Chapter 15

Complete the changes in concentrations for each of the following reactions: (a) \(\operatorname{AgI}(s) \longrightarrow \mathrm{Ag}^{+}(a q)+\mathrm{I}^{-}(a q)\) (b) \(\mathrm{CaCO}_{3}(s) \longrightarrow \mathrm{Ca}^{2+}(a q)+\mathrm{CO}_{3}^{2-}(a q)\) (c) \(\operatorname{Mg}(\mathrm{OH})_{2}(s) \longrightarrow \mathrm{Mg}^{2+}(a q)+2 \mathrm{OH}^{-}(a q)\) (d) \(\operatorname{Mg}_{3}\left(\mathrm{PO}_{4}\right)_{2}(s) \longrightarrow 3 \mathrm{Mg}^{2+}(a q)+2 \mathrm{PO}_{4}^{3-}(a q)\) (e) \(\operatorname{Ca}_{5}\left(\mathrm{PO}_{4}\right)_{3} \mathrm{OH}(s) \longrightarrow 5 \mathrm{Ca}^{2+}(a q)+3 \mathrm{PO}_{4}^{3-}(a q)+\mathrm{OH}^{-}(a q)\)

Complete the changes in concentrations for each of the following reactions: (a) \(\operatorname{BaSO}_{4}(s) \rightarrow \mathrm{Ba}^{2+}(a q)+\mathrm{SO}_{4}^{2-}(a q)\) (b) \(\mathrm{Ag}_{2} \mathrm{SO}_{4}(s) \longrightarrow 2 \mathrm{Ag}^{+}(a q)+\mathrm{SO}_{4}^{2-}(a q)\) (c) \(\mathrm{Al}(\mathrm{OH})_{3}(s) \longrightarrow \mathrm{Al}^{3+}(a q)+3 \mathrm{OH}^{-}(a q)\) (d) \(\operatorname{Pb}(\mathrm{OH}) \mathrm{Cl}(s) \longrightarrow \mathrm{Pb}^{2+}(a q)+\mathrm{OH}^{-}(a q)+\mathrm{Cl}^{-}(a q)\) (e) \(\operatorname{Ca}_{3}\left(\mathrm{AsO}_{4}\right)_{2}(s) \longrightarrow 3 \mathrm{Ca}^{2+}(a q)+2 \mathrm{AsO}_{4}^{3-}(a q)\)

Write the ionic equation for the dissolution and the \(K_{\mathrm{sp}}\) expression for each of the following slightly soluble ionic compounds: (a) \(\mathrm{LaF}_{3}\) (b) \(\mathrm{CaCO}_{3}\) (c) \(\mathrm{Ag}_{2} \mathrm{SO}_{4}\) (d) \(\mathrm{Pb}(\mathrm{OH})_{2}\)

The Handbook of Chemistry and Physics (http://openstaxcollege.org/l/16Handbook) gives solubilities of the following compounds in grams per \(100 \mathrm{mL}\) of water. Because these compounds are only slightly soluble, assume that the volume does not change on dissolution and calculate the solubility product for each. (a) \(\mathrm{BaSiF}_{6}, 0.026 \mathrm{g} / 100 \mathrm{mL}\) (contains \(\mathrm{SiF}_{6}^{2-}\) ions) (b) \(\operatorname{Ce}\left(\mathrm{IO}_{3}\right)_{4}, 1.5 \times 10^{-2} \mathrm{g} / 100 \mathrm{mL}\) (c) \(\mathrm{Gd}_{2}\left(\mathrm{SO}_{4}\right)_{3}, 3.98 \mathrm{g} / 100 \mathrm{mL}\) (d) \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{PtBr}_{6}, 0.59 \mathrm{g} / 100 \mathrm{mL}\) (contains \(\mathrm{PtBr}_{6}^{2-}\) ions)

The Handbook of Chemistry and Physics (http://openstaxcollege.org///16Handbook) gives solubilities of the following compounds in grams per \(100 \mathrm{mL}\) of water. Because these compounds are only slightly soluble, assume that the volume does not change on dissolution and calculate the solubility product for each. (a) \(\mathrm{BaSeO}_{4}, 0.0118 \mathrm{g} / 100 \mathrm{mL}\) (b) \(\mathrm{Ba}\left(\mathrm{BrO}_{3}\right)_{2} \cdot \mathrm{H}_{2} \mathrm{O}, 0.30 \mathrm{g} / 100 \mathrm{mL}\) (c) \(\mathrm{NH}_{4} \mathrm{MgAsO}_{4} \cdot 6 \mathrm{H}_{2} \mathrm{O}, 0.038 \mathrm{g} / 100 \mathrm{mL}\) (d) \(\mathrm{La}_{2}\left(\mathrm{MoO}_{4}\right)_{3}, 0.00179 \mathrm{g} / 100 \mathrm{mL}\)

