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General Chemistry: Principles and Modern Applications

Ralph H. Petrucci, F. Geoffrey Herring, Jeffry D. Madura

Chapter 18

Solubility and Complex-Ion Equilibria - all with Video Answers

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Chapter Questions

00:22

Problem 1

Write $K_{\text {sp }}$ expressions for the following equilibria. For example, for the reaction $\mathrm{AgCl}(\mathrm{s}) \rightleftharpoons \mathrm{Ag}^{+}(\mathrm{aq})+$ $\mathrm{Cl}^{-}(\mathrm{aq}), K_{\mathrm{sp}}=\left[\mathrm{Ag}^{+}\right]\left[\mathrm{Cl}^{-}\right]$.
(a) $\mathrm{Ag}_{2} \mathrm{SO}_{4}(\mathrm{s}) \rightleftharpoons 2 \mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{SO}_{4}^{2-}(\mathrm{aq})$
(b) $\operatorname{Ra}\left(\mathrm{IO}_{3}\right)_{2}(\mathrm{s}) \rightleftharpoons \mathrm{Ra}^{2+}(\mathrm{aq})+2 \mathrm{IO}_{3}^{-}(\mathrm{aq})$
(c) $\mathrm{Ni}_{3}\left(\mathrm{PO}_{4}\right)_{2}(\mathrm{s}) \rightleftharpoons 3 \mathrm{Ni}^{2+}(\mathrm{aq})+2 \mathrm{PO}_{4}^{3-}(\mathrm{aq})$
(d) $\mathrm{PuO}_{2} \mathrm{CO}_{3}(\mathrm{s}) \rightleftharpoons \mathrm{PuO}_{2}^{2+}(\mathrm{aq})+\mathrm{CO}_{3}^{2-}(\mathrm{aq})$

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00:19

Problem 2

Write solubility equilibrium equations that are described by the following $K_{\mathrm{sp}}$ expressions. For example, $K_{\mathrm{sp}}=$ $\left[\mathrm{Ag}^{+}\right]\left[\mathrm{Cl}^{-}\right] \quad$ represents $\quad \mathrm{AgCl}(\mathrm{s}) \rightleftharpoons \mathrm{Ag}^{+}(\mathrm{aq})+$ $\mathrm{Cl}^{-}(\mathrm{aq})$.
(a) $K_{\mathrm{sp}}=\left[\mathrm{Fe}^{3+}\right]\left[\mathrm{OH}^{-}\right]^{3}$
(b) $K_{\mathrm{sp}}=\left[\mathrm{BiO}^{+}\right]\left[\mathrm{OH}^{-}\right]$
(c) $K_{\mathrm{sp}}=\left[\mathrm{Hg}_{2}^{2+}\right]\left[\mathrm{I}^{-}\right]^{2}$
(d) $K_{\mathrm{sp}}=\left[\mathrm{Pb}^{2+}\right]^{3}\left[\mathrm{AsO}_{4}^{3-}\right]^{2}$

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00:18

Problem 3

The following $K_{\mathrm{sp}}$ values are found in a handbook. Write the solubility product expression to which each one applies. For example, $K_{\mathrm{sp}}(\mathrm{AgCl})=\left[\mathrm{Ag}^{+}\right]\left[\mathrm{Cl}^{-}\right]=$ $1.8 \times 10^{-10}$.
(a) $K_{\mathrm{sp}}\left(\mathrm{Cr} \mathrm{F}_{3}\right)=6.6 \times 10^{-11}$
(b) $K_{\mathrm{sp}}\left[\mathrm{Au}_{2}\left(\mathrm{C}_{2} \mathrm{O}_{4}\right)_{3}\right]=1 \times 10^{-10}$
(c) $K_{\mathrm{sp}}\left[\mathrm{Cd}_{3}\left(\mathrm{PO}_{4}\right)_{2}\right]=2.1 \times 10^{-33}$
(d) $K_{\mathrm{sp}}\left(\mathrm{Sr} \mathrm{F}_{2}\right)=2.5 \times 10^{-9}$

