Describe how properties of seawater illustrate the two characteristics that define mixtures.

Ali D.

Numerade Educator

What types of intermolecular forces give rise to hydration shells in an aqueous solution of sodium chloride?

Nicole V.

Numerade Educator

Acetic acid is miscible with water. Would you expect carboxylic acids with general formula $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{n} \mathrm{COOH}$ to become more or less water soluble as n increases? Explain.

Ali D.

Numerade Educator

Which would you expect to be more effective as a soap, sodium acetate or sodium stearate? Explain.

Keenan M.

University of Miami

Hexane and methanol are miscible as gases but only slightly soluble in each other as liquids. Explain.

Ali D.

Numerade Educator

Hydrogen chloride (HCl) gas is much more soluble than propane gas $\left(\mathrm{C}_{3} \mathrm{H}_{8}\right)$ in water, even though HCl has a lower boiling point. Explain.

Keenan M.

University of Miami

Which gives the more concentrated solution, (a) $\mathrm{KNO}_{3}$ in $\mathrm{H}_{2} \mathrm{O}$ or ( b ) $\mathrm{KNO}_{3}$ in carbon tetrachloride $\left(\mathrm{CCl}_{4}\right) ?$ Explain.

Ali D.

Numerade Educator

Which gives the more concentrated solution, stearic acid $\left[\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{16} \mathrm{COOH}\right]$ in $(\mathrm{a}) \mathrm{H}_{2} \mathrm{O}$ or $(\mathrm{b}) \mathrm{CCl}_{4} ?$ Explain.

Keenan M.

University of Miami

What is the strongest type of intermolecular force between solute and solvent in each solution?

Ali D.

Numerade Educator

What is the strongest type of intermolecular force between solute and solvent in each solution?

(a) $\mathrm{Cu}(s)$ in $\mathrm{Ag}(s)$ (b) $\mathrm{CH}_{3} \mathrm{Cl}(g)$ in $\mathrm{CH}_{3} \mathrm{OCH}_{3}(g)$

c) $\mathrm{CH}_{3} \mathrm{CH}_{3}(g)$ in $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}(l)$

Keenan M.

University of Miami

What is the strongest type of intermolecular force between solute and solvent in each solution?

(a) $\mathrm{CH}_{3} \mathrm{OCH}_{3}(g)$ in $\mathrm{H}_{2} \mathrm{O}(I)$ (b) $\mathrm{Ne}(g)$ in $\mathrm{H}_{2} \mathrm{O}(l)$

(c) $\mathrm{N}_{2}(g)$ in $\mathrm{C}_{4} \mathrm{H}_{10}(g)$

Ali D.

Numerade Educator

What is the strongest type of intermolecular force between solute and solvent in each solution?

(a) $\mathrm{C}_{6} \mathrm{H}_{14}(l)$ in $\mathrm{C}_{8} \mathrm{H}_{18}(l)$ (b) $\mathrm{H}_{2} \mathrm{C}=\mathrm{O}(g)$ in $\mathrm{CH}_{3} \mathrm{OH}( )$

(c) $\mathrm{Br}_{2}(l)$ in $\mathrm{CCl}_{4}(l)$

Keenan M.

University of Miami

Which member of each pair is more soluble in diethyl ether? Why?

Keenan M.

University of Miami

A dictionary definition of homogeneous is “uniform in composition throughout.” River water is a mixture of dissolved compounds, such as calcium bicarbonate, and suspended soil particles. Is river water homogeneous? Explain.

Ali D.

Numerade Educator

Gluconic acid is a derivative of glucose used in cleaners and in the dairy and brewing industries. Caproic acid is a carboxylic acid used in the flavoring industry. Although both are six-carbon acids (see structures below), gluconic acid is soluble in water and nearly insoluble in hexane, whereas caproic acid has the opposite solubility behavior. Explain

Keenan M.

University of Miami

Name three intermolecular forces that stabilize the shape of a soluble, globular protein, and explain how they act.

Ali D.

Numerade Educator

Name three intermolecular forces that stabilize the structure of DNA, and explain how they act.

Keenan M.

University of Miami

How can relatively weak H bonds hold the double helix together yet allow DNA to function?

Ali D.

Numerade Educator

Is sodium propanoate (the sodium salt of propanoic acid) as effective a soap as sodium stearate (the sodium salt of stearic acid)? Explain.

Keenan M.

University of Miami

In what way do proteins embedded in a membrane differ structurally from soluble proteins?

Keenan M.

University of Miami

Histones are proteins that control gene function by attaching through salt links to exterior regions of DNA. Name an amino acid whose side chain is often found on the exterior of histones.

Ali D.

Numerade Educator

For a general solvent, which enthalpy terms in the thermochemical solution cycle are combined to obtain $\Delta H_{\text { solvation }} ?$

Ali D.

Numerade Educator

a) What is the charge density of an ion, and what two properties of an ion affect it?(b) Arrange the following in order of increasing charge density:

(c) How do the two properties in part (a) affect the ionic heat of hydration, $\Delta H_{\text { hydr }} ?$

Keenan M.

University of Miami

For $\Delta H_{\text { soln to be very small, what quantities must be nearly }}$ equal in magnitude? Will their signs be the same or opposite?

Ali D.

Numerade Educator

Water is added to a flask containing solid $\mathrm{NH}_{4} \mathrm{Cl}$ . As the salt dissolves, the solution becomes colder

(a) Is the dissolving of $\mathrm{NH}_{4} \mathrm{Cl}$ exothermic or endothermic?

(b) Is the magnitude of $\Delta H_{\text { latice }}$ of $\mathrm{NH}_{4}$ Cl larger or smaller than the combined $\Delta H_{\text { hydr }}$ of the ions? Explain.

(c) Given the answer to (a), why does $\mathrm{NH}_{4} \mathrm{Cl}$ dissolve in water?

Keenan M.

University of Miami

Sketch an enthalpy diagram for the process of dissolving $\mathrm{KCl}(s)$ in $\mathrm{H}_{2} \mathrm{O}$ (endothermic).

Keenan M.

University of Miami

Sketch an enthalpy diagram for the process of dissolving $\mathrm{NaI}(s)$ in $\mathrm{H}_{2} \mathrm{O}$ (exothermic).

Ali D.

Numerade Educator

Which ion in each pair has greater charge density? Explain.

(a) ${Na}^{+}$ or ${Cs}^{+}$ (b) ${Sr}^{2+}$ or ${R} {b}^{+}$ (c) ${Na}^{+}$ or ${Cl}^{-}$

(d) ${O}^{2-}$ or ${F}^{-}$ (e) ${OH}^{-}$ or ${SH}^{-}$ (f) ${Mg}^{2+}$ or ${Ba}^{2+}$

(g) ${Mg}^{2+}$ or ${Na}^{+}$ (h) ${NO}_{3}^{-}$ or ${CO}_{3}^{2-}$

Keenan M.

University of Miami

Which ion has the lower ratio of charge to volume? Explain.

(a) ${Br}^{-}$ or ${I}^{-}$ (b) ${Sc}^{3+}$ or ${Ca}^{2+}$ (c) ${Br}^{-}$ or ${K}^{+}$

(d) ${S}^{2-}$ or ${Cl}^{-}$ (e) ${Sc}^{3+}$ or ${Al}^{3+}$ (f) ${SO}_{4}^{2-}$ or ${ClO}_{4}^{-}$

(g) ${Fe}^{3+}$ or ${Fe}^{2+}$ (h) ${Ca}^{2+}$ or ${K}^{+}$

Ali D.

