute:
Initially, the volume of solution in the balloon is $0.25 \mathrm{~L}$. Assuming the volume outside the semipermeable membrane is large, as the illustration shows, what would you expect for the solution volume inside the balloon once the system has come to equilibrium through osmosis? [Section 13.5]

Joanna Josey

Numerade Educator

Problem 12

Which diagram best represents a liquid-liquid emulsion such as milk? The colored balls represent different liquid molecules. [Section 13.6]
a.
b.
c.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 13

Indicate whether each statement is true or false:
(a) A solute will dissolve in a solvent if solute-solute interactions are stronger than solute-solvent interactions.
(b) In making a solution, the enthalpy of mixing is always a positive number.
(c) An increase in entropy favors mixing.

Joanna Josey

Numerade Educator

Problem 14

Indicate whether each statement is true or false:
$($ a) $\mathrm{NaCl}$ dissolves in water but not in benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ because benzene is denser than water.
(b) NaCl dissolves in water but not in benzene because water has a large dipole moment and benzene has zero dipole moment.
(c) NaCl dissolves in water but not in benzene because the water-ion interactions are stronger than benzene-ion interactions.

Snow Popis

Numerade Educator

Problem 15

Indicate the type of solute-solvent interaction (Section 11.2) that should be most important in each of the following solutions: $(\mathbf{a}) \mathrm{CCl}_{4}$ in benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right),(\mathbf{b})$ methanol $\left(\mathrm{CH}_{3} \mathrm{OH}\right)$ in water, $(\mathbf{c}) \mathrm{KBr}$ in water, (d) HCl in acetonitrile $\left(\mathrm{CH}_{3} \mathrm{CN}\right).$

Nadia Lara

Numerade Educator

Problem 16

Indicate the principal type of solute-solvent interaction in each of the following solutions and rank the solutions from weakest to strongest solute-solvent interaction: (a) KCl in water, (b) $\mathrm{CH}_{2} \mathrm{Cl}_{2}$ in benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right),(\mathbf{c})$ methanol $\left(\mathrm{CH}_{3} \mathrm{OH}\right)$ in water.

Snow Popis

Numerade Educator

Problem 17

An ionic compound has a very negative $\Delta H_{\text {soln }}$ in water.
(a) Would you expect it to be very soluble or nearly insoluble in water?
(b) Which term would you expect to be the largest negative number: $\Delta H_{\text {solvent }}, \Delta H_{\text {solute }}$, or $\Delta H_{\text {mix }} ?$

Joanna Josey

Numerade Educator

Problem 18

When ammonium chloride dissolves in water, the solution becomes colder.
(a) Is the solution process exothermic or endothermic? (b) Why does the solution form?

Snow Popis

Numerade Educator

Problem 19

(a) In Equation 13.1, which of the enthalpy terms for dissolving an ionic solid would correspond to the lattice energy?
(b) Which energy term in this equation is always exothermic?

Joanna Josey

Numerade Educator

Problem 20

For the dissolution of $\mathrm{NaCl}$ in water, $\Delta H_{\mathrm{soln}}=+3 \mathrm{~kJ} / \mathrm{mol}$. Which term would you expect to be the largest negative number: $\Delta H_{\text {solute, }} \Delta H_{\text {solvent }}$, or $\Delta H_{\text {miv }}{ }^{2}.$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 21

Two nonpolar organic liquids, benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ and toluene $\left(\mathrm{C}_{7} \mathrm{H}_{8}\right),$ are mixed. (a) Do you expect $\Delta H_{\text {soln }}$ to be a large positive number, a large negative number, or close to zero? Explain. (b) Benzene and toluene are miscible with each other in all proportions. In making a solution of them, is the entropy of the system increased, decreased, or close to zero, compared to the separate pure liquids?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 22

$\mathrm{KBr}$ is relatively soluble in water, yet its enthalpy of solution is $+19.8 \mathrm{~kJ} / \mathrm{mol}$. Which of the following statements provides the best explanation for this behavior?
(a) Potassium salts are always soluble in water.
(b) The entropy of mixing must be unfavorable.
(c) The enthalpy of mixing must be small compared to the enthalpies for breaking up water-water interactions and K-Br ionic interactions.
(d) $\mathrm{KBr}$ has a high molar mass compared to other salts like $\mathrm{NaCl}$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 23

The solubility of alum, $\mathrm{KAl}\left(\mathrm{SO}_{4}\right)_{2} \cdot 12 \mathrm{H}_{2} \mathrm{O},$ in water at is $44 \mathrm{~g}$
per $100 \mathrm{~g}$ of water at $50^{\circ} \mathrm{C}$. A solution of alum in water at $80^{\circ} \mathrm{C}$ is formed by dissolving $130 \mathrm{~g}$ in $100 \mathrm{~g}$ of water. When this solution is slowly cooled to $50^{\circ} \mathrm{C},$ no precipitate forms. (a) Is the solution that has cooled down to $50^{\circ} \mathrm{C}$ unsaturated, saturated, or supersaturated? (b) You take a metal spatula and scratch the side of the glass vessel that contains this cooled solution, and crystals start to appear. What has just happened? (c) At equilibrium, what mass of crystals do you expect to form?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 24

The solubility of copper (II) sulfate pentahydrate $\left(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\right)$ in water at $30^{\circ} \mathrm{C}$ is $50 \mathrm{~g}$ per $100 \mathrm{~mL}$ of water. (a) Is a $1.30 \mathrm{M}$ solution of $\mathrm{CuSO}_{4} \cdot 12 \mathrm{H}_{2} \mathrm{O}$ in water at $30^{\circ} \mathrm{C}$ saturated, supersaturated, or unsaturated? (b) Given a solution of $\mathrm{CuSO}_{4} \cdot 12 \mathrm{H}_{2} \mathrm{O}$ of unknown concentration, what experiment could you perform to determine whether the new solution is saturated, supersaturated, or unsaturated?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 25

By referring to Figure $13.15,$ determine whether the addition of $50.0 \mathrm{~g}$ of each of the following ionic solids to $100 \mathrm{~g}$ of water at $20^{\circ} \mathrm{C}$ will lead to a saturated solution: $(\mathbf{a}) \mathrm{NaCl},$ (b) $\mathrm{CaCl}_{2}$ (c) $\mathrm{KNO}_{3}$, (d) $\mathrm{NaNO}_{3}.$

Sima Sarker

Numerade Educator

Problem 26

By referring to Figure $13.15,$ determine the mass of each of the following salts required to form a saturated solution in $250 \mathrm{~g}$ of water at $20^{\circ} \mathrm{C}$ :
(a) $\mathrm{NaCl},$
(b) $\mathrm{CaCl}_{2},$
(c) $\mathrm{KNO}_{3}.$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 27

Consider water and glycerol, $\mathrm{CH}_{2}(\mathrm{OH}) \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{2} \mathrm{OH}$.
(a) Would you expect them to be miscible in all proportions?
(b) List the intermolecular attractions that occur between a water molecule and a glycerol molecule.