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01:50

Problem 4

Calculate the aqueous solubility, in moles per liter, of each of the following.
(a) $\mathrm{BaCrO}_{4}, K_{\mathrm{sp}}=1.2 \times 10^{-10}$
(b) $\mathrm{PbBr}_{2}, K_{\mathrm{sp}}=4.0 \times 10^{-5}$
(c) $\mathrm{CeF}_{3}, K_{\mathrm{sp}}=8 \times 10^{-16}$
(d) $\operatorname{Mg}_{3}\left(\mathrm{AsO}_{4}\right)_{2}, K_{\mathrm{sp}}=2.1 \times 10^{-20}$

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01:41

Problem 5

Arrange the following solutes in order of increasing molar solubility in water: $\mathrm{AgCN},$ $\mathrm{AgIO}_{3},$ $\mathrm{AgI},$ $\mathrm{AgNO}_{2},$ $\mathrm{Ag}_{2} \mathrm{SO}_{4}.$ Explain your reasoning.

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00:20

Problem 6

Which of the following saturated aqueous solutions would have the highest $\left[\mathrm{Mg}^{2+}\right]$: (a) $\mathrm{MgCO}_{3} ;$ (b) $\mathrm{MgF}_{2};$ (c) $\mathrm{Mg}_{3}\left(\mathrm{PO}_{4}\right)_{2} ?$ Explain.

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01:27

Problem 7

Fluoridated drinking water contains about 1 part per million (ppm) of $\mathrm{F}^{-}$. Is $\mathrm{CaF}_{2}$ sufficiently soluble in water to be used as the source of fluoride ion for the fluoridation of drinking water? Explain. [Hint: Think of 1 ppm as signifying $1 \mathrm{g} \mathrm{F}^{-}$ per $10^{6} \mathrm{g}$ solution.

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00:33

Problem 8

In the qualitative cation analysis procedure, $\mathrm{Bi}^{3+}$ is detected by the appearance of a white precipitate of bismuthyl hydroxide, $\mathrm{BiOOH}(\mathrm{s})$:
$\mathrm{BiOOH}(\mathrm{s}) \rightleftharpoons \mathrm{BiO}^{+}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq})$
$K_{\mathrm{sp}}=4 \times 10^{-10}$
Calculate the $\mathrm{pH}$ of a saturated aqueous solution of $\mathrm{BiOOH}$.

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02:20

Problem 9

A solution is saturated with magnesium palmitate $\left[\mathrm{Mg}\left(\mathrm{C}_{16} \mathrm{H}_{31} \mathrm{O}_{2}\right)_{2}, \text { a component of bathtub ring }\right] \mathrm{at}$ $50^{\circ} \mathrm{C} .$ How many milligrams of magnesium palmitate will precipitate from $965 \mathrm{mL}$ of this solution when it is cooled to $25^{\circ} \mathrm{C} ?$ For $\mathrm{Mg}\left(\mathrm{C}_{16} \mathrm{H}_{31} \mathrm{O}_{2}\right)_{2},$ $K_{\mathrm{sp}}=4.8 \times 10^{-12}$ at $50^{\circ} \mathrm{C}$ and $3.3 \times 10^{-12}$ at $25^{\circ} \mathrm{C}$.

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01:38

Problem 10

A 725 mL sample of a saturated aqueous solution of calcium oxalate, $\mathrm{CaC}_{2} \mathrm{O}_{4},$ at $95^{\circ} \mathrm{C}$ is cooled to $13^{\circ} \mathrm{C}$. How many milligrams of calcium oxalate will precipitate? For $\mathrm{CaC}_{2} \mathrm{O}_{4}, K_{\mathrm{sp}}=1.2 \times 10^{-8}$ at $95^{\circ} \mathrm{C}$ and $2.7 \times 10^{-9}$ at $13^{\circ} \mathrm{C}$.