Assuming that no equilibrium other than dissolution are involved, calculate the molar solubility of each of the following from its solubility product: (a) \(\mathrm{KHC}_{4} \mathrm{H}_{4} \mathrm{O}_{6}\) (b) \(\mathrm{PbI}_{2}\) (c) \(\mathrm{Ag}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\), a salt containing the \(\mathrm{Fe}(\mathrm{CN})_{4}^{-}\) ion (d) \(\mathrm{Hg}_{2} \mathrm{I}_{2}\)

Assuming that no equilibria other than dissolution are involved, calculate the molar solubility of each of the following from its solubility product: (a) \(\mathrm{Ag}_{2} \mathrm{SO}_{4}\) (b) \(\mathrm{PbBr}_{2}\) (c) AgI (d) \(\mathrm{CaC}_{2} \mathrm{O}_{4} \cdot \mathrm{H}_{2} \mathrm{O}\)

The following concentrations are found in mixtures of ions in equilibrium with slightly soluble solids. From the concentrations given, calculate \(K_{\mathrm{sp}}\) for each of the slightly soluble solids indicated: (a) \(\mathrm{TlCl}:\left[\mathrm{T} 1^{+}\right]=1.21 \times 10^{-2} \mathrm{M},\left[\mathrm{Cl}^{-}\right]=1.2 \times 10^{-2} \mathrm{M}\) (b) \(\operatorname{Ce}\left(\operatorname{IO}_{3}\right)_{4}:\left[\mathrm{Ce}^{4+}\right]=1.8 \times 10^{-4} M,\left[\mathrm{IO}_{3}^{-}\right]=2.6 \times 10^{-13} \mathrm{M}\) (c) \(\mathrm{Gd}_{2}\left(\mathrm{SO}_{4}\right)_{3}:\left[\mathrm{Gd}^{3+}\right]=0.132 \mathrm{M},\left[\mathrm{SO}_{4}^{2-}\right]=0.198 \mathrm{M}\) (d) \(\mathrm{Ag}_{2} \mathrm{SO}_{4}:\left[\mathrm{Ag}^{+}\right]=2.40 \times 10^{-2} \mathrm{M},\left[\mathrm{SO}_{4}^{2-}\right]=2.05 \times 10^{-2} \mathrm{M}\) (e) \(\mathrm{BaSO}_{4}:\left[\mathrm{Ba}^{2+}\right]=0.500 \mathrm{M},\left[\mathrm{SO}_{4}^{2-}\right]=4.6 \times 10^{-8} \mathrm{M}\)

Which of the following compounds precipitates from a solution that has the concentrations indicated? (See Appendix J for \(K_{\mathrm{sp}}\) values.) (a) \(\mathrm{KClO}_{4}:\left[\mathrm{K}^{+}\right]=0.01 \mathrm{M},\left[\mathrm{ClO}_{4}^{-}\right]=0.01 \mathrm{M}\) (b) \(\mathrm{K}_{2} \mathrm{Pt} \mathrm{Cl}_{6}:\left[\mathrm{K}^{+}\right]=0.01 M,\left[\mathrm{PtCl}_{6}^{2-}\right]=0.01 \mathrm{M}\) (c) \(\mathrm{PbI}_{2}:\left[\mathrm{Pb}^{2+}\right]=0.003 \mathrm{M},\left[\mathrm{I}^{-}\right]=1.3 \times 10^{-3} \mathrm{M}\) (d) \(\mathrm{Ag}_{2} \mathrm{S}:\left[\mathrm{Ag}^{+}\right]=1 \times 10^{-10} \mathrm{M},\left[\mathrm{S}^{2-}\right]=1 \times 10^{-13} \mathrm{M}\)

A volume of 0.800 L of \(a 2 \times 10^{-4}-M\) Ba \(\left(\mathrm{NO}_{3}\right)_{2}\) solution is added to 0.200 L of \(5 \times 10^{-4} M\) Li \(_{2}\) SO \(_{4}\). Does BaSO \(_{4}\) precipitate? Explain your answer.

A solution contains 1.0 \(\times 10^{-5}\) mol of KBr and 0.10 mol of KCl per liter. AgNO \(_{3}\) is gradually added to this solution. Which forms first, solid AgBr or solid AgCl?