Nadia Lara

Numerade Educator

Problem 28

Oil and water are immiscible. Which is the most likely reason?
(a) Oil molecules are denser than water.
(b) Oil molecules are composed mostly of carbon and hydrogen.
(c) Oil molecules have higher molar masses than water.
(d) Oil molecules have higher vapor pressures than water.
(e) Oil molecules have higher boiling points than water.

Snow Popis

Numerade Educator

Problem 29

Common laboratory solvents include acetone $\left(\mathrm{CH}_{3} \mathrm{COCH}_{3}\right)$, methanol $\left(\mathrm{CH}_{3} \mathrm{OH}\right)$, toluene $\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{3}\right),$ and water. Which of these is the best solvent for nonpolar solutes?

Nadia Lara

Numerade Educator

Problem 30

Would you expect alanine (an amino acid) to be more soluble in water or in hexane?

Snow Popis

Numerade Educator

Problem 31

(a) Would you expect stearic acid, $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{16} \mathrm{COOH},$ to be more soluble in water or in carbon tetrachloride?
(b) Which would you expect to be more soluble in water, cyclohexane or dioxane?

Nadia Lara

Numerade Educator

Problem 32

Ibuprofen, widely used as a pain reliever, has a limited solubility in water, less than $1 \mathrm{mg} / \mathrm{mL}$. Which part of the molecule's structure (gray, white, red) contributes to its water solubility? Which part of the molecule (gray, white, red) contributes to its water insolubility?

Snow Popis

Numerade Educator

Problem 33

Which of the following in each pair is likely to be more soluble in hexane, $\mathrm{C}_{6} \mathrm{H}_{14}:$ (a) $\mathrm{CCl}_{4}$ or $\mathrm{CaCl}_{2}$, (b) benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ or glycerol, $\mathrm{CH}_{2}(\mathrm{OH}) \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_{2} \mathrm{OH},$ (c) octanoic acid, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COOH},$ or acetic acid,
$\mathrm{CH}_{3} \mathrm{COOH}$ ? Explain your answer in each case.

Nadia Lara

Numerade Educator

Problem 34

Which of the following in each pair is likely to be more soluble in water: (a) cyclohexane $\left(\mathrm{C}_{6} \mathrm{H}_{12}\right)$ or glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$, (b) propionic acid $\left(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COOH}\right)$ or sodium propionate $\left(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{COONa}\right),(\mathbf{c}) \mathrm{HCl}$ or ethyl chloride $\left(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl}\right) ?$
Explain in each case.

Shubham Kumar

Numerade Educator

Problem 35

Indicate whether each statement is true or false:
(a) The higher the temperature, the more soluble most gases are in water.
(b) The higher the temperature, the more soluble most ionic solids are in water.
(c) As you cool a saturated solution from high temperature to low temperature, solids start to crystallize out of solution if you achieve a supersaturated solution.
(d) If you take a saturated solution and raise its temperature, you can (usually) add more solute and make the solution even more concentrated.

Nadia Lara

Numerade Educator

Problem 36

Indicate whether each statement is true or false:
(a) If you compare the solubility of a gas in water at two different temperatures, you find the gas is more soluble at the lower temperature.
(b) The solubility of most ionic solids in water decreases as the temperature of the solution increases.
(c) The solubility of most gases in water decreases as the temperature increases because water is breaking its hydrogen bonding to the gas molecules as the temperature is raised.
(d) Some ionic solids become less soluble in water as the temperature is raised.

Snow Popis

Numerade Educator

Problem 37

The Henry's law constant for hydrogen gas $\left(\mathrm{H}_{2}\right)$ in water at $25^{\circ} \mathrm{C}$ is $7.7 \times 10^{-6} \mathrm{M} / \mathrm{kPa}$ and the constant for argon (Ar) at $25^{\circ} \mathrm{C}$ is $1.4 \times 10^{-5} \mathrm{M} / \mathrm{kPa}$. If the two gases are each present at $253 \mathrm{kPa}$ pressure, calculate the solubility of each gas.

Sima Sarker

Numerade Educator

Problem 38

The partial pressure of $\mathrm{N}_{2}$ in air at sea level is $79 \mathrm{kPa}$. Using the data in Table 13.1 , together with Henry's law, calculate the molar concentration of $\mathrm{N}_{2}$ in the surface water of a mountain lake saturated with air at $20^{\circ} \mathrm{C}$ and an atmospheric pressure of $86.6 \mathrm{kPa}$.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 39

(a) Calculate the mass percentage of $\mathrm{NaNO}_{3}$ in a solution containing $13.6 \mathrm{~g}$ of $\mathrm{NaNO}_{3}$ in $834 \mathrm{~g}$ of water. (b) An alloy contains $2.86 \mathrm{~g}$ of chromium per $100 \mathrm{~kg}$ of alloy. What is the concentration of chromium in ppm?

Sima Sarker

Numerade Educator

Problem 40

(a) What is the mass percentage of iodine in a solution containing $0.035 \mathrm{~mol} \mathrm{I}_{2}$ in $125 \mathrm{~g}$ of $\mathrm{CCl}_{4} ?$ (b) Seawater contains $0.0079 \mathrm{~g}$ of $\mathrm{Sr}^{2+}$ per kilogram of water. What is the concentration of $\mathrm{Sr}^{2+}$ in ppm?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 41

A solution is made containing $50.0 \mathrm{~g}$ of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ in $1000 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{O} .$ Calculate $(\mathbf{a})$ the mole fraction of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH},$ (b) the mass percent of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$, (c) the molality of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$.

Sima Sarker

Numerade Educator

Problem 42

A solution is made containing $20.8 \mathrm{~g}$ of phenol $\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}\right)$ in $425 \mathrm{~g}$ of ethanol $\left(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\right)$. Calculate
(a) the mole fraction of phenol, (b) the mass percent of phenol, $(\mathbf{c})$ the molality of phenol.