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02:21

Problem 11

A $25.00 \mathrm{mL}$ sample of a clear saturated solution of $\mathrm{PbI}_{2}$ requires $13.3 \mathrm{mL}$ of a certain $\mathrm{AgNO}_{3}($ aq) for its titration. What is the molarity of this $\mathrm{AgNO}_{3}($ aq)?
$\mathrm{I}^{-}\left(\operatorname{satd} \mathrm{PbI}_{2}\right)+\mathrm{Ag}^{+}\left(\mathrm{from} \mathrm{AgNO}_{3}\right) \longrightarrow \mathrm{AgI}(\mathrm{s})$

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00:23

Problem 12

A $250 \mathrm{mL}$ sample of saturated $\mathrm{CaC}_{2} \mathrm{O}_{4}(\mathrm{aq})$ requires $4.8 \mathrm{mL}$ of $0.00134 \mathrm{M} \mathrm{KMnO}_{4}(\mathrm{aq})$ for its titration in an acidic solution. What is the value of $K_{\mathrm{sp}}$ for $\mathrm{CaC}_{2} \mathrm{O}_{4}$ obtained with these data? In the titration reaction, $\mathrm{C}_{2} \mathrm{O}_{4}^{2-}$ is oxidized to $\mathrm{CO}_{2}$ and $\mathrm{MnO}_{4}^{-}$ is reduced to $\mathrm{Mn}^{2+}$.

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02:39

Problem 13

To precipitate as $\mathrm{Ag}_{2} \mathrm{S}(\mathrm{s}),$ all the $\mathrm{Ag}^{+}$ present in $338 \mathrm{mL}$ of a saturated solution of $\mathrm{AgBrO}_{3}$ requires $30.4 \mathrm{mL}$ of $\mathrm{H}_{2} \mathrm{S}(\mathrm{g})$ measured at $23^{\circ} \mathrm{C}$ and $748 \mathrm{mm} \mathrm{Hg} .$ What is $K_{\mathrm{sp}}$ for $\mathrm{AgBrO}_{3} ?$

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01:27

Problem 14

Excess $\mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{s})$ is shaken with water to produce a saturated solution. A 50.00 mL sample of the clear saturated solution is withdrawn and requires $10.7 \mathrm{mL}$ of $0.1032 \mathrm{M} \mathrm{HCl}$ for its titration. What is $K_{\mathrm{sp}}$ for $\mathrm{Ca}(\mathrm{OH})_{2} ?$

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01:37

Problem 15

Calculate the molar solubility of $\mathrm{Mg}(\mathrm{OH})_{2}$ $\left(K_{\mathrm{sp}}=1.8 \times 10^{-11}\right)$ in (a) pure water; (b) $0.0862 \mathrm{M}$ $\mathrm{MgCl}_{2} ;$ (c) $0.0355 \mathrm{M} \mathrm{KOH}(\mathrm{aq})$.

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00:22

Problem 16

How would you expect the presence of each of the following solutes to affect the molar solubility of $\mathrm{CaCO}_{3}$ in water: (a) $\mathrm{Na}_{2} \mathrm{CO}_{3} ;$ (b) $\mathrm{HCl} ;$ (c) $\mathrm{NaHSO}_{4}$ ? Explain.

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00:07

Problem 17

Describe the effects of the salts $\mathrm{KI}$ and $\mathrm{AgNO}_{3}$ on the solubility of AgI in water.

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00:52

Problem 18

Describe the effect of the salt $\mathrm{KNO}_{3}$ on the solubility of AgI in water, and explain why it is different from the effects noted in Exercise 17.

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01:28

Problem 19

A $0.150 \mathrm{M} \mathrm{Na}_{2} \mathrm{SO}_{4}$ solution that is saturated with $\mathrm{Ag}_{2} \mathrm{SO}_{4}$ has $\left[\mathrm{Ag}^{+}\right]=9.7 \times 10^{-3} \mathrm{M} .$ What is the value of $K_{\mathrm{sp}}$ for $\mathrm{Ag}_{2} \mathrm{SO}_{4}$ obtained with these data?

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01:25

Problem 20

If $100.0 \mathrm{mL}$ of $0.0025 \mathrm{M} \mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{aq})$ is saturated with
$\mathrm{CaSO}_{4},$ how many grams of $\mathrm{CaSO}_{4}$ would be present in the solution? [Hint: Does the usual simplifying assumption hold?]

