Chapter 8

Calculate the molarity of each of the following solutions: a. \(0.56 \mathrm{mol} \mathrm{BaCl}_{2}\) in \(100.0 \mathrm{mL}\) of solution b. \(0.200 \mathrm{mol} \mathrm{Na}_{2} \mathrm{CO}_{3}\) in \(200.0 \mathrm{mL}\) of solution c. \(0.325 \mathrm{mol} \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\) in \(250.0 \mathrm{mL}\) of solution d. \(1.48 \mathrm{mol} \mathrm{KNO}_{3}\) in \(250.0 \mathrm{mL}\) of solution

Calculate the molarity of each of the following solutions: a. 0.150 mol urea \(\left[\left(\mathrm{NH}_{2}\right)_{2} \mathrm{CO}\right]\) in \(250.0 \mathrm{mL}\) of solution b. \(1.46 \mathrm{mol} \mathrm{NH}_{4} \mathrm{CH}_{3} \mathrm{CO}_{2}\) in \(1.000 \mathrm{L}\) of solution c. 1.94 mol methanol \(\left(\mathrm{CH}_{3} \mathrm{OH}\right)\) in 5.000 L of solution d. 0.045 mol sucrose \(\left(\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11}\right)\) in \(50.0 \mathrm{mL}\) of solution

Calculate the molarity of \(\mathrm{Na}^{+}\) ions in each of the following solutions: a. \(0.29 M \mathrm{NaNO}_{3}\) b. \(0.33 \mathrm{g} \mathrm{NaCl}\) in \(25 \mathrm{mL}\) of solution c. \(0.88 M \mathrm{Na}_{2} \mathrm{SO}_{4}\) d. \(0.46 \mathrm{g} \mathrm{Na}_{3} \mathrm{PO}_{4}\) in \(100 \mathrm{mL}\) of solution

Calculate the molarity of each of the following solutions: a. \(31.76 \mathrm{g} \mathrm{LiClO}_{4}\) in \(475.0 \mathrm{mL}\) of solution b. \(6.37 \mathrm{g}\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}\) in \(250.0 \mathrm{mL}\) of solution c. \(2.97 \mathrm{g} \mathrm{KBr}\) in \(75.0 \mathrm{mL}\) of solution d. \(0.773 \mathrm{g} \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}\) in \(100.0 \mathrm{mL}\) of solution

How many grams of solute are needed to prepare each of the following solutions? a. \(1.000 \mathrm{L}\) of \(0.200 M \mathrm{NaCl}\) b. \(250.0 \mathrm{mL}\) of \(0.125 M \mathrm{CuSO}_{4}\) c. \(500.0 \mathrm{mL}\) of \(0.400 M \mathrm{CH}_{3} \mathrm{OH}\)

How many grams of solute are needed to prepare each of the following solutions? a. \(500.0 \mathrm{mL}\) of \(0.250 M \mathrm{KBr}\) b. \(25.0 \mathrm{mL}\) of \(0.200 M \mathrm{NaNO}_{3}\) c. \(100.0 \mathrm{mL}\) of \(0.375 M \mathrm{CH}_{3} \mathrm{OH}\)

Zinc, copper, lead, and mercury ions are toxic to Atlantic salmon at concentrations of \(6.42 \times 10^{2} \mathrm{m} M, 7.16 \times\) \(10^{-3} \mathrm{m} M, 0.965 \mathrm{m} M,\) and \(5.00 \times 10^{-2} \mathrm{m} M,\) respectively. What are the corresponding concentrations in milligrams per liter?