Snow Popis

Numerade Educator

Problem 43

Calculate the molarity of the following aqueous solutions:
(a) $0.640 \mathrm{~g}$ of $\mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}$ in $500.0 \mathrm{~mL}$ of solution,
(b) $50.0 \mathrm{~g}$
of $\mathrm{LiClO}_{4} \cdot 3 \mathrm{H}_{2} \mathrm{O}$ in $250 \mathrm{~mL}$ of solution,
(c) $125 \mathrm{~mL}$ of $3.00 \mathrm{M}$
$\mathrm{HNO}_{3}$ diluted to $1.00 \mathrm{~L}$

Sima Sarker

Numerade Educator

Problem 44

What is the molarity of each of the following solutions:
(a) $15.0 \mathrm{~g}$ of $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}$ in $0.250 \mathrm{~mL}$ solution,
(b) $5.25 \mathrm{~g}$ of
$\mathrm{Mn}\left(\mathrm{NO}_{3}\right)_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}$ in $175 \mathrm{~mL}$ of solution,
(c) $35.0 \mathrm{~mL}$ of
$9.00 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$ diluted to $0.500 \mathrm{~L} ?$

Snow Popis

Numerade Educator

Problem 45

Calculate the molality of each of the following solutions:
(a) $10.0 \mathrm{~g}$ of benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ dissolved in $50.0 \mathrm{~g}$ of carbon tetrachloride $\left(\mathrm{CCl}_{4}\right),(\mathbf{b}) 5.00 \mathrm{~g}$ of $\mathrm{NaCl}$ dissolved in $0.100 \mathrm{~L}$
of water.

Sima Sarker

Numerade Educator

Problem 46

(a) What is the molality of a solution formed by dissolving 1.12 mol of KCl in 16.0 mol of water?
(b) How many grams of sulfur $\left(\mathrm{S}_{8}\right)$ must be dissolved in $100.0 \mathrm{~g}$ of naphthalene $\left(\mathrm{C}_{10} \mathrm{H}_{8}\right)$ to make a $0.12 \mathrm{~m}$ solution?

Snow Popis

Numerade Educator

Problem 47

A sulfuric acid solution containing $697.6 \mathrm{~g}$ of $\mathrm{H}_{2} \mathrm{SO}_{4}$ per liter of solution has a density of $1.395 \mathrm{~g} / \mathrm{cm}^{3} .$ Calculate
(a) the mass percentage,
$(\mathbf{b})$ the mole fraction,
(c) the molality, $(\mathbf{d})$ the molarity of $\mathrm{H}_{2} \mathrm{SO}_{4}$ in this solution.

Sima Sarker

Numerade Educator

Problem 48

Ascorbic acid (vitamin C, $\left.\mathrm{C}_{6} \mathrm{H}_{8} \mathrm{O}_{6}\right)$ is a water-soluble vitamin. A solution containing $80.5 \mathrm{~g}$ of ascorbic acid dissolved in $210 \mathrm{~g}$ of water has a density of $1.22 \mathrm{~g} / \mathrm{mL}$ at $55^{\circ} \mathrm{C}$. Calculate (a) the mass percentage, (b) the mole fraction, $(\mathbf{c})$ the molality, $(\mathbf{d})$ the molarity of ascorbic acid in this solution.

Snow Popis

Numerade Educator

Problem 49

The density of acetonitrile $\left(\mathrm{CH}_{3} \mathrm{CN}\right)$ is $0.786 \mathrm{~g} / \mathrm{mL}$ and the density of methanol $\left(\mathrm{CH}_{3} \mathrm{OH}\right)$ is $0.791 \mathrm{~g} / \mathrm{mL}$. A solution is made by dissolving $25.0 \mathrm{~mL}$ of $\mathrm{CH}_{3} \mathrm{OH}$ in $100 \mathrm{~mL}$ of $\mathrm{CH}_{3} \mathrm{CN}$
(a) What is the mole fraction of methanol in the solution? (b) What is the molality of the solution? (c) Assuming that the volumes are additive, what is the molarity of $\mathrm{CH}_{3} \mathrm{OH}$ in the solution?

Sima Sarker

Numerade Educator

Problem 50

The density of toluene $\left(\mathrm{C}_{7} \mathrm{H}_{8}\right)$ is $0.867 \mathrm{~g} / \mathrm{mL},$ and the density of thiophene $\left(\mathrm{C}_{4} \mathrm{H}_{4} \mathrm{~S}\right)$ is $1.065 \mathrm{~g} / \mathrm{mL}$. A solution is made by dissolving $8.10 \mathrm{~g}$ of thiophene in $250.0 \mathrm{~mL}$ of toluene.
(a) Calculate the mole fraction of thiophene in the solution.
(b) Calculate the molality of thiophene in the solution.
(c) Assuming that the volumes of the solute and solvent are additive, what is the molarity of thiophene in the solution?

Shubham Kumar

Numerade Educator

Problem 51

Calculate the number of moles of solute present in each of the following aqueous solutions:
(a) $750 \mathrm{~mL}$ of $0.120 \mathrm{M}$ $\operatorname{SrBr}_{2},(\mathbf{b}) 70.0 \mathrm{~g}$ of $0.200 \mathrm{~m} \mathrm{KCl},(\mathbf{c}) 150.0 \mathrm{~g}$ of a solution that is $5.75 \%$ glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$ by mass.

Sima Sarker

Numerade Educator

Problem 52

Calculate the number of moles of solute present in each of the following solutions:
(a) $255 \mathrm{~mL}$ of $1.50 \mathrm{M} \mathrm{HNO}_{3}(a q)$
(b) $50.0 \mathrm{mg}$ of an aqueous solution that is $1.50 \mathrm{~m} \mathrm{NaCl}$,
(c) $75.0 \mathrm{~g}$ of an aqueous solution that is $1.50 \%$ sucrose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$ by mass.

Shubham Kumar

Numerade Educator

Problem 53

Describe how you would prepare each of the following aqueous solutions, starting with solid $\mathrm{KBr}$ :
(a) $0.75 \mathrm{~L}$ of $1.5 \times 10^{-2} M \mathrm{KBr},(\mathbf{b}) 125 \mathrm{~g}$ of $0.180 \mathrm{~m} \mathrm{KBr},(\mathbf{c}) 1.85 \mathrm{~L}$ of a solution that is $12.0 \% \mathrm{KBr}$ by mass (the density of the solution is $1.10 \mathrm{~g} / \mathrm{mL}),$ (d) a $0.150 \mathrm{M}$ solution of $\mathrm{KBr}$ that contains just enough $\mathrm{KBr}$ to precipitate $16.0 \mathrm{~g}$ of AgBr from a solution containing $0.480 \mathrm{~mol}$ of $\mathrm{AgNO}_{3}$.