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01:53

Problem 21

What $\left[\mathrm{Pb}^{2+}\right]$ should be maintained in $\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})$
to produce a solubility of $1.5 \times 10^{-4} \mathrm{mol} \mathrm{PbI}_{2} / \mathrm{L}$ when $\mathrm{PbI}_{2}(\mathrm{s})$ is added?

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02:36

Problem 22

What $\left[\mathrm{I}^{-}\right]$ should be maintained in $\mathrm{KI}(\mathrm{aq})$ to produce to produce a solubility of $1.5 \times 10^{-4} \mathrm{mol} \mathrm{PbI}_{2} / \mathrm{L}$ when $\mathrm{PbI}_{2}(\mathrm{s})$ is added?

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02:40

Problem 23

Can the solubility of $\mathrm{Ag}_{2} \mathrm{CrO}_{4}$ be lowered to $5.0 \times 10^{-8} \mathrm{mol} \mathrm{Ag}_{2} \mathrm{CrO}_{4} / \mathrm{L}$ by using $\mathrm{CrO}_{4}^{2-}$ as the common ion? by using Ag+? Explain.

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01:07

Problem 24

A handbook lists the $K_{\mathrm{sp}}$ values $1.1 \times 10^{-10}$ for $\mathrm{BaSO}_{4}$ and $5.1 \times 10^{-9}$ for $\mathrm{BaCO}_{3} .$ When saturated $\mathrm{BaSO}_{4}(\mathrm{aq})$ is also made with $0.50 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq}),$ a precipitate of $\mathrm{BaCO}_{3}(\mathrm{s})$ forms. How do you account for this fact, given that $\mathrm{BaCO}_{3}$ has a larger $K_{\mathrm{sp}}$ than does $\mathrm{BaSO}_{4} ?$

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00:31

Problem 25

A particular water sample that is saturated in $\mathrm{CaF}_{2}$ has a $\mathrm{Ca}^{2+}$ content of $115 \mathrm{ppm}$ (that is, $115 \mathrm{g} \mathrm{Ca}^{2+}$ per $\left.10^{6} \mathrm{g} \text { of water sample }\right) .$ What is the $\mathrm{F}^{-}$ ion content of the water in ppm?

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03:28

Problem 26

Assume that, to be visible to the unaided eye, a precipitate must weigh more than $1 \mathrm{mg}$. If you add $1.0 \mathrm{mL}$ of $1.0 \mathrm{M} \mathrm{NaCl}(\mathrm{aq})$ to $100.0 \mathrm{mL}$ of a clear saturated aqueous AgCl solution, will you be able to see $\mathrm{AgCl}(\mathrm{s})$ precipitated as a result of the common-ion effect? Explain.

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01:51

Problem 27

Will precipitation of $\mathrm{MgF}_{2}(\mathrm{s})$ occur if a $22.5 \mathrm{mg}$ sample of $\mathrm{MgCl}_{2} \cdot 6 \mathrm{H}_{2} \mathrm{O}$ is added to $325 \mathrm{mL}$ of $0.035 \mathrm{M} \mathrm{KF}$ ?

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01:53

Problem 28

Will $\mathrm{PbCl}_{2}(\mathrm{s})$ precipitate when $155 \mathrm{mL}$ of $0.016 \mathrm{M}$ $\mathrm{KCl}(\mathrm{aq})$ are added to $245 \mathrm{mL}$ of $0.175 \mathrm{M}$ $\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq}) ?$

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01:10

Problem 29

What is the minimum $\mathrm{pH}$ at which $\mathrm{Cd}(\mathrm{OH})_{2}(\mathrm{s})$ will precipitate from a solution that is $0.0055 \mathrm{M}$ in $\mathrm{Cd}^{2+}(\mathrm{aq}) ?$

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00:30

Problem 30

What is the minimum $\mathrm{pH}$ at which $\mathrm{Cr}(\mathrm{OH})_{3}(\mathrm{s})$ will precipitate from a solution that is $0.086 \mathrm{M}$ in $\mathrm{Cr}^{3+}(\mathrm{aq}) ?$