Numerade Educator

Which ion of each pair in Problem 13.32 has the larger $\Delta H_{\mathrm{hydr}} ?$

Keenan M.

University of Miami

Which ion of each pair in Problem 13.33 has the smaller $\Delta H_{\text { bydr }} ?$

Ali D.

Numerade Educator

a) Use the following data to calculate the combined heat of hydration for the ions in potassium bromate (KBrO_ $_{3} ) :$

$$\Delta H_{\text { lattice}}=745 \mathrm{kJ} / \mathrm{mol} \quad \Delta H_{\mathrm{soln}}=41.1 \mathrm{kJ} / \mathrm{mol}$$

(b) Which ion contributes more to the answer for part (a)? Why?

Keenan M.

University of Miami

(a) Use the following data to calculate the combined heat of hydration for the ions in sodium acetate $\left(\mathrm{NaC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)$

$$\Delta H_{\text { lattice }}=763 \mathrm{kJ} / \mathrm{mol} \quad \Delta H_{\mathrm{soln}}=17.3 \mathrm{kJ} / \mathrm{mol}$$

(b) Which ion contributes more to the answer for part (a)? Why?

Ali D.

Numerade Educator

State whether the entropy of the system increases or decreases in each of the following processes:

(a) Pure gases are mixed to prepare an anesthetic.

(b) Electronic-grade silicon is prepared from sand

(c) Dry ice (solid $\mathrm{CO}_{2} )$ sublimes.

Ali D.

Numerade Educator

Besides its use in making black-and-white film, silver nitrate $\left(\mathrm{AgNO}_{3}\right)$ is used similarly in forensic science. The NaCl left behind in the sweat of a fingerprint is treated with AgNO_ solution o form AgCl. This precipitate is developed to show the blackand-white fingerprint pattern. Given that $\Delta H_{\text { lattice }}=822 \mathrm{kJ} / \mathrm{mol}$ and $\Delta H_{\mathrm{hydr}}=$ $-799 \mathrm{kJ} / \mathrm{mol}$ for $\mathrm{AgNO}_{3},$ calculate its $\Delta H_{\mathrm{soln}}$

Keenan M.

University of Miami

You are given a bottle of solid X and three aqueous solutions of X—one saturated, one unsaturated, and one supersaturated. How would you determine which solution is which?

Ali D.

Numerade Educator

Potassium permanganate $\left(\mathrm{KMnO}_{4}\right)$ has a solubility of 6.4 $\mathrm{g} / 100 \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O}$ at $20^{\circ} \mathrm{C}$ and a curve of solubility vs. temperature that slopes upward to the right. How would you prepare a supersaturated solution of $\mathrm{KMnO}_{4} ?$

Keenan M.

University of Miami

Why does the solubility of any gas in water decrease with rising temperature?

Ali D.

Numerade Educator

For a saturated aqueous solution of each of the following at $20^{\circ} \mathrm{C}$ and 1 atm, will the solubility increase, decrease, or stay the same when the indicated change occurs?

(a) $\mathrm{O}_{2}(g),$ increase $P$ (b) $\mathrm{N}_{2}(g),$ increase $V$

Keenan M.

University of Miami

13.45 For a saturated aqueous solution of each of the following at $20^{\circ} \mathrm{C}$ and 1 $\mathrm{atm}$ , will the solubility increase, decrease, or stay the same when the indicated change occurs?

(a) $\mathrm{He}(g),$ decrease $T$ (b) $\mathrm{RbI}(s),$ increase $P$

Ali D.

Numerade Educator

The Henry's law constant $\left(k_{\mathrm{H}}\right)$ for $\mathrm{O},$ in water at $20^{\circ} \mathrm{C}$ is $1.28 \times 10^{-3} \mathrm{mol} / \mathrm{L} \cdot \mathrm{atm} .$ (a) How many grams of $\mathrm{O}_{2}$ will dissolve in 2.50 $\mathrm{L}$ of $\mathrm{H}_{2} \mathrm{O}$ that is in contact with pure $\mathrm{O}_{2}$ at 1.00 $\mathrm{atm}$ ? (b) How many grams of $\mathrm{O}_{2}$ will dissolve in 2.50 $\mathrm{L}$ of $\mathrm{H}_{2} \mathrm{O}$ that is in contact with air, where the partial pressure of $\mathrm{O}_{2}$ is 0.209 atm?

Keenan M.

University of Miami

Argon makes up 0.93$\%$ by volume of air. Calculate its solubility $(\mathrm{mol} / \mathrm{L})$ in water at $20^{\circ} \mathrm{C}$ and 1.0 $\mathrm{atm}$ . The Henry's law contant for Ar under these conditions is $1.5 \times 10^{-3} \mathrm{mol} / \mathrm{L} \cdot \mathrm{atm}$ .

Ali D.

Numerade Educator

Caffeine is about 10 times as soluble in hot water as in cold water. A chemist puts a hot-water extract of caffeine into an ice bath, and some caffeine crystallizes. Is the remaining solution saturated, unsaturated, or supersaturated?

Keenan M.

University of Miami

The partial pressure of $\mathrm{CO}_{2}$ gas above the liquid in a bottle of champagne at $20^{\circ} \mathrm{C}$ is 5.5 $\mathrm{atm}$ . What is the solubility of $\mathrm{CO}_{2}$ in champagne? Assume Henry's law constant is the same for champagne as for water. at $20^{\circ} \mathrm{C}, k_{\mathrm{H}}=3.7 \times 10^{-2} \mathrm{mol} / \mathrm{L} \cdot$ atm.

Ali D.

Numerade Educator

Respiratory problems are treated with devices that deliver air with a higher partial pressure of $\mathrm{O}_{2}$ than normal air. Why?

Keenan M.

University of Miami

Explain the difference between molarity and molality. Under what circumstances would molality be a more accurate measure of the concentration of a prepared solution than molarity? Why?

Ali D.

Numerade Educator

Which way of expressing concentration includes (a) volume of solution; (b) mass of solution; (c) mass of solvent?

Keenan M.

University of Miami

A solute has a solubility in water of 21 g/kg solvent. Is this value the same as 21 g/kg solution? Explain.

Ali D.

Numerade Educator

You want to convert among molarity, molality, and mole fraction of a solution. You know the masses of solute and solvent and the volume of solution. Is this enough information to carry out all the conversions? Explain.

Keenan M.

University of Miami

When a solution is heated, which ways of expressing concentration change in value? Which remain unchanged? Explain.

Ali D.

Numerade Educator

Calculate the molarity of each aqueous solution:

(a) 32.3 g of table sugar $\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)$ in $100 . \mathrm{mL}$ of solution

(b) 5.80 g of LiNO $_{3}$ in 505 mL of solution

Keenan M.

University of Miami

Calculate the molarity of each aqueous solution:

(a) 0.82 g of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ in 10.5 $\mathrm{mL}$ of solution

(b) 1.27 g of gaseous $\mathrm{NH}_{3}$ in 33.5 $\mathrm{mL}$ of solution

Ali D.

Numerade Educator

Calculate the molarity of each aqueous solution:

(a) 78.0 $\mathrm{mL}$ of 0.240 $\mathrm{M} \mathrm{NaOH}$ diluted to 0.250 $\mathrm{L}$ with water

(b) 38.5 $\mathrm{mL}$ of 1.2 $\mathrm{M} \mathrm{HNO}_{3}$ diluted to 0.130 $\mathrm{L}$ with water

Keenan M.