A solution contains \(1.0 \times 10^{-2}\) mol of \(\mathrm{KI}\) and 0.10 mol of \(\mathrm{KCl}\) per liter. AgNO \(_{3}\) is gradually added to this solution. Which forms first, solid AgI or solid AgCl?

53\. Perform the following calculations involving concentrations of iodate ions: (a) The iodate ion concentration of a saturated solution of \(\mathrm{La}\left(\mathrm{IO}_{3}\right)_{3}\) was found to be \(3.1 \times 10^{-3} \mathrm{mol} / \mathrm{L}\). Find the \(K_{\mathrm{sp}}\). (b) Find the concentration of iodate ions in a saturated solution of \(\mathrm{Cu}\left(\mathrm{IO}_{3}\right)_{2}\left(K_{\mathrm{sp}}=7.4 \times 10^{-8}\right)\).

Calculate the molar solubility of AgBr in \(0.035 M \mathrm{NaBr}\left(K_{\mathrm{sp}}=5 \times 10^{-13}\right)\).

How many grams of Milk of Magnesia, Mg(OH) \(_{2}(s)\) (58.3 g/mol), would be soluble in 200 mL of water. \(K_{\mathrm{sp}}=\) \(7.1 \times 10^{-12} .\) Include the ionic reaction and the expression for \(K_{\mathrm{sp}}\) in your answer. \(\left(K_{\mathrm{w}}=1 \times 10^{-14}=\right.\) \(\left.\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]\left[\mathrm{OH}^{-}\right]\right)\)

The carbonate ion concentration is gradually increased in a solution containing divalent cations of magnesium, calcium, strontium, barium, and manganese. Which of the following carbonates will form first? Which of the following will form last? Explain. \(\begin{array}{ll}\text { (a) } \mathrm{MgCO}_{3} & K_{\mathrm{sp}}=3.5 \times 10^{-8}\end{array}\) (b) \(\mathrm{CaCO}_{3} \quad K_{\mathrm{sp}}=4.2 \times 10^{-7}\) (c) \(\operatorname{Sr} \mathrm{CO}_{3} \quad K_{\mathrm{sp}}=3.9 \times 10^{-9}\) \(\begin{array}{ll}\text { (d) } \mathrm{BaCO}_{3} & K_{\mathrm{sp}}=4.4 \times 10^{-5}\end{array}\) (e) \(\mathrm{MnCO}_{3} \quad K_{\mathrm{sp}}=5.1 \times 10^{-9}\)

Sometimes equilibria for complex ions are described in terms of dissociation constants, \(K_{\mathrm{d}}\). For the complex ion AIF \(_{6}^{3-}\) the dissociation reaction is: \(\mathrm{AlF}_{6}^{3-} \rightleftharpoons \mathrm{Al}^{3+}+6 \mathrm{F}^{-}\) and \(K_{\mathrm{d}}=\frac{\left[\mathrm{Al}^{3+}\right]\left[\mathrm{F}^{-}\right]^{6}}{\left[\mathrm{AlF}_{6}^{3-}\right]}=2 \times 10^{-24}\) Calculate the value of the formation constant, \(K_{\mathrm{f}}\), for \(\mathrm{AlF}_{6}^{3-}\).

We have seen an introductory definition of an acid: An acid is a compound that reacts with water and increases the amount of hydronium ion present. In the chapter on acids and bases, we saw two more definitions of acids: a compound that donates a proton (a hydrogen ion, \(\mathrm{H}^{+}\) ) to another compound is called a Bronsted-Lowry acid, and a Lewis acid is any species that can accept a pair of electrons. Explain why the introductory definition is a macroscopic definition, while the Bronsted-Lowry definition and the Lewis definition are microscopic definitions.

Write the Lewis structures of the reactants and product of each of the following equations, and identify the Lewis acid and the Lewis base in each: (a) \(\mathrm{CO}_{2}+\mathrm{OH}^{-} \longrightarrow \mathrm{HCO}_{3}^{-}\) (b) \(\mathrm{B}(\mathrm{OH})_{3}+\mathrm{OH}^{-} \longrightarrow \mathrm{B}(\mathrm{OH})_{4}^{-}\) (c) \(\mathrm{I}^{-}+\mathrm{I}_{2} \longrightarrow \mathrm{I}_{3}^{-}\) (d) \(\mathrm{AlCl}_{3}+\mathrm{Cl}^{-} \longrightarrow \mathrm{AlCl}_{4}^{-}\) (use Al-Cl single bonds) (e) \(\mathrm{O}^{2-}+\mathrm{SO}_{3} \longrightarrow \mathrm{SO}_{4}^{2-}\)