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01:34

Problem 31

Will precipitation occur in the following cases?
(a) $0.10 \mathrm{mg}$ NaCl is added to $1.0 \mathrm{L}$ of $0.10 \mathrm{M}$ $\mathrm{AgNO}_{3}(\mathrm{aq})$.
(b) One drop $(0.05 \mathrm{mL})$ of $0.10 \mathrm{M} \mathrm{KBr}$ is added to 250 mL of a saturated solution of AgCl.
(c) One drop $(0.05 \mathrm{mL})$ of $0.0150 \mathrm{M} \mathrm{NaOH}(\mathrm{aq})$ is added to $3.0 \mathrm{L}$ of a solution with $2.0 \mathrm{mg} \mathrm{Mg}^{2+}$ per liter.

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02:06

Problem 32

The electrolysis of $\mathrm{MgCl}_{2}(\mathrm{aq})$ can be represented as $\mathrm{Mg}^{2+}(\mathrm{aq})+2 \mathrm{Cl}^{-}(\mathrm{aq})+2 \mathrm{H}_{2} \mathrm{O}(1) \longrightarrow$ $\mathrm{Mg}^{2+}(\mathrm{aq})+2 \mathrm{OH}^{-}(\mathrm{aq})+\mathrm{H}_{2}(\mathrm{g})+\mathrm{Cl}_{2}(\mathrm{g})$
The electrolysis of a 315 mL sample of $0.185 \mathrm{M} \mathrm{MgCl}_{2}$ is continued until $0.652 \mathrm{L} \mathrm{H}_{2}(\mathrm{g})$ at $22^{\circ} \mathrm{C}$ and $752 \mathrm{mmHg}$ has been collected. Will $\mathrm{Mg}(\mathrm{OH})_{2}(\mathrm{s})$ precipitate when electrolysis is carried to this point? [Hint: Notice that $\left[\mathrm{Mg}^{2+}\right]$ remains constant throughout the electrolysis, but $\left.\left[\mathrm{OH}^{-}\right] \text {increases. }\right]$

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02:25

Problem 33

Determine whether $1.50 \mathrm{g} \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}$ (oxalic acid: $K_{\mathrm{a}_{1}}=$
$\left.5.2 \times 10^{-2}, K_{\mathrm{a}_{2}}=5.4 \times 10^{-5}\right)$ can be dissolved in $0.200 \mathrm{L}$ of $0.150 \mathrm{M} \mathrm{CaCl}_{2}$ without the formation of $\mathrm{CaC}_{2} \mathrm{O}_{4}(\mathrm{s})\left(K_{\mathrm{sp}}=1.3 \times 10^{-9}\right)$.

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01:00

Problem 34

If $100.0 \mathrm{mL}$ of a clear saturated solution of $\mathrm{Ag}_{2} \mathrm{SO}_{4}$ is added to $250.0 \mathrm{mL}$ of a clear saturated solution of $\mathrm{PbCrO}_{4},$ will any precipitate form? [Hint: Take into account the dilutions that occur. What are the possible precipitates?]

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02:35

Problem 35

When $200.0 \mathrm{mL}$ of $0.350 \mathrm{M} \mathrm{K}_{2} \mathrm{CrO}_{4}(\mathrm{aq})$ are added to 200.0 mL of 0.0100 M AgNO 3(aq), what percentage of the $\mathrm{Ag}^{+}$ is left unprecipitated?

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01:26

Problem 36

What percentage of the original $\mathrm{Ag}^{+}$ remains in solution when $175 \mathrm{mL} 0.0208 \mathrm{M} \mathrm{AgNO}_{3}$ is added to $250 \mathrm{mL} 0.0380 \mathrm{M} \mathrm{K}_{2} \mathrm{CrO}_{4} ?$

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01:47

Problem 37

If a constant $\left[\mathrm{Cl}^{-}\right]=0.100 \mathrm{M}$ is maintained in a solution in which the initial $\left[\mathrm{Pb}^{2+}\right]=0.065 \mathrm{M},$ what percentage of the $\mathrm{Pb}^{2+}$ will remain in solution after $\mathrm{PbCl}_{2}(\mathrm{s})$ precipitates? What $\left[\mathrm{Cl}^{-}\right]$ should be maintained to ensure that only $1.0 \%$ of the $\mathrm{Pb}^{2+}$ remains unprecipitated?