University of Miami

Calculate the molarity of each aqueous solution:

(a) 25.5 $\mathrm{mL}$ of 6.25 $\mathrm{M} \mathrm{HCl}$ diluted to 0.500 $\mathrm{L}$ with water

(b) 8.25 $\mathrm{mL}$ of $2.00 \times 10^{-2} \mathrm{M} \mathrm{KI}$ diluted to 12.0 $\mathrm{mL}$ with water

Ali D.

Numerade Educator

How would you prepare the following aqueous solutions?

(a) 365 $\mathrm{mL}$ of $8.55 \times 10^{-2} \mathrm{M} \mathrm{KH}_{2} \mathrm{PO}_{4}$ from solid $\mathrm{KH}_{2} \mathrm{PO}_{4}$

(b) 465 mL of 0.335$M \mathrm{NaOH}$ from 1.25 $\mathrm{M} \mathrm{NaOH}$

Keenan M.

University of Miami

How would you prepare the following aqueous solutions?

(a) 2.5 $\mathrm{L}$ of 0.65 $\mathrm{M}$ NaCl from solid $\mathrm{NaCl}$

(b) 15.5 $\mathrm{L}$ of 0.3$M$ urea $\left[\left(\mathrm{NH}_{2}\right), \mathrm{C}=\mathrm{O}\right]$ from 2.1 $\mathrm{M}$ urea

Ali D.

Numerade Educator

How would you prepare the following aqueous solutions?

(a) 1.40 $\mathrm{L}$ of 0.288 M KBr from solid $\mathrm{KBr}$

(b) 255 $\mathrm{mL}$ of 0.0856 $\mathrm{M} \mathrm{LiNO}_{3}$ from 0.264 $\mathrm{M} \mathrm{LiNO}_{3}$

Keenan M.

University of Miami

How would you prepare the following aqueous solutions?

(a) 57.5 $\mathrm{mL}$ of $1.53 \times 10^{-3} \mathrm{M} \mathrm{Cr}\left(\mathrm{NO}_{3}\right)_{3}$ from solid $\mathrm{Cr}\left(\mathrm{NO}_{3}\right)_{3}$

(b) $5.8 \times 10^{3} \mathrm{m}^{3}$ of 1.45 $\mathrm{M} \mathrm{NH}_{4} \mathrm{NO}_{3}$ from 2.50 $\mathrm{M} \mathrm{NH}_{4} \mathrm{NO}_{3}$

Ali D.

Numerade Educator

Calculate the molality of the following:

(a) A solution containing 85.4 g of glycine $\left(\mathrm{NH}_{2} \mathrm{CH}_{2} \mathrm{COOH}\right)$ dissolved in 1.270 $\mathrm{kg}$ of $\mathrm{H}_{2} \mathrm{O}$

(b) A solution containing 8.59 g of glycerol $\left(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}_{3}\right)$ in 77.0 $\mathrm{g}$ of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$

Keenan M.

University of Miami

Calculate the molality of the following:

(a) A solution containing 174 $\mathrm{g}$ of $\mathrm{HCl}$ in 757 $\mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O}$

(b) A solution containing 16.5 g of naphthalene $\left(\mathrm{C}_{10} \mathrm{H}_{8}\right)$ in 53.3 $\mathrm{g}$ of benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$

Ali D.

Numerade Educator

What is the molality of a solution consisting of 44.0 mL of benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6} ; d=0.877 \mathrm{g} / \mathrm{mL}\right)$ in 167 $\mathrm{mL}$ of hexane $\left(\mathrm{C}_{6} \mathrm{H}_{14}\right.$ $d=0.660 \mathrm{g} / \mathrm{mL} ) ?$

Keenan M.

University of Miami

What is the molality of a solution consisting of 2.66 mL of carbon tetrachloride $\left(\mathrm{CCl}_{4} ; d=1.59 \mathrm{g} / \mathrm{mL}\right)$ in 76.5 $\mathrm{mL}$ of methylene chloride $\left(\mathrm{CH}_{2} \mathrm{Cl}_{2} ; d=1.33 \mathrm{g} / \mathrm{mL}\right) ?$

Ali D.

Numerade Educator

How would you prepare the following aqueous solutions?

(a) $3.10 \times 10^{2}$ of 0.125$m$ ethylene glycol $\left(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}\right)$ from ethylene glycol and water

(b) 1.20 $\mathrm{kg}$ of 2.20 $\mathrm{mass} \% \mathrm{HNO}_{3}$ from 52.0 $\mathrm{mass} \% \mathrm{HNO}_{3}$

Keenan M.

University of Miami

How would you prepare the following aqueous solutions?

(a) 1.50 $\mathrm{kg}$ of 0.0355 $\mathrm{m}$ ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ from ethanol and water

(b) 445 g of 13.0 mass $\%$ HCl from 34.1 mass $\% \mathrm{HCl}$

Ali D.

Numerade Educator

A solution contains 0.35 mol of isopropanol $\left(\mathrm{C}_{3} \mathrm{H}_{7} \mathrm{OH}\right)$ dissolved in 0.85 mol of water. (a) What is the mole fraction of isopropanol? (b) The mass percent? (c) The molality?

Keenan M.

University of Miami

A solution contains 0.100 mol of NaCl dissolved in 8.60 mol of water. (a) What is the mole fraction of NaCl? (b) The mass percent? (c) The molality?

Ali D.

Numerade Educator

What mass of cesium bromide must be added to 0.500 L of water (d 5=1.00 g/mL) to produce a 0.400 m solution? What are the mole fraction and the mass percent of CsBr?

Keenan M.

University of Miami

What are the mole fraction and the mass percent of a solution made by dissolving 0.30 g of KI in 0.400 L of water (d = 1.00 g/mL)?

Ali D.

Numerade Educator

Calculate the molality, molarity, and mole fraction of $\mathrm{NH}_{3}$ in ordinary household ammonia, which is an 8.00 $\mathrm{mass} \%$ aqueous solution $(d=0.9651 \mathrm{g} / \mathrm{mL})$

Keenan M.

University of Miami

Calculate the molality, molarity, and mole fraction of $\mathrm{NH}_{3}$ in a 28.8 mass $\%$ aqueous solution $(d=1.280 \mathrm{g} / \mathrm{mL})$

Keenan M.

University of Miami

Wastewater from a cement factory contains 0.25 $\mathrm{g}$ of $\mathrm{Ca}^{2+}$ ion and 0.056 g of $\mathrm{Mg}^{2+}$ ion per 100.0 $\mathrm{L}$ of solution. The solution density is 1.001 $\mathrm{g} / \mathrm{mL}$ . Calculate the $\mathrm{Ca}^{2+}$ and $\mathrm{Mg}^{2+}$ concentra-

tions in ppm (by mass).

Keenan M.

University of Miami

An automobile antifreeze mixture is made by mixing equal volumes of ethylene glycol $(d=1.114 \mathrm{g} / \mathrm{mL} ; \mathscr{M}=62.07 \mathrm{g} / \mathrm{mol})$ and water $(d=1.00 \mathrm{g} / \mathrm{mL})$ at $20^{\circ} \mathrm{C}$ . The density of the mixture is 1.070 $\mathrm{g} / \mathrm{mL}$ . Express the concentration of ethylene glycol as:

(a) Volume percent (b) Mass percent (c) Molarity

(d) Molality (e) Mole fraction

Keenan M.