Nadia Lara

Numerade Educator

Problem 54

Describe how you would prepare each of the following aqueous solutions: $(\mathbf{a}) 1.50 \mathrm{~L}$ of $0.110 \mathrm{M}\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$ solution, starting with solid $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4} ;(\mathbf{b}) 225 \mathrm{~g}$ of a solution that is $0.65 \mathrm{~m}$ in $\mathrm{Na}_{2} \mathrm{CO}_{3},$ starting with the solid solute; $(\mathbf{c}) 1.20$ $\mathrm{L}$ of a solution that is $15.0 \% \mathrm{~Pb}\left(\mathrm{NO}_{3}\right)_{2}$ by mass (the density of the solution is $1.16 \mathrm{~g} / \mathrm{mL}$ ), starting with solid solute; (d) a $0.50 \mathrm{M}$ solution of $\mathrm{HCl}$ that would just neutralize $5.5 \mathrm{~g}$ of $\mathrm{Ba}(\mathrm{OH})_{2}$ starting with $6.0 \mathrm{MHCl}$.

Joanna Josey

Numerade Educator

Problem 55

Commercial aqueous nitric acid has a density of $1.12 \mathrm{~g} / \mathrm{mL}$ and is 3.7 M. Calculate the percent $\mathrm{HNO}_{3}$ by mass in the solution.

Sima Sarker

Numerade Educator

Problem 56

Commercial concentrated aqueous ammonia is $28 \% \mathrm{NH}_{3}$ by mass and has a density of $0.90 \mathrm{~g} / \mathrm{mL}$. What is the molarity of this solution?

Joanna Josey

Numerade Educator

Problem 57

Brass is a substitutional alloy consisting of a solution of copper and zinc. A particular sample of yellow brass consisting of $65.0 \%$ Cu and $35.0 \%$ Zn by mass has a density of $8470 \mathrm{~kg} / \mathrm{m}^{3}$. (a) What is the molality of $\mathrm{Zn}$ in the solid solution? (b) What is the molarity of $Z n$ in the solution?

Sima Sarker

Numerade Educator

Problem 58

Caffeine $\left(\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{~N}_{4} \mathrm{O}_{2}\right)$ is a stimulant found in coffee and tea. If a solution of caffeine in the solvent chloroform $\left(\mathrm{CHCl}_{3}\right)$ has a concentration of $0.0500 \mathrm{~m},$ calculate (a) the percentage of caffeine by mass, $(\mathbf{b})$ the mole fraction of caffeine in the solution.

Joanna Josey

Numerade Educator

Problem 59

During a person's typical breathing cycle, the $\mathrm{CO}_{2}$ concentration in the expired air rises to a peak of $4.6 \%$ by volume. (a) Calculate the partial pressure of the $\mathrm{CO}_{2}$ in the expired air at its peak, assuming $101.3 \mathrm{kPa}$ pressure and a body temperature of $37^{\circ} \mathrm{C}$. (b) What is the molarity of the $\mathrm{CO}_{2}$ in the expired air at its peak, assuming a body temperature of $37^{\circ} \mathrm{C} ?$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 60

Breathing air that contains $4.0 \%$ by volume $\mathrm{CO}_{2}$ over time causes rapid breathing, throbbing headache, and nausea, among other symptoms. What is the concentration of $\mathrm{CO}_{2}$ in such air in terms of (a) mol percentage, (b) molarity, assuming 101.3 kPa pressure and a body temperature of $37^{\circ} \mathrm{C} ?$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 61

You make two solutions of a nonvolatile solute with a liquid solvent, $0.01 \mathrm{M}$ and $1.00 \mathrm{M}$. Indicate whether each of the following statements is true or false. (a) The vapor pressure of the concentrated solution is higher than that of the diluted solution. (b) The osmotic pressure of the concentrated solution is higher than that of the diluted solution. (c) The boiling point of the concentrated solution is higher than that of the diluted solution. (d) The freezing point of the concentrated solution is higher than that of the diluted solution.

Sima Sarker

Numerade Educator

Problem 62

You make a solution of a nonvolatile solute with a liquid solvent. Indicate if each of the following statements is true or false. (a) The freezing point of the solution is unchanged by addition of the solvent. (b) The solid that forms as the solution freezes is nearly pure solute. (c) The freezing point of the solution is independent of the concentration of the solute. (d) The boiling point of the solution increases in proportion to the concentration of the solute. (e) At any temperature, the vapor pressure of the solvent over the solution is lower than what it would be for the pure solvent.

Joanna Josey

Numerade Educator

Problem 63

Consider two solutions, one formed by adding $150 \mathrm{~g}$ of glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$ to $1 \mathrm{~L}$ of water and the other formed by adding $150 \mathrm{~g}$ of sucrose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$ to $1 \mathrm{~L}$ of water. Calculate the vapor pressure for each solution at $25^{\circ} \mathrm{C} ;$ the vapor pressure of pure water at this temperature is $3.17 \mathrm{kPa}$.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 64

The vapor pressure of pure water at $70^{\circ} \mathrm{C}$ is $31.2 \mathrm{kPa}$. The vapor pressure of water over a solution at $70^{\circ} \mathrm{C}$ containing equal numbers of moles of water and glycerol $\left(\mathrm{C}_{3} \mathrm{H}_{5}(\mathrm{OH})_{3}\right.$, a nonvolatile solute) is $13.3 \mathrm{kPa}$. Is the solution ideal according to Raoult's law?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 65

(a) Calculate the vapor pressure of water above a solution prepared by adding $22.5 \mathrm{~g}$ of lactose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$ to $200.0 \mathrm{~g}$ of water at $338 \mathrm{~K}$. (Vapor-pressure data for water are given in Appendix B.) (b) Calculate the mass of propylene glycol $\left(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}_{2}\right)$ that must be added to $0.340 \mathrm{~kg}$ of water to reduce the vapor pressure by $384 \mathrm{~Pa}$ at $40^{\circ} \mathrm{C}$.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 66

(a) Calculate the vapor pressure of water above a solution prepared by dissolving $28.5 \mathrm{~g}$ of glycerin $\left(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}_{3}\right)$ in $125 \mathrm{~g}$ of water at $343 \mathrm{~K}$. (The vapor pressure of water is given in Appendix B.) (b) Calculate the mass of ethylene glycol $\left(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}\right)$ that must be added to $1.00 \mathrm{~kg}$ of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ to reduce its vapor pressure by $1.33 \mathrm{kPa}$ at $35^{\circ} \mathrm{C}$.
The vapor pressure of pure ethanol at $35^{\circ} \mathrm{C}$ is $13.3 \mathrm{kPa}$.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 67

At $63.5^{\circ} \mathrm{C}$, the vapor pressure of $\mathrm{H}_{2} \mathrm{O}$ is $23.3 \mathrm{kPa}$, and that of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ is $53.3 \mathrm{kPa}$. A solution is made by mixing equal masses of $\mathrm{H}_{2} \mathrm{O}$ and $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$. (a) What is the mole fraction of ethanol in the solution? (b) Assuming idealsolution behavior, what is the vapor pressure of the solution at $63.5^{\circ} \mathrm{C} ?(\mathbf{c})$ What is the mole fraction of ethanol in the vapor above the solution?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 68