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01:12

Problem 38

The ancient Romans added calcium sulfate to wine to clarify it and to remove dissolved lead. What is the maximum $\left[\mathrm{Pb}^{2+}\right]$ that might be present in wine to which calcium sulfate has been added?

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02:05

Problem 39

Assume that the seawater sample described in Example $18-6$ contains approximately $440 \mathrm{g} \mathrm{Ca}^{2+}$ per metric ton $(1 \text { metric ton }=10^{3} \mathrm{kg} ;$ density of. seawater $=1.03 \mathrm{g} / \mathrm{mL}$ ).
(a) Should $\mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{s})$ precipitate from seawater under the stated conditions, that is, with $\left[\mathrm{OH}^{-}\right]=2.0 \times 10^{-3} \mathrm{M} ?$
(b) Is the separation of $\mathrm{Ca}^{2+}$ from $\mathrm{Mg}^{2+}$ in seawater feasible?

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01:30

Problem 40

Which one of the following solutions can be used to separate the cations in an aqueous solution in which $\left[\mathrm{Ba}^{2+}\right]=\left[\mathrm{Ca}^{2+}\right]=0.050 \mathrm{M}: 0.10 \mathrm{M} \mathrm{NaCl}(\mathrm{aq}), 0.05 \mathrm{M}$ $\mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{aq}),$ $0.001 \mathrm{M}$ $\mathrm{NaOH}(\mathrm{aq}),$ or $0.50 \mathrm{M}$ $\mathrm{Na}_{2} \mathrm{CO}_{3}(\text { aq }) ?$ Explain why.

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03:30

Problem 41

$\mathrm{KI}(\mathrm{aq})$ is slowly added to a solution with $\left[\mathrm{Pb}^{2+}\right]=$ $\left[\mathrm{Ag}^{+}\right]=0.10 \mathrm{M} .$ For $\mathrm{PbI}_{2}, K_{\mathrm{sp}}=7.1 \times 10^{-9} ;$ for $\mathrm{AgI},$ $K_{\mathrm{sp}}=8.5 \times 10^{-17}$.
(a) Which precipitate should form first, $\mathrm{PbI}_{2}$ or AgI?
(b) What $\left[\mathrm{I}^{-}\right]$ is required for the second cation to begin to precipitate?
(c) What concentration of the first cation to precipitate remains in solution at the point at which the second cation begins to precipitate?
(d) $\operatorname{Can} \mathrm{Pb}^{2+}(\mathrm{aq})$ and $\mathrm{Ag}^{+}($ aq) be effectively separated by fractional precipitation of their iodides?

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01:28

Problem 42

A solution is $0.010 \mathrm{M}$ in both $\mathrm{CrO}_{4}^{2-}$ and $\mathrm{SO}_{4}^{2-}$. To this solution, $0.50 \mathrm{M} \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}(\text { aq })$ is slowly added.
(a) Which anion will precipitate first from solution?
(b) What is $\left[\mathrm{Pb}^{2+}\right]$ at the point at which the second anion begins to precipitate?
(c) Are the two anions effectively separated by this fractional precipitation?

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01:39

Problem 43

An aqueous solution that $2.00 \mathrm{M}$ in $\mathrm{AgNO}_{3}$ is slowly added from a buret to an aqueous solution that is $0.0100 \mathrm{M}$ in $\mathrm{Cl}^{-}$ and $0.250 \mathrm{M}$ in $\mathrm{I}^{-}$.
(a) Which ion, $\mathrm{Cl}^{-}$ or $\mathrm{I}^{-}$, is the first to precipitate?
(b) When the second ion begins to precipitate, what is the remaining concentration of the first ion?
(c) Is the separation of $\mathrm{Cl}^{-}$ and $\mathrm{I}^{-}$ feasible by fractional precipitation in this solution?