University of Miami

The chemical formula of a solute does not affect the extent of the solution’s colligative properties. What characteristic of a solute does affect these properties? Name a physical property of a solution that is affected by the chemical formula of the solute.

Keenan M.

University of Miami

What is a nonvolatile nonelectrolyte? Why is using this type of solute the simplest way to demonstrate colligative properties?

Ali D.

Numerade Educator

In what sense is a strong electrolyte “strong”? What property of the substance makes it a strong electrolyte?

Keenan M.

University of Miami

Express Raoult’s law in words. Is Raoult’s law valid for a solution of a volatile solute? Explain.

Ali D.

Numerade Educator

What are the most important differences between the phase diagram of a pure solvent and the phase diagram of a solution of that solvent?

Keenan M.

University of Miami

Is the composition of the vapor at the top of a fractionating column different from the composition at the bottom? Explain.

Keenan M.

University of Miami

Is the boiling point of 0.01 m KF(aq) higher or lower than that of 0.01 m glucose(aq)? Explain.

Keenan M.

University of Miami

Which aqueous solution has a boiling point closer to its predicted value, 0.050 m NaF or 0.50 m KCl? Explain.

Keenan M.

University of Miami

Which aqueous solution has a freezing point closer to its predicted value, 0.01$m$ NaBr or 0.01$m \mathrm{MgCl}_{2}$ ? Explain.

Keenan M.

University of Miami

13.87 The freezing point depression constants of the solvents cyclohexane and naphthalene are $20.1^{\circ} \mathrm{C} / m$ and $6.94^{\circ} \mathrm{C} / \mathrm{m},$ respectively. Which solvent would give a more accurate result if you are using freezing point depression to determine the molar mass of a substance that is soluble in either one? Why?

Keenan M.

University of Miami

Classify the following substances as strong electrolytes, weak electrolytes, or nonelectrolytes:

(a) Hydrogen chloride (HCl) (b) Potassium nitrate $\left(\mathrm{KNO}_{3}\right)$

(c) Glucose $({C}_{6} {H}_{12} {O}_{6})$ (d) Ammonia$\left({NH}_{3}\right)$

Keenan M.

University of Miami

Classify the following substances as strong electrolytes, weak electrolytes, or nonelectrolytes:

(a) Sodium permanganate $\left(\mathrm{NaMnO}_{4}\right)$

(b) Acetic acid $\left(\mathrm{CH}_{3} \mathrm{COOH}\right)$

(c) Mechanol $\left(\mathrm{CH}_{3} \mathrm{OH}\right)$

(D) Calcium acetate $\left[\mathrm{Ca}\left(\mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)_{2}\right]$

Keenan M.

University of Miami

How many moles of solute particles are present in 1 L of each of the following aqueous solutions?

a) 0.3$M \mathrm{KBr}$ b) 0.065$M \mathrm{HNO}_{3}$

c) $10^{-4} M \mathrm{KHSO}_{4}$ d) 0.06$M$ ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$

Keenan M.

University of Miami

How many moles of solute particles are present in 1 mL of each of the following aqueous solutions?

a) 0.02$M \mathrm{CuSO}_{4}$ b) 0.004$M \mathrm{Ba}(\mathrm{OH})_{2}$

c) 0.08$M$ pyridine $\left(\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{N}\right)$ d) 0.05$M\left(\mathrm{NH}_{4}\right)_{2} \mathrm{CO}_{3}$

Keenan M.

University of Miami

Which solution has the lower freezing point?

(a) 11.0 $\mathrm{g}$ of $\mathrm{CH}_{3} \mathrm{OH}$ in 100. g of $\mathrm{H}_{2} \mathrm{O}$ or 22.0 $\mathrm{g}$ of $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$ in $200 . \mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O}$

(b) 20.0 $\mathrm{g}$ of $\mathrm{H}_{2} \mathrm{O}$ in 1.00 $\mathrm{kg}$ of $\mathrm{CH}_{3} \mathrm{OH}$ or 20.0 $\mathrm{g}$ of $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}$ in 1.00 $\mathrm{kg}$ of $\mathrm{CH}_{3} \mathrm{OH}$

Keenan M.

University of Miami

Which solution has the higher boiling point?

(a) 38.0 $\mathrm{g}$ of $\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}_{3}$ in $250 .$ g of ethanol or

38.0 $\mathrm{g}$ of $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}$ in $250 . \mathrm{g}$ of ethanol

(b) 15 $\mathrm{g}$ of $\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}$ in 0.50 $\mathrm{kg}$ of $\mathrm{H}_{2} \mathrm{O}$ or 15 $\mathrm{g}$ of $\mathrm{NaCl}$ in 0.50 $\mathrm{kg}$ of $\mathrm{H}_{2} \mathrm{O}$

Keenan M.

University of Miami

Rank the following aqueous solutions in order of increasing (a) osmotic pressure; (b) boiling point; (c) freezing point; (d) vapor pressure at $50^{\circ} \mathrm{C}$ :

(1) 0.100 $\mathrm{m}$ NaNO,

(II) 0.100 $\mathrm{m}$ glucose

(III) 0.100 $\mathrm{m} \mathrm{CaCl}_{2}$

Keenan M.

University of Miami

Rank the following aqueous solutions in order of decreasing (a) osmotic pressure; (b) boiling point; (c) freezing point; (d) vapor pressure at 298 K:

(1) 0.04 $m$ urea $\left[\left(\mathrm{NH}_{2}\right)_{2} \mathrm{C}=\mathrm{O}\right]$

(I) 0.01 $\mathrm{m} \mathrm{AgNO}_{3}$

(III) 0.03 $\mathrm{m} \mathrm{CuSO}_{4}$

Keenan M.

University of Miami

Calculate the vapor pressure of a solution of 34.0 g of glycerol $\left(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}_{3}\right)$ in 500.0 $\mathrm{g}$ of water at 25 $\mathrm{C}$ . The vapor pressure of

water at $25^{\circ} \mathrm{C}$ is 23.76 torr. (Assume ideal behavior.)

Keenan M.

University of Miami

Calculate the vapor pressure of a solution of 0.39 $\mathrm{mol}$ of cholesterol in 5.4 mol of toluene at $32^{\circ} \mathrm{C}$ . Pure toluene has a vapor pressure of 41 torr at $32^{\circ} \mathrm{C}$ . (Assume ideal behavior).

Keenan M.

University of Miami

The boiling point of ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ is $78.5^{\circ} \mathrm{C} .$ What is the boiling point of a solution of 6.4 $\mathrm{g}$ of vanillin $(\mathscr{M}=$

152.14 $\mathrm{g} / \mathrm{mol}$ ) in 50.0 $\mathrm{g}$ of ethanol $\left(K_{\mathrm{b}} \text { of ethanol }=1.22^{\circ} \mathrm{C} / \mathrm{m}\right) ?$

Keenan M.

University of Miami

The freezing point of benzene is $5.5^{\circ} \mathrm{C}$ . What is the freezing point of a solution of 5.00 $\mathrm{g}$ of naphthalene $\left(\mathrm{C}_{10} \mathrm{H}_{8}\right)$ in 444 $\mathrm{g}$ of benzene $\left(K_{\mathrm{f}} \text { of benzene }=4.90^{\circ} \mathrm{C} / \mathrm{m}\right) ?$

Keenan M.