Write the Lewis structures of the reactants and product of each of the following equations, and identify the Lewis acid and the Lewis base in each: (a) \(\mathrm{CS}_{2}+\mathrm{SH}^{-} \longrightarrow \mathrm{HCS}_{3}^{-}\) (b) \(\mathrm{BF}_{3}+\mathrm{F}^{-} \longrightarrow \mathrm{BF}_{4}^{-}\) (c) \(\mathrm{I}^{-}+\mathrm{SnI}_{2} \longrightarrow \mathrm{SnI}_{3}^{-}\) (d) \(\mathrm{Al}(\mathrm{OH})_{3}+\mathrm{OH}^{-} \longrightarrow \mathrm{Al}(\mathrm{OH})_{4}^{-}\) (e) \(\mathrm{F}^{-}+\mathrm{SO}_{3} \longrightarrow \mathrm{SFO}_{3}^{-}\)

In dilute aqueous solution HF acts as a weak acid. However, pure liquid HF (boiling point \(=19.5^{\circ} \mathrm{C}\) ) is a strong acid. In liquid HF, HNO _ acts like a base and accepts protons. The acidity of liquid HF can be increased by adding one of several inorganic fluorides that are Lewis acids and accept \(F^{-}\) ion (for example, \(B F_{3}\) or \(S\) bF \(_{5}\) ). Write balanced chemical equations for the reaction of pure \(\mathrm{HNO}_{3}\) with pure \(\mathrm{HF}\) and of pure \(\mathrm{HF}\) with \(\mathrm{BF}_{3}\).

The simplest amino acid is glycine, \(\mathrm{H}_{2} \mathrm{NCH}_{2} \mathrm{CO}_{2} \mathrm{H}\). The common feature of amino acids is that they contain the functional groups: an amine group, - \(\mathrm{NH}_{2}\), and a carboxylic acid group, \(-\mathrm{CO}_{2} \mathrm{H}\). An amino acid can function as either an acid or a base. For glycine, the acid strength of the carboxyl group is about the same as that of acetic acid, \(\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H},\) and the base strength of the amino group is slightly greater than that of ammonia, \(\mathrm{NH}_{3}\). (a) Write the Lewis structures of the ions that form when glycine is dissolved in \(1 M \mathrm{HCl}\) and in \(1 \mathrm{M} \mathrm{KOH}\). (b) Write the Lewis structure of glycine when this amino acid is dissolved in water. (Hint: Consider the relative base strengths of the \(-\mathrm{NH}_{2}\) and \(-\mathrm{CO}_{2}^{-}\) groups.)

Boric acid, \(\mathrm{H}_{3} \mathrm{BO}_{3}\), is not a Bronsted-Lowry acid but a Lewis acid. (a) Write an equation for its reaction with water. (b) Predict the shape of the anion thus formed. (c) What is the hybridization on the boron consistent with the shape you have predicted?

A saturated solution of a slightly soluble electrolyte in contact with some of the solid electrolyte is said to be a system in equilibrium. Explain. Why is such a system called a heterogeneous equilibrium?

What is the molar solubility of BaSO \(_{4}\) in a \(0.250-M\) solution of \(\mathrm{NaHSO}_{4} ? K_{\mathrm{a}}\) for \(\mathrm{HSO}_{4}^{-}=1.2 \times 10^{-2}\).

Which of the following compounds, when dissolved in a 0.01-M solution of HClO_ has a solubility greater than in pure water: AgBr, BaFz, Ca_(PO \(_{4}\) ) \(2,\) ZnS, PbI \(_{2}\) ? Explain your answer.

What is the effect on the amount of solid \(\mathrm{Mg}(\mathrm{OH})_{2}\) that dissolves and the concentrations of \(\mathrm{Mg}^{2+}\) and \(\mathrm{OH}^{-}\) when each of the following are added to a mixture of solid \(\mathrm{Mg}(\mathrm{OH})_{2}\) and water at equilibrium? (a) \(\mathrm{MgCl}_{2}\) (b) KOH (c) \(\mathrm{HClO}_{4}\) (d) \(\mathrm{NaNO}_{3}\) (e) \(\mathrm{Mg}(\mathrm{OH})_{2}\)

What is the effect on the amount of CaHPO \(_{4}\) that dissolves and the concentrations of \(\mathrm{Ca}^{2+}\) and \(\mathrm{HPO}_{4}^{-}\) -when each of the following are added to a mixture of solid \(\mathrm{CaHPO}_{4}\) and water at equilibrium? (a) \(\mathrm{CaCl}_{2}\) (b) HCl (c) \(\mathrm{KClO}_{4}\) (d) \(\mathrm{NaOH}\) (e) \(\mathrm{CaHPO}_{4}\)