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03:19

Problem 44

$\mathrm{AgNO}_{3}(\mathrm{aq})$ is slowly added to a solution that is $0.250 \mathrm{M}$ $\mathrm{NaCl}$ and also $0.0022 \mathrm{M} \mathrm{KBr}$.
(a) Which anion will precipitate first, $\mathrm{Cl}^{-}$ or $\mathrm{Br}^{-}$ ?
(b) What is $\left[\mathrm{Ag}^{+}\right]$ at the point at which the second anion begins to precipitate?
(c) Can the $\mathrm{Cl}^{-1}$ and $\mathrm{Br}^{-}$ be separated effectively by this fractional precipitation?

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01:25

Problem 45

Which of the following solids is (are) more soluble in an acidic solution than in pure water: $\mathrm{KCl}$, $\mathrm{MgCO}_{3}$, $\mathrm{FeS}, \mathrm{Ca}(\mathrm{OH})_{2,}$ or $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH} ?$ Explain.

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00:56

Problem 46

Which of the following solids is (are) more soluble in a basic solution than in pure water: $\mathrm{BaSO}_{4}, \mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}$, $\mathrm{Fe}(\mathrm{OH})_{3}, \mathrm{NaNO}_{3},$ or MnS? Explain.

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00:30

Problem 47

The solubility of $\mathrm{Mg}(\mathrm{OH})_{2}$ in a particular buffer solution is $0.65 \mathrm{g} / \mathrm{L} .$ What must be the $\mathrm{pH}$ of the buffer solution?

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04:06

Problem 48

To 0.350 L of $0.150 \mathrm{M} \mathrm{NH}_{3}$ is added $0.150 \mathrm{L}$ of $0.100 \mathrm{M}$
$\mathrm{MgCl}_{2} .$ How many grams of $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$ should be present to prevent precipitation of $\mathrm{Mg}(\mathrm{OH})_{2}(\mathrm{s}) ?$

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00:47

Problem 49

For the equilibrium $\mathrm{Al}(\mathrm{OH})_{3}(\mathrm{s}) \rightleftharpoons \mathrm{Al}^{3+}(\mathrm{aq})+3 \mathrm{OH}^{-}(\mathrm{aq})$
$K_{\mathrm{sp}}=1.3 \times 10^{-33}$
(a) What is the minimum $p H$ at which $\mathrm{Al}(\mathrm{OH})_{3}(\mathrm{s})$ will precipitate from a solution that is $0.075 \mathrm{M}$ in $\mathrm{Al}^{3+} ?$
(b) A solution has $\left[\mathrm{Al}^{3+}\right]=0.075 \mathrm{M}$ and $\left[\mathrm{CH}_{3} \mathrm{COOH}\right]=1.00 \mathrm{M} .$ What is the maximum quantity of $\mathrm{NaCH}_{3} \mathrm{COO}$ that can be added to $250.0 \mathrm{mL}$ of this solution before precipitation of $\mathrm{Al}(\mathrm{OH})_{3}(\mathrm{s})$ begins?

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01:18

Problem 50

Will the following precipitates form under the given conditions?
(a) $\mathrm{PbI}_{2}(\mathrm{s}),$ from a solution that is $1.05 \times 10^{-3} \mathrm{M} \mathrm{HI}$, $1.05 \times 10^{-3} \mathrm{M} \mathrm{NaI},$ and $1.1 \times 10^{-3} \mathrm{M} \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}$.
(b) $\operatorname{Mg}(\mathrm{OH})_{2}(\mathrm{s}),$ from $2.50 \mathrm{L}$ of $0.0150 \mathrm{M} \mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}$ to which is added 1 drop $(0.05 \mathrm{mL})$ of $6.00 \mathrm{M} \mathrm{NH}_{3}$.
(c) $\mathrm{Al}(\mathrm{OH})_{3}(\mathrm{s})$ from a solution that is $0.010 \mathrm{M}$ in $\mathrm{Al}^{3+}, 0.010 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH},$ and $0.010 \mathrm{M} \mathrm{NaCH}_{3} \mathrm{COO}$.