At $20^{\circ} \mathrm{C}$, the vapor pressure of benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ is $10 \mathrm{kPa}$, and that of toluene $\left(\mathrm{C}_{7} \mathrm{H}_{8}\right)$ is $2.9 \mathrm{kPa}$. Assume that benzene and toluene form an ideal solution. (a) What is the composition in mole fraction of a solution that has a vapor pressure of $4.7 \mathrm{kPa}$ at $20^{\circ} \mathrm{C} ?$ (b) What is the mole fraction of benzene in the vapor above the solution described in part (a)?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 69

(a) Does a $0.10 \mathrm{~m}$ aqueous solution of $\mathrm{KCl}$ have a higher freezing point, a lower freezing point, or the same freezing point as a $0.10 \mathrm{~m}$ aqueous solution of urea $\left(\mathrm{CO}\left(\mathrm{NH}_{2}\right)_{2}\right)$,
(b) The experimental freezing point of the KCl solution is higher than that calculated assuming that $\mathrm{KCl}$ is completely dissociated in solution. Why is this the case?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 70

Arrange the following aqueous solutions, each $10 \%$ by mass in solute, in order of increasing boiling point: glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right),$ sucrose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right),$ sodium nitrate $\left(\mathrm{NaNO}_{3}\right)$.

Joanna Josey

Numerade Educator

Problem 71

List the following aqueous solutions in order of increasing boiling point: $0.080 \mathrm{~m} \mathrm{KBr}, 0.130 \mathrm{~m}$ urea $\left(\mathrm{CO}\left(\mathrm{NH}_{2}\right)_{2}\right)$, $0.080 \mathrm{~m} \mathrm{Mg}\left(\mathrm{NO}_{2}\right)_{2}$ $0.030 \mathrm{~m}$ phenol $\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OH}\right)$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 72

List the following aqueous solutions in order of decreasing freezing point: $0.040 \mathrm{~m}$ glycerin $\left(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}_{3}\right), 0.020 \mathrm{~m} \mathrm{KBr}$,

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 73

Using data from Table 13.3, calculate the freezing and boiling points of each of the following solutions: (a) $0.22 m$ glycerol $\left(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}_{3}\right)$ in ethanol, $(\mathbf{b}) 0.240 \mathrm{~mol}$ of naphthalene $\left(\mathrm{C}_{10} \mathrm{H}_{8}\right)$ in $2.45 \mathrm{~mol}$ of chloroform, $(\mathbf{c}) 1.50 \mathrm{~g} \mathrm{NaCl}$ in $0.250 \mathrm{~kg}$ of water, $(\mathbf{d}) 2.04 \mathrm{~g} \mathrm{KBr}$ and $4.82 \mathrm{~g}$ glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$ in $188 \mathrm{~g}$ of water.

David Collins

Numerade Educator

Problem 74

Using data from Table 13.3, calculate the freezing and boiling points of each of the following solutions: (a) $0.25 \mathrm{~m}$ glucose in ethanol; $(\mathbf{b}) 20.0 \mathrm{~g}$ of decane, $\mathrm{C}_{10} \mathrm{H}_{22},$ in $50.0 \mathrm{~g}$ $\mathrm{CHCl}_{3} ;$ (c) $3.50 \mathrm{~g} \mathrm{NaOH}$ in $175 \mathrm{~g}$ of water, (d) 0.45 mol ethylene glycol and $0.15 \mathrm{~mol} \mathrm{KBr}$ in $150 \mathrm{~g} \mathrm{H}_{2} \mathrm{O}$.

Shubham Kumar

Numerade Educator

Problem 75

How many grams of ethylene glycol $\left(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}\right)$ must be added to $2.00 \mathrm{~kg}$ of water to produce a solution that freezes at $-10.00^{\circ} \mathrm{C} ?$

Sima Sarker

Numerade Educator

Problem 76

What is the freezing point of an aqueous solution that boils at $105.0^{\circ} \mathrm{C} ?$

Snow Popis

Numerade Educator

Problem 77

What is the osmotic pressure formed by dissolving $50.0 \mathrm{mg}$ of acetylsalicylic acid $\left(\mathrm{C}_{9} \mathrm{H}_{8} \mathrm{O}_{4}\right)$ in $0.100 \mathrm{~L}$ of water at $37^{\circ} \mathrm{C} ?$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 78

The Baltic Sea has a salinity of $1.0 \%$, that is, its water contains $10 \mathrm{~g}$ of salt for every liter of solution. Assuming that the solute consists entirely of $\mathrm{NaCl}$ (in fact, over $90 \%$ of the salt is indeed $\mathrm{NaCl}$ ), calculate the osmotic pressure of this seawater at $15^{\circ} \mathrm{C}$.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 79

Adrenaline is the hormone that triggers the release of extra glucose molecules in times of stress or emergency. A solution of $0.64 \mathrm{~g}$ of adrenaline in $36.0 \mathrm{~g}$ of $\mathrm{CCl}_{4}$ elevates the boiling point by $0.49^{\circ} \mathrm{C}$. Calculate the approximate molar mass of adrenaline from this data.

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 80

Lauryl alcohol is obtained from coconut oil and is used to make detergents. A solution of $5.00 \mathrm{~g}$ of lauryl alcohol in $0.100 \mathrm{~kg}$ of benzene freezes at $4.1^{\circ} \mathrm{C}$. What is the molar mass of lauryl alcohol from this data?

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 81

Lysozyme is an enzyme that breaks bacterial cell walls. A solution containing $0.150 \mathrm{~g}$ of this enzyme in $210 \mathrm{~mL}$ of solution has an osmotic pressure of $0.127 \mathrm{kPa}$ at $25^{\circ} \mathrm{C}$. What is the molar mass of lysozyme?

Sima Sarker

Numerade Educator

Problem 82

A dilute aqueous solution of fructose in water is formed by dissolving $1.25 \mathrm{~g}$ of the compound in water to form $0.150 \mathrm{~L}$ of solution. The resulting solution has an osmotic pressure of $112.8 \mathrm{kPa}$ at $20^{\circ} \mathrm{C}$. Assuming that the organic compound is a nonelectrolyte, what is its molar mass?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 83

The osmotic pressure of a $0.010 \mathrm{M}$ aqueous solution of $\mathrm{CaCl}_{2}$ is found to be $68.3 \mathrm{kPa}$ at $25^{\circ} \mathrm{C}$. Calculate the van't Hoff factor, $i$, for the solution.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 84

Based on the data given in Table $13.4,$ which solution would give the larger freezing-point lowering, a $0.030 \mathrm{~m}$ solution of $\mathrm{NaCl}$ or a $0.020 \mathrm{~m}$ solution of $\mathrm{K}_{2} \mathrm{SO}_{4} ?$

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 85

(a) Do colloids made only of gases exist? Why or why not? (b) In the 1850s, Michael Faraday prepared ruby-red colloids of gold nanoparticles in water that are still stable today. These brightly colored colloids look like solutions. What experiment(s) could you do to determine whether a given colored preparation is a solution or colloid?