Calculate the number of moles of solute contained in the following volumes of aqueous solutions of four over-thecounter pharmaceuticals: a. \(0.250 \mathrm{~L}\) of \(0.076 \mathrm{M}\) acetaminophen (for pain relief) b. \(2.11 \mathrm{~L}\) of \(0.193 \mathrm{~m} M\) chromalyn sodium (for hay fever) c. \(0.0475 \mathrm{~L}\) of \(5.73 \mathrm{~m} M\) benzocaine (in cough syrup) d. \(14.6 \mathrm{~L}\) of \(27.4 \mathrm{~m} M\) Benadryl (antihistamine)

A sample of crude oil contains \(3.13 \mathrm{m} M\) naphthalene, \(12.0 \mathrm{mM}\) methylnaphthalene, \(23.8 \mathrm{mM}\) dimethylnaphthalene, and \(14.1 \mathrm{m} M\) trimethylnaphthalene. What is the total number of moles of all the naphthalene compounds in \(100.0 \mathrm{mL}\) of the oil?

Tap water in North America from groundwater sources contains an average of \(48 \mathrm{mg} / \mathrm{L} \mathrm{Ca}^{2+}\) ion. What is the molarity of calcium ion in this water?

The concentration of manganese in one brand of soluble plant fertilizer is \(0.05 \%\) by mass. If a \(20 \mathrm{g}\) sample of the fertilizer is dissolved in 2.0 L of solution, what is the molarity of dissolved Mn in the solution?

For which of the following compounds is it possible to make a \(1.0 M\) solution at \(0^{\circ} \mathrm{C} ?\) a. \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O},\) solubility \(=23.1 \mathrm{g} / 100 \mathrm{mL}\) b. \(A g N O_{3},\) solubility \(=122\) g/ 100 mL c. \(\mathrm{Fe}\left(\mathrm{NO}_{3}\right)_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O},\) solubility \(=113 \mathrm{g} / 100 \mathrm{mL}\) d. \(\mathrm{Ca}(\mathrm{OH})_{2}\), solubility \(=0.185 \mathrm{g} / 100 \mathrm{mL}\)

Gold in the Ocean About \(6 \times 10^{9} \mathrm{g}\) of gold is thought to be dissolved in the oceans of the world. If the total volume of the oceans is \(1.5 \times 10^{21} \mathrm{L},\) what is the average molarity of gold in seawater?

A typical adult body contains \(6.0 \mathrm{L}\) of blood. The hemoglobin content of blood is about \(15.5 \mathrm{g} /\) \(100.0 \mathrm{mL}\) of blood. The approximate molar mass of hemoglobin is \(64,500 \mathrm{g} / \mathrm{mol} .\) How many moles of hemoglobin are present in a typical adult?

Calculate the final concentrations of the following aqueous solutions after each has been diluted to a final volume of \(25.0 \mathrm{mL}:\) a. \(1.00 \mathrm{mL}\) of \(0.452 M \mathrm{Na}^{+}\) b. \(2.00 \mathrm{mL}\) of \(3.4 \mathrm{m} M \mathrm{LiCl}\) c. \(5.00 \mathrm{mL}\) of \(6.42 \times 10^{-2} \mathrm{m} M \mathrm{Zn}^{2+}\)

Chemists who analyze samples for dissolved trace elements may buy standard solutions that contain \(1.000 \mathrm{g} / \mathrm{L}\) concentrations of the elements. If a chemist needs to prepare \(0.500 \mathrm{L}\) of a working standard that has a concentration of \(5.00 \mathrm{mg} / \mathrm{L},\) what volume of the \(1.000 \mathrm{g} / \mathrm{L}\) standard is needed?

A puddle of coastal seawater, caught in a depression formed by some coastal rocks at high tide, begins to evaporate on a hot summer day as the tide goes out. If the volume of the puddle decreases to \(23 \%\) of its initial volume, what is the concentration of \(\mathrm{Na}^{+}\) after evaporation if it was \(0.449 \mathrm{M}\) initially?

A standard dose of an over-the-counter cough suppressant for adults is \(20.0 \mathrm{mL}\) A portion this size contains 35 mg of the active pharmaceutical ingredient (API). A pediatrician prescribes the drug for a 6 -year-old child, but the child may take only \(10.0 \mathrm{mL}\) at a time and receive a maximum of 4.00 mg of the API. What is the concentration in \(\mathrm{mg} / \mathrm{mL}\) of the adult-strength medication, and how many milliliters of it should be diluted to make \(100.0 \mathrm{mL}\) of child-strength cough syrup?