University of Miami

What is the minimum mass of ethylene glycol $\left(\mathrm{C}_{2} \mathrm{H}_{6} \mathrm{O}_{2}\right)$ that must be dissolved in 14.5 $\mathrm{kg}$ of water to prevent the solution

from freezing at $-12.0^{\circ} \mathrm{F} ?$ (Assume ideal behavior.)

Keenan M.

University of Miami

What is the minimum mass of glycerol $\left(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}_{3}\right)$ that must be dissolved in 11.0 mg of water to prevent the solution from freezing at $-15^{\circ} \mathrm{C} ?$ (Assume ideal behavior.)

Keenan M.

University of Miami

A small protein has a molar mass of $1.50 \times 10^{4}$ g/mol. What is the osmotic pressure exerted at $24.0^{\circ} \mathrm{C}$ by 25.0 $\mathrm{mL}$ of an aqueous solution that contains 37.5 $\mathrm{mg}$ of the protein?

Keenan M.

University of Miami

A 125-mL sample of an aqueous solution of the protein ovalbumin from chicken egg white contains 1.31 g of the dissolved protein and has an osmotic pressure of 4.32 torr at $25^{\circ} \mathrm{C}$ .

What is the molar mass of ovalbumin?

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Assuming ideal behavior, find the freezing point of a solution made by dissolving 13.2 g of ammonium phosphate in 45.0 g of water

Keenan M.

University of Miami

Assuming ideal behavior, find the boiling point of a solution made by dissolving 32.8 g of calcium nitrate in 108 g of water.

Keenan M.

University of Miami

Calculate the molality and van’t Hoff factor (i) for the following aqueous solutions:

a) $1.00 \mathrm{mass} \% \mathrm{NaCl},$ freezing point $=-0.593^{\circ} \mathrm{C}$

b) 0.500 mass $\% \mathrm{CH}_{3}$ COOH, freezing point $=-0.159^{\circ} \mathrm{C}$

Keenan M.

University of Miami

Calculate the molality and van’t Hoff factor (i) for the following aqueous solutions:

a) 0.500 mass $\% \mathrm{KCl}$ , freezing point $=-0.234^{\circ} \mathrm{C}$

b) 1.00 mass $\% \mathrm{H}_{2} \mathrm{SO}_{4},$ freezing point $=-0.423^{\circ} \mathrm{C}$

Keenan M.

University of Miami

In a study designed to prepare new gasoline-resistant coatings, a polymer chemist dissolves 6.053 g of poly(vinyl alcohol) in enough water to make 100.0 $\mathrm{mL}$ of solution. At $25^{\circ} \mathrm{C},$ the osmotic pressure of this solution is 0.272 $\mathrm{atm}$ . What is the molar

mass of the polymer sample?

Keenan M.

University of Miami

The U.S. Food and Drug Administration lists dichloromethane $\left(\mathrm{CH}_{2} \mathrm{Cl}_{2}\right)$ and carbon tetrachloride (CCl,) among the many cancer-causing chlorinated organic compounds. What are the partial pressures of these substances in the vapor above a solu-

tion of 1.60 $\mathrm{mol}$ of $\mathrm{CH}_{2} \mathrm{Cl}_{2}$ and 1.10 $\mathrm{mol}$ of $\mathrm{CCl}_{4}$ at $23.5^{\circ} \mathrm{C} ?$ The vapor pressures of pure $\mathrm{CH}_{2} \mathrm{Cl}_{2}$ and $\mathrm{CCl}_{4}$ at $23.5^{\circ} \mathrm{C}$ are 352 torr and 118 torr, respectively. (Assume ideal behavior.)

Keenan M.

University of Miami

Is the fluid inside a bacterial cell considered a solution, a colloid, or both? Explain.

Keenan M.

University of Miami

What type of colloid is each of the following?

(a) Milk (b) Fog (c) Shaving cream

Keenan M.

University of Miami

In a movie theater, you can see the beam of projected light. What phenomenon does this exemplify? Why does it occur?

Keenan M.

University of Miami

Why don’t soap micelles coagulate and form large globules? Is soap more effective in freshwater or in seawater? Why?

Keenan M.

University of Miami

The three aqueous ionic solutions below have total volumes of 25. mL for A, 50. mL for B, and 100. mL for C. If each sphere represents 0.010 mol of ions, calculate: (a) the total molarity of ions for each solution; (b) the highest molarity of solute; (c) the lowest molality of solute (assuming the solution densities are equal); (d) the highest osmotic pressure (assuming ideal behavior).

Keenan M.

University of Miami

An aqueous solution is $10 . \%$ glucose by mass $(d=$ 1.039 $\mathrm{g} / \mathrm{mL}$ at $20^{\circ} \mathrm{C}$ ). Calculate its freezing point, boiling point at $1 \mathrm{atm},$ and osmotic pressure.

Keenan M.

University of Miami

Because zinc has nearly the same atomic radius as copper $\left(d=8.95 \mathrm{g} / \mathrm{cm}^{3}\right),$ zinc atoms substitute for some copper atoms in the many types of brass. Calculate the density of the brass with

(a) 10.0 atom $\% \mathrm{Zn}$ and (b) 38.0 atom $\% \mathrm{Zn}$ .

Keenan M.

University of Miami

Gold occurs in seawater at an average concentration of $1.1 \times 10^{-2}$ ppb. How many liters of seawater must be processed to recover 1 troy ounce of gold, assuming 81.5$\%$ efficiency (d of

seawater $=1.025 \mathrm{g} / \mathrm{mL} ; 1$ troy ounce $=31.1 \mathrm{g} ) ?$

Keenan M.

University of Miami

Use atomic properties to explain why xenon is 11 times as soluble as helium in water at $0^{\circ} \mathrm{C}$ on a mole basis.

Keenan M.

University of Miami

Which of the following best represents a molecular-scale view of an ionic compound in aqueous solution? Explain.

Keenan M.

University of Miami

Four 0.50 m aqueous solutions are depicted below. Assume that the solutions behave ideally.

(a) Which has the highest boiling point?

(b) Which has the lowest freezing point?

(c) Can you determine which one has the highest osmotic pressure? Explain.

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Thermal pollution from industrial wastewater causes the temperature of river or lake water to increase, which can affect fish survival as the concentration of dissolved $O_{2}$ decreases. Use the following data to find the molarity of $\mathrm{O}_{2}$ at each temperature (assume the solution density is the same as water):

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Pyridine (right) is an essential portion of many biologically active compounds, such as nicotine and vitamin $\mathrm{B}_{6}$ . Like ammonia, it has a nitrogen with a lone pair, which makes it act as a weak base. Because it is miscible in a wide range of solvents, from water to benzene, pyridine is one of the most important bases and solvents in organic syntheses. Account for its solubility behavior in terms of intermolecular forces.

Keenan M.

University of Miami

A chemist is studying small organic compounds for their potential use as an antifreeze. When 0.243 g of a compound is dissolved in 25.0 $\mathrm{mL}$ of water, the freezing point of the solution

is $-0.201^{\circ} \mathrm{C} .$

(a) Calculate the molar mass of the compound (d of water $=$ 1.00 $\mathrm{g} / \mathrm{mL} )$

(b) Analysis shows that the compound is 53.31 mass $\% \mathrm{C}$ and 11.18 mass $\% \mathrm{H}$ , the remainder being $\mathrm{O}$ . Calculate the empirical and molecular formulas of the compound.