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 86

Choose the best answer: A colloidal dispersion of one liquid in another is called $(\mathbf{a})$ a gel, $(\mathbf{b})$ an emulsion, $(\mathbf{c})$ a foam (d) an aerosol.

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 87

An "emulsifying agent" is a compound that helps stabilize a hydrophobic colloid in a hydrophilic solvent (or a hydrophilic colloid in a hydrophobic solvent). Which of the following choices is the best emulsifying agent?
(a) $\mathrm{CH}_{3} \mathrm{COOH},$
(b) $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{COOH},$
(c) $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{11}$ COOH,
(d) $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{11} \mathrm{COONa}$.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 88

Aerosols are important components of the atmosphere. Does the presence of aerosols in the atmosphere increase or decrease the amount of sunlight that arrives at the Earth's surface, compared to an "aerosol-free" atmosphere? Explain your reasoning.

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 89

Proteins can be precipitated out of aqueous solution by the addition of an electrolyte; this process is called "salting out" the protein. (a) Do you think that all proteins would be precipitated out to the same extent by the same concentration of the same electrolyte? (b) If a protein has been salted out, are the protein-protein interactions stronger or weaker than they were before the electrolyte was added?
(c) A friend of yours who is taking a biochemistry class says that salting out works because the waters of hydration that surround the protein prefer to surround the electrolyte as the electrolyte is added; therefore, the protein's hydration shell is stripped away, leading to protein precipitation. Another friend of yours in the same biochemistry class says that salting out works because the incoming ions adsorb tightly to the protein, making ion pairs on the protein surface, which end up giving the protein a zero net charge in water and therefore leading to precipitation. Discuss these two hypotheses. What kind of measurements would you need to make to distinguish between these two hypotheses?

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 90

Soaps consist of compounds such as sodium stearate, $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{16} \mathrm{COO}^{-} \mathrm{Na}^{+},$ that have both hydrophobic and hydrophilic parts. Consider the hydrocarbon part of sodium stearate to be the "tail" and the charged part to be the "head."
(a) Which part of sodium stearate, head or tail, is more likely to be solvated by water?
(b) Grease is a complex mixture of (mostly) hydrophobic compounds. Which part of sodium stearate, head or tail, is most likely to bind to grease?
(c) If you have large deposits of grease that you want to wash away with water, you can see that adding sodium stearate will help you produce an emulsion. What intermolecular interactions are responsible for this?

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 91

The "free-base" form of cocaine $\left(\mathrm{C}_{17} \mathrm{H}_{21} \mathrm{NO}_{4}\right)$ and its protonated hydrochloride form $\left(\mathrm{C}_{17} \mathrm{H}_{22} \mathrm{ClNO}_{4}\right)$ are shown below; the free-base form can be converted to the hydrochloride form with one equivalent of HCl. For clarity, not all the carbon and hydrogen atoms are shown; each vertex represents a carbon atom with the appropriate number of hydrogen atoms so that each carbon makes four bonds to other atoms.
(a) One of these forms of cocaine is relatively water-soluble:
which form, the free base or the hydrochloride?
(b) One of these forms of cocaine is relatively insoluble in water: which form, the free base or the hydrochloride?
(c) The free-base form of cocaine has a solubility of $1.00 \mathrm{~g}$ in $6.70 \mathrm{~mL}$ ethanol $\left(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\right) .$ Calculate the molarity of a saturated solution of the free-base form of cocaine in ethanol.
(d) The hydrochloride form of cocaine has a solubility of $1.00 \mathrm{~g}$ in $0.400 \mathrm{~mL}$ water. Calculate the molarity of a saturated solution of the hydrochloride form of cocaine in water.
(e) How many mL of a concentrated $18.0 \mathrm{M} \mathrm{HCl}$ aqueous solution would it take to convert 1.00 kilograms (a "kilo") of the free-base form of cocaine into its hydrochloride form?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 92

A supersaturated solution of sucrose $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$ is made by dissolving sucrose in hot water and slowly letting the solution cool to room temperature. After a long time, the excess sucrose crystallizes out of the solution. Indicate whether each of the following statements is true or false:
(a) After the excess sucrose has crystallized out, the remaining solution is saturated.
(b) After the excess sucrose has crystallized out, the system is now unstable and is not in equilibrium.
(c) After the excess sucrose has crystallized out, the rate of sucrose molecules leaving the surface of the crystals to be hydrated by water is equal to the rate of sucrose molecules in water attaching to the surface of the crystals.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 93

Some soft drinks contain up to 85 ppm oxygen. (a) What is this concentration in mol/L? (b) What partial pressure of $\mathrm{O}_{2}$ above water is needed to obtain $85 \mathrm{ppm} \mathrm{O}_{2}$ in water at $10^{\circ} \mathrm{C} ?$ (The Henry's law constant for $\mathrm{O}_{2}$ at this temperature is $\left.1.69 \times 10^{-5} \mathrm{~mol} / \mathrm{m}^{3}-\mathrm{Pa} .\right)$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 94

The presence of the radioactive gas radon $(\mathrm{Rn})$ in well water presents a possible health hazard in parts of the United States. (a) Assuming that the solubility of radon in water with 15.2 kPa pressure of the gas over the water at $30^{\circ} \mathrm{C}$ is $0.109 \mathrm{M},$ what is the Henry's law constant for radon in water at this temperature? (b) A sample consisting of various gases contains 4.5 -ppm radon (mole fraction). This gas at a total pressure of 5.07 MPa is shaken with water at $30^{\circ} \mathrm{C} .$ Calculate the molar concentration of radon in the water.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 95

Glucose makes up about $0.10 \%$ by mass of human blood. Calculate this concentration in (a) ppm, (b) molality.
(c) What further information would you need to determine the molarity of the solution?

Nadia Lara

Numerade Educator

Problem 96

The concentration of gold in seawater has been reported to be between 5 ppt (parts per trillion) and 50 ppt. Assuming that seawater contains 13 ppt of gold, calculate the number of grams of gold contained in $1.0 \times 10^{3}$ gal of seawater.