A solution of table salt is a good conductor of electricity, but a solution containing an equal molar concentration of table sugar is not. Why?

Why can scientists use conductivity to study the mixing of freshwater and seawater in estuaries?

What are present in solutions of electrolytes that are not present in solutions of nonelectrolytes?

The electrolyte in an electricity-generating device called a fuel cell consists of a mixture of \(\mathrm{Li}_{2} \mathrm{CO}_{3}\) and \(\mathrm{K}_{2} \mathrm{CO}_{3}\) heated to \(650^{\circ} \mathrm{C} .\) At this temperature these ionic solids melt. Explain how the mixture of molten carbonates can conduct electricity.

Rank the following solutions on the basis of their ability to conduct electricity, starting with the most conductive: (a) \(1.0 \mathrm{M} \mathrm{NaCl} ;\) (b) \(1.2 \mathrm{M} \mathrm{KCl} ;\) (c) \(1.0 \mathrm{M} \mathrm{Na}_{2} \mathrm{SO}_{4}\) (d) \(0.75 M\) LiCl.

Rank the conductivities of \(1 M\) aqueous solutions of each of the following solutes, starting with the most conductive: (a) acetic acid; (b) methanol; (c) sucrose (table sugar); (d) hydrochloric acid.

What is the molarity of \(\mathrm{Na}^{+}\) ions in a \(0.025 M\) aqueous solution of (a) \(\mathrm{NaBr} ;\) (b) \(\mathrm{Na}_{2} \mathrm{SO}_{4} ;\) (c) \(\mathrm{Na}_{3} \mathrm{PO}_{4} ?\)

What is the molarity of each ion in a \(0.035 M\) aqueous solution of (a) \(\mathrm{NH}_{4} \mathrm{Cl} ;\) (b) \(\mathrm{Li}_{2} \mathrm{SO}_{4} ;\) (c) \(\mathrm{MgBr}_{2} ?\)

What chemical property of an acid makes it an acid?

What is the difference between a strong acid and a weak acid?

Give the formulas of two strong acids and two weak acids.

Why is \(\mathrm{HSO}_{4}^{-}(a q)\) a weaker acid than \(\mathrm{H}_{2} \mathrm{SO}_{4} ?\)

What chemical property of a base makes it a base?

What is the difference between a strong base and a weak base?

Give the formulas of two strong bases and two weak bases.

Write the net ionic equation for the neutralization of a strong acid by a strong base.

For each of the following acid-base reactions, identify the acid and the base and then write the net ionic equation: a. \(\mathrm{H}_{2} \mathrm{SO}_{4}(a q)+\mathrm{Ca}(\mathrm{OH})_{2}(s) \rightarrow \mathrm{CaSO}_{4}(a q)+2 \mathrm{H}_{2} \mathrm{O}(\ell)\) b. \(\mathrm{PbCO}_{3}(s)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \rightarrow \mathrm{PbSO}_{4}(s)+\mathrm{CO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(\ell)\) c. \(\mathrm{Ca}(\mathrm{OH})_{2}(s)+2 \mathrm{CH}_{3} \mathrm{COOH}(a q) \rightarrow\) \(\mathrm{Ca}\left(\mathrm{CH}_{3} \mathrm{COO}\right)_{2}(a q)+2 \mathrm{H}_{2} \mathrm{O}(\ell)\)

Complete and balance each of the following neutralization reactions, name the products, and write the net ionic equations. a. \(\mathrm{HI}(a q)+\mathrm{LiOH}(a q) \rightarrow\) b. \(\mathrm{H}_{3} \mathrm{PO}_{4}(a q)+\mathrm{KOH}(a q) \rightarrow\) c. \(\mathrm{Al}(\mathrm{OH})_{3}(s)+\mathrm{CH}_{3} \mathrm{COOH}(a q) \rightarrow\) d. \(\mathrm{HNO}_{3}(a q)+\mathrm{Ba}(\mathrm{OH})_{2}(a q) \rightarrow\)

Write a balanced molecular equation and a net ionic equation for the following reactions: a. Solid magnesium hydroxide reacts with a solution of sulfuric acid. b. Solid magnesium carbonate reacts with a solution of hydrochloric acid. c. Ammonia gas reacts with hydrogen chloride gas.