(c) Draw a Lewis structure for a compound with this formula that forms $\mathrm{H}$ bonds and another for one that does not.

Keenan M.

University of Miami

Air in a smoky bar contains $4.0 \times 10^{-6} \mathrm{mol} / \mathrm{L}$ of $\mathrm{CO}$ . What

mass of $\mathrm{CO}$ is inhaled by a bartender who respires at a rate of 11 $\mathrm{L} / \mathrm{min}$ during an 8.0 -h shift?

Keenan M.

University of Miami

Is 50$\%$ by mass of methanol dissolved in ethanol different from 50$\%$ by mass of ethanol dissolved in methanol? Explain.

Keenan M.

University of Miami

Three gaseous mixtures of $\mathrm{N}_{2}$ (blue), $\mathrm{Cl}_{2}$ green), and Ne (purple) are depicted below. (a) Which has the smallest mole fraction of $\mathrm{N}_{2} ?(\mathrm{b})$ Which have the same mole fraction of Ne? (c) Rank all three in order of increasing mole fraction of $\mathrm{Cl}_{2}$ .

Keenan M.

University of Miami

A water treatment plant needs to attain a fluoride concentration of $4.50 \times 10^{-5} M .(\text { a) What mass of NaF must be added to }$ 5000 . L of water in a blending tank? (b) What mass per day of

fluoride is ingested by a person who drinks 2.0 $\mathrm{L}$ of this water?

Keenan M.

University of Miami

Four U tubes each have distilled water in the right arm, a solution in the left arm, and a semipermeable membrane between arms. (a) If the solute is KCl, which solution is most concentrated? (b) If each solute is different but all the solutions have the same molarity, which contains the smallest number of dissolved ions?

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$\beta$ -Pinene $\left(\mathrm{C}_{10} \mathrm{H}_{16}\right)$ and $\alpha$ -terpineol $\left(\mathrm{C}_{10} \mathrm{H}_{18} \mathrm{O}\right)$ are used in cosmetics to provide a "fresh pine" scent. At 367 $\mathrm{K}$ , the pure substances have vapor pressures of 100.3 torr and 9.8 torr, respectively. What is the composition of the vapor (in terms of mole fractions) above a solution containing equal masses of these compounds at 367 K? (Assume ideal behavior.)

Keenan M.

University of Miami

A solution of 1.50 g of solute dissolved in 25.0 mL of $\mathrm{H}_{2} \mathrm{O}$ at $25^{\circ} \mathrm{C}$ has a boiling point of $100.45^{\circ} \mathrm{C}$ (a) What is the molar mass of the solute if it is a nonvolatile nonelectrolyte and the solution behaves ideally $\left(d \text { of } \mathrm{H}_{2} \mathrm{O} \text { at } 25^{\circ} \mathrm{C}=0.997 \mathrm{g} / \mathrm{mL}\right)$ ?

(b) Conductivity measurements show that the solute is ionic with general formula $\mathrm{AB}_{2}$ or $\mathrm{A}_{2} \mathrm{B}$ . What is the molar mass if the solution behaves ideally? (c) Analysis indicates an empirical formula of $\mathrm{CaN}_{2} \mathrm{O}_{6}$ . Explain the difference between the actual formula mass and that calculated from the boiling point elevation. (d) Find the van't Hoff factor (i) for this solution.

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A pharmaceutical preparation made with ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ is contaminated with methanol $\left(\mathrm{CH}_{3} \mathrm{OH}\right) .$ A sample of vapor above the liquid mixture contains a 97$/ 1 \mathrm{mass}$ ratio of

$\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$ to $\mathrm{CH}_{3} \mathrm{OH}$ . What is the mass ratio of these alcohols in the liquid? At the temperature of the liquid, the vapor pressure of $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}$ and $\mathrm{CH}_{3} \mathrm{OH}$ are 60.5 tor and 126.0 torr, respectively

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Water treatment plants commonly use chlorination to destroy bacteria. A byproduct is chloroform $\left(\mathrm{CHCl}_{3}\right),$ a suspected carcinogen, produced when HOCl, formed by reaction of $\mathrm{Cl}_{2}$ and water, reacts with dissolved organic matter. The United States, Canada, and the World Health Organization have set a limit of $100 . \mathrm{ppb}$ of $\mathrm{CHCl}_{3}$ in drinking water. Convert this concentration into molarity, molality, mole fraction, and mass percent.

Keenan M.

University of Miami

A saturated $\mathrm{Na}_{2} \mathrm{CO}_{3}$ solution is prepared, and a small excess of solid is

present (white pile in beaker). A seed crystal of $\mathrm{Na}_{2}^{14} \mathrm{CO}_{3}\left(^{14} \mathrm{C}\right.$ is a radioactive isotope of $^{12} \mathrm{C} )$ is added (small red piece), and

the radioactivity is measured over time. (a) Would you expect radioactivity in the solution? Explain. (b) Would you expect radioactivity in all the solid or just in the seed crystal? Explain.

Keenan M.

University of Miami

A biochemical engineer isolates a bacterial gene fragment and dissolves a 10.0-mg sample in enough water to make 30.0 mL of solution. The osmotic pressure of the solution is 0.340 torr at $25^{\circ} \mathrm{C}(\text { a) What is the molar mass of the gene fragment? (b) If the }$ solution density is 0.997 $\mathrm{g} / \mathrm{mL}$ , how large is the freezing point depression for this solution $\left(K_{\mathrm{f}} \text { of water }=1.86^{\circ} \mathrm{C} / \mathrm{m}\right) ?$

Keenan M.

University of Miami

A river is contaminated with 0.65 $\mathrm{mg} / \mathrm{L}$ of dichloroethylene $\left(\mathrm{C}_{2} \mathrm{H}_{2} \mathrm{Cl}_{2}\right) .$ What is the concentration (in ng/L) of dichloroethylene at $21^{\circ} \mathrm{C}$ in the air breathed by a person swimming in the river

$\left(k_{\mathrm{H}} \text { for } \mathrm{C}_{2} \mathrm{H}_{2} \mathrm{Cl}_{2} \text { in water is } 0.033 \mathrm{mol} / \mathrm{L} \cdot \mathrm{atm}\right) ?$

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At an air-water interface, fatty acids such as oleic acid lie in a one-molecule-thick layer (monolayer), with the heads in the water and the tails perpendicular in the air. When 2.50 mg of oleic acid is placed on a water surface, it forms a circular monolayer 38.6 $\mathrm{cm}$ in diameter. Find the surface area (in $\mathrm{cm}^{2} )$ occupied by one molecule (} of oleic acid = 283 g/mol).

Keenan M.

University of Miami

A simple device used for estimating the concentration of total dissolved solids in an aqueous solution works by measuring the electrical conductivity of the solution. The method assumes that equal concentrations of different solids give approximately the same conductivity, and that the conductivity is proportional to concentration. The table below gives some actual electrical conductivities (in arbitrary units) for solutions of selected solids at the indicated concentrations (in ppm by mass):

a) How reliable are these measurements for estimating concentrations of dissolved solids? (b) For what types of substances might this method have a large error? Why? (c) Based on this method, an aqueous $\mathrm{CaCl}_{2}$ solution has a conductivity of 14.0 units. Calculate its mole fraction and molality.

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Two beakers are placed in a closed container (left). One beaker contains water, the other a concentrated aqueous sugar solution. With time, the solution volume increases and the water volume decreases (right). Explain on the molecular level.