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 97

The maximum allowable concentration of lead in drinking water is 9.0 ppb. (a) Calculate the molarity of lead in a 9.0ppb solution. (b) How many grams of lead are in a swimming pool containing 9.0 ppb lead in $60 \mathrm{~m}^{3}$ of water?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 98

Acetonitrile $\left(\mathrm{CH}_{3} \mathrm{CN}\right)$ is a polar organic solvent that dissolves a wide range of solutes, including many salts. The density of a $1.80 \mathrm{M}$ LiBr solution in acetonitrile is $0.826 \mathrm{~g} / \mathrm{cm}^{3}$. Calculate the concentration of the solution in (a) molality, (b) mole fraction of LiBr, (c) mass percentage of $\mathrm{CH}_{3} \mathrm{CN}$.

Banhishikha Sinha

Banhishikha Sinha

Numerade Educator

Problem 99

A "canned heat" product used to warm buffet dishes consists of a homogeneous mixture of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ and paraffin, which has an average formula of $\mathrm{C}_{24} \mathrm{H}_{50}$. What mass of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$ should be added to $620 \mathrm{~kg}$ of the paraffin to produce $1.07 \mathrm{kPa}$ of ethanol vapor pressure at $35^{\circ} \mathrm{C}$ ? The vapor pressure of pure ethanol at $35^{\circ} \mathrm{C}$ is $13.3 \mathrm{kPa}$.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 100

A solution contains $0.50 \mathrm{~mol} \mathrm{H}_{2} \mathrm{O}$ and an unknown number of moles of sodium chloride. The vapor pressure of the solution at $29^{\circ} \mathrm{C}$ is $3.85 \mathrm{kPa}$. The vapor pressure of pure water at this temperature is $4.05 \mathrm{kPa}$. Calculate the number of grams of sodium chloride in the solution. (Hint: Remember that sodium chloride is a strong electrolyte.)

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 101

Two beakers are placed in a sealed box at $25^{\circ} \mathrm{C}$. One beaker contains $50.0 \mathrm{~mL}$ of a $0.050 \mathrm{M}$ aqueous solution of a $\mathrm{NaCl}$. The other beaker contains $50.0 \mathrm{~mL}$ of a $0.040 \mathrm{M}$ aqueous solution of $\mathrm{CaCl}_{2}$. The water vapor pressure of the two solutions reaches equilibrium.
(a) In which beaker does the solution level rise, and in which one does it fall?
(b) What are the volumes in the two beakers when equilibrium is attained, assuming ideal behavior?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 102

The normal boiling point of ethanol, $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH},$ is $78.4^{\circ} \mathrm{C}$. When $3.26 \mathrm{~g}$ of a soluble nonelectrolyte is dissolved in $100.0 \mathrm{~g}$ of ethanol at that temperature, the vapor pressure of the solution is $100 \mathrm{kPa}$. What is the molar mass of the solute?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 103

Calculate the freezing point of a $0.100 m$ aqueous solution of $\mathrm{K}_{2} \mathrm{SO}_{4},$ (a) ignoring interionic attractions, and (b) taking interionic attractions into consideration by using the van't Hoff factor (Table 13.4).

Ricajoy Montero

Ricajoy Montero

Numerade Educator

Problem 104

Benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ boils at $80.1^{\circ} \mathrm{C}$ and has a density of $0.876 \mathrm{~g} / \mathrm{mL} .$ (a) When $0.100 \mathrm{~mol}$ of a nondissociating solute is dissolved in $500 \mathrm{~mL}$ of $\mathrm{C}_{6} \mathrm{H}_{6}$, the solution boils at $79.52^{\circ} \mathrm{C}$. What is the molal boiling-point-elevation constant for $\mathrm{C}_{6} \mathrm{H}_{6} ?$ (b) When $10.0 \mathrm{~g}$ of a nondissociating unknown is dissolved in $500 \mathrm{~mL}$ of $\mathrm{C}_{6} \mathrm{H}_{6}$, the solution boils at $79.23^{\circ} \mathrm{C}$. What is the molar mass of the unknown?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 105

A lithium salt used in lubricating grease has the formula $\mathrm{LiC}_{n} \mathrm{H}_{2 n+1} \mathrm{O}_{2}$. The salt is soluble in water to the extent of $0.036 \mathrm{~g}$ per $100 \mathrm{~g}$ of water at $25^{\circ} \mathrm{C}$. The osmotic pressure of this solution is found to be $7.61 \mathrm{kPa}$. Assuming that molality and molarity in such a dilute solution are the same and that the lithium salt is completely dissociated in the solution, determine an appropriate value of $n$ in the formula for the salt.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 106

Fluorocarbons (compounds that contain both carbon and fluorine) were, until recently, used as refrigerants. The compounds listed in the following table are all gases at $25^{\circ} \mathrm{C}$, and their solubilities in water at $25^{\circ} \mathrm{C}$ and 101.3 kPa fluorocarbon pressure are given as mass percentages. (a) For each fluorocarbon, calculate the molality of a saturated solution. (b) Which molecular property best predicts the solubility of these gases in water: molar mass, dipole moment, or ability to hydrogen-bond to water? (c) Infants born with severe respiratory problems are sometimes given liquid ventilation: They breathe a liquid that can dissolve more oxygen than air can hold. One of these liquids is a fluorinated compound, $\mathrm{CF}_{3}\left(\mathrm{CF}_{2}\right)_{7} \mathrm{Br}$. The solubility of oxygen in this liquid is $66 \mathrm{~mL} \mathrm{O}_{2}$ per $100 \mathrm{~mL}$ liquid. In contrast, air is $21 \%$ oxygen by volume. Calculate the moles of $\mathrm{O}_{2}$ present in an infant's lungs (volume: $15 \mathrm{~mL}$ ) if the infant takes a full breath of air compared to taking a full "breath" of a saturated solution of $\mathrm{O}_{2}$ in the fluorinated liquid. Assume a pressure of $101.3 \mathrm{kPa}$ in the lungs.
$$
\begin{array}{lc}
\hline \text { Fluorocarbon } & \text { Solubility (mass \%) } \\
\hline \mathrm{CF}_{4} & 0.0015 \\
\mathrm{CClF}_{3} & 0.009 \\
\mathrm{CCl}_{2} \mathrm{~F}_{2} & 0.028 \\
\mathrm{CHClF}_{2} & 0.30 \\
\hline
\end{array}
$$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 107