Write a balanced molecular equation and a net ionic equation for the following reactions: a. Solid aluminum hydroxide reacts with a solution of hydrobromic acid. b. A solution of sulfuric acid reacts with solid sodium carbonate. c. A solution of calcium hydroxide reacts with a solution of nitric acid.

The use of lead(II) carbonate and lead(II) hydroxide as white pigments in paint was discontinued in the United States in 1978 because these compounds dissolved in the stomachs of young children who ingested paint chips. The \(\mathrm{Pb}^{2+}\) ions released when the compounds dissolve interfere with neurotransmissions in the brain, causing neurological disorders. Using net ionic equations, show why lead(II) carbonate and lead(II) hydroxide dissolve in acidic solutions.

Lawn Care Many homeowners treat their lawns with \(\mathrm{CaCO}_{3}(s)\) to reduce the acidity of the soil. Write a net ionic equation for the reaction of \(\mathrm{CaCO}_{3}(s)\) with a strong acid.

What is the difference between a saturated solution and a supersaturated solution?

Calcium nitrate is soluble, but calcium phosphate is not. Explain this difference in solubility

A precipitate may appear when two completely clear aqueous solutions are mixed. What circumstances are responsible for this event?

Is a saturated solution always a concentrated solution? Explain.

Honey is a concentrated solution of sugar molecules in water. Clear, viscous honey becomes cloudy after being stored for long periods. Explain how this transition illustrates supersaturation.

According to the solubility rules in Table \(8.4,\) which of the following compounds have limited solubility in water? (a) barium sulfate; (b) barium hydroxide; (c) lanthanum nitrate; (d) sodium acetate; (e) lead hydroxide; (f) calcium phosphate

Complete and balance the chemical equations for the precipitation reactions, if any, between the following pairs of reactants, and write the net ionic equations: a. \(\operatorname{Pb}\left(\mathrm{NO}_{3}\right)_{2}(a q)+\mathrm{Na}_{2} \mathrm{SO}_{4}(a q) \rightarrow\) b. \(\mathrm{NiCl}_{2}(a q)+\mathrm{NH}_{4} \mathrm{NO}_{3}(a q) \rightarrow\) c. \(\operatorname{Fe} C l_{2}(a q)+N a_{2} S(a q) \rightarrow\) d. \(\operatorname{MgSO}_{4}(a q)+\mathrm{BaCl}_{2}(a q) \rightarrow\)

Show, with appropriate net ionic reactions, how \(\mathrm{Cr}^{3+}\) and \(\mathrm{Cd}^{2+}\) can be removed from wastewater by treatment with solutions of sodium hydroxide.

The solubility of \(\mathrm{CaCl}_{2}\) in water at \(25^{\circ} \mathrm{C}\) is \(81.1 \mathrm{g} / 100 \mathrm{mL}\) at \(0^{\circ} \mathrm{C}\) its solubility decreases to \(59.5 \mathrm{g} / 100 \mathrm{mL} .\) Answer the following questions about an aqueous solution of \(26.4 \mathrm{g}\) of \(\mathrm{CaCl}_{2}\) in a volume of \(37.5 \mathrm{mL}\) a. At \(25^{\circ} \mathrm{C},\) is this a saturated solution? b. If the solution is cooled to \(0^{\circ} \mathrm{C},\) do you expect a precipitate to form? c. If the solution is slowly cooled to \(0^{\circ} \mathrm{C}\) and no precipitate forms, then what kind of solution is it?

Calculate the mass of \(\mathrm{Mg} \mathrm{CO}_{3}\) precipitated by mixing \(10.0 \mathrm{mL}\) of a \(0.200 M \mathrm{Na}_{2} \mathrm{CO}_{3}\) solution with \(5.00 \mathrm{mL}\) of \(0.0500 M \mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}\) solution.