Keenan M.

University of Miami

The release of volatile organic compounds into the atmosphere is regulated to limit ozone formation. In a laboratory simulation, 5% of the ethanol in a liquid detergent is released. Thus, a “down-the-drain” factor of 0.05 is used to estimate ethanol emissions from the detergent. The $k_{\mathrm{H}}$ values for ethanol and 2 -butoxyethanol $\left(\mathrm{C}_{4} \mathrm{H}_{9} \mathrm{OCH}_{2} \mathrm{CH}_{2} \mathrm{OH}\right)$ are $5 \times 10^{-6} \mathrm{atm} \cdot \mathrm{m}^{3} / \mathrm{mol}$and $1.6 \times 10^{-6}$ atm $\cdot \mathrm{m}^{3} / \mathrm{mol}$ , respectively. (a) Estimate a "down- the-drain" factor for 2 -butoxyethanol in the detergent. (b) What is the $k_{\mathrm{H}}$ for ethanol in units of $\mathrm{L}$ atm/mol? (c) Is this value consistent with a value given as 0.64 Pa'm $^{3} / \mathrm{mol} ?$

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Although other solvents are available, dichloromethane $\left(\mathrm{CH}_{2} \mathrm{Cl}_{2}\right)$ is still often used to "decaffeinate" drinks because the solubility of caffeine in $\mathrm{CH}_{2} \mathrm{Cl}_{2}$ is 8.35 times that in water.

(a) A 100.0 -mL sample of cola containing 10.0 $\mathrm{mg}$ of caffeine is extracted with 60.0 $\mathrm{mL}$ of $\mathrm{CH}_{2} \mathrm{Cl}_{2}$ . What mass of caffeine remains in the aqueous phase?

(b) A second identical cola sample is extracted with two successive 30.0 -mL portions of ${CH}_{2} {Cl}_{2}$ . What mass of caffeine remains in the aqueous phase after each extraction?

(c) Which approach extracts more caffeine?

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Tartaric acid occurs in crystalline residues found in wine vats. It is used in baking powders and as an additive in foods. It contains 32.3$\%$ by mass carbon and 3.97$\%$ by mass hydrogen; the balance is oxygen. When 0.981 g of tartaric acid is dissolved in 11.23 $\mathrm{g}$ of water, the solution freezes at $-1.26^{\circ} \mathrm{C}$ . Find the empirical and molecular formulas of tartaric acid.

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Methanol $\left(\mathrm{CH}_{3} \mathrm{OH}\right)$ and ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ are miscible because the major intermolecular force for each is H bonding. In some methanol-ethanol solutions, the mole fraction of methanol is higher, but the mass percent of ethanol is higher. What is the range of mole fraction of methanol for these solutions?

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A solution of 5.0 $\mathrm{g}$ of benzoic acid $\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}\right)$ in 100.0 $\mathrm{g}$ of carbon tetrachloride has a boiling point of $77.5^{\circ} \mathrm{C}$

(a) Calculate the molar mass of benzoic acid in the solution.

(b) Suggest a reason for the difference between the molar mass based on the formula and that found in part (a).

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Derive a general equation that expresses the relationship between the molarity and the molality of a solution. Why are the numerical values of these two terms approximately equal for very dilute aqueous solutions?

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A florist prepares a solution of nitrogen-phosphorus fertilizer by dissolving 5.66 $\mathrm{g}$ of $\mathrm{NH}_{4} \mathrm{NO}_{3}$ and 4.42 $\mathrm{g}$ of $\left(\mathrm{NH}_{4}\right)_{3} \mathrm{PO}_{4}$ in enough water to make 20.0 $\mathrm{L}$ of solution. What are the molarities

of $\mathrm{NH}_{4}^{+}$ and of $\mathrm{PO}_{4}^{3-}$ in the solution?

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Suppose coal-fired power plants used water in scrubbers to remove $\mathrm{SO}_{2}$ from smokestack gases (see Chemical Connections, p. 273 ). (a) If the partial pressure of $\mathrm{SO}_{2}$ in the stack gases is $2.0 \times 10^{-3}$ atm, what is the solubility of $\mathrm{SO}_{2}$ in the scrubber liquid $\left(k_{\mathrm{H}} \text { for } \mathrm{SO}_{2} \text { in water is } 1.23 \mathrm{mol} / \mathrm{L} \cdot \mathrm{atm} \text { at } 200 . \mathrm{C}\right) ?(\mathrm{b})$ From your answer to part (a), why are basic solutions, such as limewater slurries $\left[\mathrm{Ca (\mathrm{OH})_{2}\right],$ used in scrubbers?

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Urea is a white crystalline solid used as a fertilizer, in the pharmaceutical industry, and in the manufacture of certain polymer resins. Analysis of urea reveals that, by mass, it is 20.1$\%$ . carbon, 6.7$\%$ hydrogen, 46.5$\%$ nitrogen, and the balance oxygen.

(a) Find the empirical formula of urea.

(b) $\mathrm{A} 5.0 \mathrm{g} / \mathrm{L}$ solution of urea in water has an osmotic pressure of

2.04 $\mathrm{atm}$ , measured at $25^{\circ} \mathrm{C}$ . What is the molar mass and molecular

formula of urea?

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The total concentration of dissolved particles in blood is 0.30 M. An intravenous (IV) solution must be isotonic with blood, which means it must have the same concentration

(a) To relieve dehydration, a patient is given $100 . \mathrm{mL} / \mathrm{h}$ of $\mathrm{IV}$

glucose $\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)$ for 2.5 $\mathrm{h}$ . What mass (g) of glucose did she receive? (b) If isotonic saline (NaCl) is used, what is the molarity of the solution? (c) If the patient is given 150. mL/h of IV saline for 1.5 h, how many grams of NaCl did she receive?

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Deviations from Raoult’s law lead to the formation of azeotropes, constant boiling mixtures that cannot be separated by distillation, making industrial separations difficult. For components A and B, there is a positive deviation if the A-B attraction is less than A-A and B-B attractions (A and B reject each other),

and a negative deviation if the A-B attraction is greater than A-A and B-B attractions. If the A-B attraction is nearly equal to the A-A and B-B attractions, the solution obeys Raoult’s law. Explain

whether the behavior of each pair will be nearly ideal, have a positive deviation, or a negative deviation:

(a) Benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ and methanol

(b) Water and ethyl acetate

(c) Hexane and heptane

(d) Methanol and water

(e) Water and hydrochloric acid

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Acrylic acid $\left(\mathrm{CH}_{2}=\mathrm{CHCOOH}\right)$ is a monomer used to make superabsorbent polymers and various compounds for paint and adhesive production. At 1 atm, it boils at $141.5^{\circ} \mathrm{C}$ but is prone to polymerization. Its vapor pressure at $25^{\circ} \mathrm{C}$ is 4.1 mbar. What pressure (in mmHg) is needed to distill the pure acid at $65^{\circ} \mathrm{C} ?$

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To effectively stop polymerization, certain inhibitors require the presence of a small amount of $\mathrm{O}_{2}$ . At equilibrium with 1 atm of air, the concentration of $\mathrm{O}_{2}$ dissolved in the monomer acrylic acid $\left(\mathrm{CH}_{2}=\mathrm{CHCOOH}\right)$ is $1.64 \times 10^{-3} M .$ (a) What is $k_{\mathrm{H}}(\mathrm{mol} / \mathrm{L} \cdot \mathrm{atm} \mathrm{m})$ for $\mathrm{O}_{2}$ in acrylic acid? (b) If 0.005 atm of $\mathrm{O}_{2}$ is sufficient to stop polymerization, what is the molarity of $\mathrm{O}_{2} ?$ (c) What is the mole fraction? (d) What is the concentration in ppm? (Pure acrylic acid is $14.6 M ; P_{\mathrm{O}_{2}}$ in air is 0.2095 $\mathrm{atm.}$ .