At ordinary body temperature $\left(37^{\circ} \mathrm{C}\right),$ the solubility of $\mathrm{N}_{2}$ in water at ordinary atmospheric pressure is $0.015 \mathrm{~g} / \mathrm{L}$ Air is approximately $78 \mathrm{~mol} \% \mathrm{~N}_{2}$.
(a) Calculate the number of moles of $\mathrm{N}_{2}$ dissolved per liter of blood, assuming blood is a simple aqueous solution. (b) At a depth of $30.5 \mathrm{~m}$ in water, the external pressure is $405 \mathrm{kPa}$. What is the solubility of $\mathrm{N}_{2}$ from air in blood at this pressure? (c) If a scuba diver suddenly surfaces from this depth, how many milliliters of $\mathrm{N}_{2}$ gas, in the form of tiny bubbles, are released into the bloodstream from each liter of blood?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 108

Consider the following values for enthalpy of vaporization $(\mathrm{kJ} / \mathrm{mol})$ of several organic substances:
(a) Account for the variations in heats of vaporization for these substances, considering their relative intermolecular forces. $(\mathbf{b})$ How would you expect the solubilities of these substances to vary in hexane as solvent? In ethanol? Use intermolecular forces, including hydrogenbonding interactions where applicable, to explain your responses.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 109

A series of anions is shown below:
The anion on the far right is called "BARF" by chemists, as its common abbreviation sounds similar to this word.
(a) What is the central atom and the number of electronpair domains around the central atom in each of these anions?
(b) What is the electron-domain geometry around the central B in BARF?
(c) Which, if any, of these anions has an expanded octet around its central atom?
(d) Tetrabutylammonium, $\left(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2}\right)_{4} \mathrm{~N}^{+}$ is a bulky cation. Which anion, when paired with the tetrabutylammonium cation, would lead to a salt that will be most soluble in nonpolar solvents?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 110

(a) A sample of hydrogen gas is generated in a closed container by reacting $1.750 \mathrm{~g}$ of zinc metal with $50.0 \mathrm{~mL}$ of $1.00 \mathrm{M}$ hydrochloric acid. Write the balanced equation for the reaction, and calculate the number of moles of hydrogen formed, assuming that the reaction is complete.
(b) The volume over the solution in the container is 150 mL. Calculate the partial pressure of the hydrogen gas in this volume at $25^{\circ} \mathrm{C}$, ignoring any solubility of the gas in the solution. (c) The Henry's law constant for hydrogen in water at $25^{\circ} \mathrm{C}$ is $7.7 \times 10^{-6} \mathrm{~mol} / \mathrm{m}^{3}-\mathrm{Pa}$. Estimate the
number of moles of hydrogen gas that remain dissolved in the solution. What fraction of the gas molecules in the system is dissolved in the solution? Was it reasonable to ignore any dissolved hydrogen in part (b)?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 111

The following table presents the solubilities of several gases in water at $25^{\circ} \mathrm{C}$ under a total pressure of gas and water vapor of 101.3 kPa. (a) What volume of $\mathrm{CH}_{4}(g)$ under standard conditions of temperature and pressure is contained in $4.0 \mathrm{~L}$ of a saturated solution at $25^{\circ} \mathrm{C} ?$
(b) The solubilities (in water) of the hydrocarbons are as follows: methane $<$ ethane $<$ ethylene. Is this because ethylene is the most polar molecule?
(c) What intermolecular interactions can these hydrocarbons have with water? (d) Draw the Lewis dot structures for the three hydrocarbons. Which of these hydrocarbons possess $\pi$ bonds? Based on their solubilities, would you say $\pi$ bonds are more or less polarizable than $\sigma$ bonds? (e) Explain why NO is more soluble in water than either $\mathrm{N}_{2}$ or $\mathrm{O}_{2} .$ (f) $\mathrm{H}_{2} \mathrm{~S}$ is more water-soluble than almost all the other gases in table. What intermolecular forces is $\mathrm{H}_{2} \mathrm{~S}$ likely to have with water? $(\mathbf{g}) \mathrm{SO}_{2}$ is by far the most water-soluble gas in table. What intermolecular forces is $\mathrm{SO}_{2}$ likely to have with water?
$$
\begin{array}{lc}
\hline \text { Gas } & \text { Solubility (mM) } \\
\hline \mathrm{CH}_{4} \text { (methane) } & 1.3 \\
\mathrm{C}_{2} \mathrm{H}_{6} \text { (ethane) } & 1.8 \\
\mathrm{C}_{2} \mathrm{H}_{4} \text { (ethylene) } & 4.7 \\
\mathrm{~N}_{2} & 0.6 \\
\mathrm{O}_{2} & 1.2 \\
\mathrm{NO} & 1.9 \\
\mathrm{H}_{2} \mathrm{~S} & 99 \\
\mathrm{SO}_{2} & 1476 \\
\hline
\end{array}
$$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 112

A small cube of sodium (density $\left.=0.968 \mathrm{~g} / \mathrm{cm}^{3}\right)$ measuring $1.0 \mathrm{~mm}$ on each edge is added to $0.100 \mathrm{~L}$ of water. The following reaction occurs:
$$
2 \mathrm{Na}(s)+\mathrm{H}_{2} \mathrm{O} \longrightarrow 2 \mathrm{NaOH}(a q)+\mathrm{H}_{2}(g)
$$
What is the freezing point of the resulting solution, assuming that the reaction goes to completion?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 113

At $35^{\circ} \mathrm{C}$ the vapor pressure of acetone, $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CO},$ is 47.9 $\mathrm{kPa}$, and that of carbon disulfide, $\mathrm{CS}_{2}$, is $66.7 \mathrm{kPa}$. A solution composed of an equal number of moles of acetone and carbon disulfide has a vapor pressure of $86.7 \mathrm{kPa}$ at $35^{\circ} \mathrm{C} .(\mathbf{a})$ What would be the vapor pressure of the solution if it exhibited ideal behavior? (b) Based on the behavior of the solution, predict whether the mixing of acetone and carbon disulfide is an exothermic $\left(\Delta H_{\text {soln }}<0\right)$ or endothermic $\left(\Delta H_{\text {soln }}>0\right)$ process.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 114

Compounds like sodium stearate, called "surfactants" in general, can form structures known as micelles in water, once the solution concentration reaches the value known as the critical micelle concentration (cmc). Micelles contain dozens to hundreds of molecules. The cmc depends on the substance, the solvent, and the temperature.
At and above the $\mathrm{cmc}$, the properties of the solution vary drastically.
(a) The turbidity (the amount of light scattering) of solutions increases dramatically at the $\mathrm{cmc}$. Suggest an explanation. (b) The ionic conductivity of the solution dramatically changes at the $\mathrm{cmc}$. Suggest an explanation.
(c) Chemists have developed fluorescent dyes that glow brightly only when the dye molecules are in a hydrophobic environment. Predict how the intensity of such fluorescence would relate to the concentration of sodium stearate as the sodium stearate concentration approaches and then increases past the $\mathrm{cmc}$.

Susan Hallstrom

Susan Hallstrom

Numerade Educator