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Volatile organic solvents have been implicated in adverse health effects in industrial workers. Greener methods are phasing these solvents out. Rank the solvents in Table 13.6 (p. 544) in terms of increasing volatility.

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At ordinary temperatures, water is a poor solvent for organic substances. But at high pressure and above $200^{\circ} \mathrm{C}$ , water develops many properties of organic solvents. Find the minimum pressure needed to maintain water as a liquid at $200 .^{\circ} \mathrm{C}\left(\Delta H_{\mathrm{vap}}=\right.$ 40.7 $\mathrm{kJ} / \mathrm{mol}$ at $100^{\circ} \mathrm{C}$ and $1.00 \mathrm{atm} ;$ assume that this value remains constant with temperature).

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In ice-cream making, the ingredients are kept below $0.0^{\circ} \mathrm{C}$ n an ice-salt bath. (a) Assuming that NaCl dissolves completely and forms an ideal solution, what mass of it is needed to lower the melting point of 5.5 $\mathrm{kg}$ of ice to $-5.0^{\circ} \mathrm{C} ?(\mathrm{b})$ Given the same assumptions as in part (a), what mass of $\mathrm{CaCl}_{2}$ is needed?

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Perfluorocarbons (PFCs), hydrocarbons with all H atoms

replaced by F atoms, have very weak cohesive forces. One interesting consequence of this property is that a live mouse can breathe while submerged in $\mathrm{O}_{2}$ -saturated PFCs.

(a) At $298 \mathrm{K},$ perfluorohexane $\left(\mathrm{C}_{6} \mathrm{F}_{14}, \mathrm{M}=338 \mathrm{g} / \mathrm{mol} \text { and } d=\right.$ 1.674 $\mathrm{g} / \mathrm{mL}$ ) in equilibrium with $101,325 \mathrm{Pa}$ of $\mathrm{O}_{2}$ has a mole fraction of $\mathrm{O}_{2}$ of $4.28 \times 10^{-3} .$ What is $k_{\mathrm{H}}$ in mol/L $\cdot$ atm $?$

(b) According to one source, $k_{\mathrm{H}}$ for $\mathrm{O}_{2}$ in water at $25^{\circ} \mathrm{C}$ is 756.7 $\mathrm{L} \cdot \mathrm{atm} / \mathrm{mol}$ . What is the solubility of $\mathrm{O}_{2}$ in water at $25^{\circ} \mathrm{C}$ in ppm? (c) Rank the $k_{\mathrm{H}}$ values in descending order for $\mathrm{O}_{2}$ in water,

ethanol, $\mathrm{C}_{6} \mathrm{F}_{14},$ and $\mathrm{C}_{6} \mathrm{H}_{14} .$ Explain your ranking.

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The solubility of $\mathrm{N}_{2}$ in blood is a serious problem for divers breathing compressed air $\left(78 \% \mathrm{N}_{2} \text { by volume) at depths }\right.$ greater than 50 $\mathrm{ft.}$

(a) What is the molarity of $\mathrm{N}_{2}$ in blood at 1.00 $\mathrm{atm}$ ?

(b) What is the molarity of $\mathrm{N}_{2}$ in blood at a depth of 50. ft?

(c) Find the volume (in $\mathrm{mL} )$ of $\mathrm{N}_{2},$ measured at $25^{\circ} \mathrm{C}$ and 1.00 $\mathrm{atm}$ ,released per liter of blood when a diver at a depth of 50 . ft rises to

the surface $\left(k_{\mathrm{H}} \text { for } \mathrm{N}_{2} \text { in water at } 25^{\circ} \mathrm{C} \text { is } 7.0 \times 10^{-4} \mathrm{mol} / \mathrm{L} \cdot \text { atm and }\right.$ at $37^{\circ} \mathrm{C}$ is $6.2 \times 10^{-4} \mathrm{mol} / \mathrm{L} \cdot$ atm; assume $d$ of water is 1.00 $\mathrm{g} / \mathrm{mL}$ ).

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Figure 12.11 (p. 466) shows the phase changes of pure

water. Consider how the diagram would change if air were present at 1 atm and dissolved in the water.

(a) Would the three phases of water still attain equilibrium at some temperature? Explain.

(b) In principle, would that temperature be higher, lower, or the same as the triple point for pure water? Explain.

(c) Would ice sublime at a few degrees below the freezing point under this pressure? Explain.

(d) Would the liquid have the same vapor pressure as that shown in Figure 12.7$(\mathrm{p} .464)$ at 100 $\mathrm{C}$ ? At $120^{\circ} \mathrm{C} ?$

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$\mathrm{KNO}_{3}, \mathrm{KClO}_{3}, \mathrm{KCl},$ and $\mathrm{NaCl}$ are recrystallized as follows: Step 1. A saturated aqueous solution of the compound is prepared at $50^{\circ} \mathrm{C}$

Step $2 .$ The mixture is filtered to remove undissolved compound.

Step $3 .$ The filtrate is cooled to $0^{\circ} \mathrm{C}$ .

Step $4 .$ The crystals that form are filtered, dried, and weighed.

(a) Which compound has the highest percent recovery and which the lowest (see Figure 13.19, p. 534)?

(b) Starting with 100. g of each compound, how many grams of neach can be recovered?

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Eighty proof whiskey is 40$\%$ ethanol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ by volume. A man has 7.0 $\mathrm{L}$ of blood and drinks 28 $\mathrm{mL}$ of the whiskey,

of which 22$\%$ of the ethanol goes into his blood.

(a) What concentration (in g/mL) of ethanol is in his blood (d of ethanol = 0.789 g/mL)?

(b) What volume (in mL) of whiskey would raise his blood alcohol level to $8.0 \times 10^{-4}$ g/mL, the level at which a person is considered intoxicated?

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Soft drinks are canned under 4 atm of $\mathrm{CO}_{2}$ and release $\mathrm{CO}_{2}$ when opened.

(a) How many moles of $\mathrm{CO}_{2}$ are dissolved in a $355-\mathrm{mL}$ can of

soda before it is opened?

(b) After it has gone flat?

(c) What volume (in L) would the released $\mathrm{CO}_{2}$ occupy at 1.00 $\mathrm{atm}$ and $25^{\circ} \mathrm{C}\left(k_{\mathrm{H}} \text { for } \mathrm{CO}_{2} \text { at } 25^{\circ} \mathrm{C} \text { is } 3.3 \times 10^{-2} \mathrm{mol} / \mathrm{L} \cdot \mathrm{atm} ; P_{\mathrm{CO}_{2}} \text { in air }\right.$ is $4 \times 10^{-4}$ atm $) ?$

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Gaseous $\mathrm{O}_{2}$ in equilibrium with $\mathrm{O}_{2}$ dissolved in water at 283 $\mathrm{K}$ is depicted at right. (a) Which scene below represents the system at 298 $\mathrm{K} ?$ (b) Which scene represents the system when the pressure of $\mathrm{O}_{2}$ is increased by half?

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