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01:11

Problem 51

$\mathrm{PbCl}_{2}(\mathrm{s})$ is considerably more soluble in $\mathrm{HCl}(\mathrm{aq})$ than in pure water, but its solubility in $\mathrm{HNO}_{3}(\mathrm{aq})$ is not much different from what it is in water. Explain this difference in behavior.

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01:27

Problem 52

Which of the following would be most effective, and which would be least effective, in reducing the concentration of the complex ion $\left[\mathrm{Zn}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+}$ in a solution: $\mathrm{HCl}, \mathrm{NH}_{3},$ or $\mathrm{NH}_{4} \mathrm{Cl} ?$ Explain your choices.

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00:18

Problem 53

In a solution that is $0.0500 \mathrm{M}$ in $\left[\mathrm{Cu}(\mathrm{CN})_{4}\right]^{3-}$ and $0.80 \mathrm{M}$
in free $\mathrm{CN}^{-}$, the concentration of $\mathrm{Cu}^{+}$ is $6.1 \times 10^{-32} \mathrm{M}$ Calculate $K_{\mathrm{f}}$ of $\left[\mathrm{Cu}(\mathrm{CN})_{4}\right]^{3-}$.
$\mathrm{Cu}^{+}(\mathrm{aq})+4 \mathrm{CN}^{-}(\mathrm{aq}) \rightleftharpoons\left[\mathrm{Cu}(\mathrm{CN})_{4}\right]^{3-}(\mathrm{aq}) \quad K_{\mathrm{f}}=?$

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01:26

Problem 54

Calculate $\left[\mathrm{Cu}^{2+}\right]$ in a $0.10 \mathrm{M} \mathrm{CuSO}_{4}($ aq) solution that is also $6.0 \mathrm{M}$ in free $\mathrm{NH}_{3}$.
$\mathrm{Cu}^{2+}(\mathrm{aq})+4 \mathrm{NH}_{3}(\mathrm{aq}) \rightleftharpoons\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+}(\mathrm{aq})$
$K_{\mathrm{f}}=1.1 \times 10^{13}$

Lottie Adams
Lottie Adams
Numerade Educator
01:24

Problem 55

Can the following ion concentrations be maintained in the same solution without a precipitate forming:
$\left[\left[\mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}\right]^{3-}\right]=0.048 \mathrm{M},\left[\mathrm{S}_{2} \mathrm{O}_{3}^{2-}\right]=0.76 \mathrm{M},$ and $\left[\mathrm{I}^{-}\right]=2.0 \mathrm{M} ?$

Lottie Adams
Lottie Adams
Numerade Educator
03:16

Problem 56

A solution is $0.10 \mathrm{M}$ in free $\mathrm{NH}_{3}, 0.10 \mathrm{M}$ in $\mathrm{NH}_{4} \mathrm{Cl}$, and
$0.015 \mathrm{M}$ in $\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+} .$ Will $\mathrm{Cu}(\mathrm{OH})_{2}(\mathrm{s})$ precipitate from this solution? $K_{\mathrm{sp}}$ of $\mathrm{Cu}(\mathrm{OH})_{2}$ is $2.2 \times 10^{-20}$.

Lottie Adams
Lottie Adams
Numerade Educator
02:18

Problem 57

A 0.10 mol sample of $\mathrm{AgNO}_{3}(\mathrm{s})$ is dissolved in $1.00 \mathrm{L}$ of $1.00 \mathrm{M} \mathrm{NH}_{3} .$ How many grams of $\mathrm{KI}$ can be dissolved in this solution without a precipitate of $\mathrm{AgI}(\mathrm{s})$ forming?

Lottie Adams
Lottie Adams
Numerade Educator
02:55

Problem 58

A solution is prepared that has $\left[\mathrm{NH}_{3}\right]=1.00 \mathrm{M}$ and $\left[\mathrm{Cl}^{-}\right]=0.100 \mathrm{M} .$ How many grams of $\mathrm{AgNO}_{3}$ can be dissolved in 1.00 L of this solution without a precipitate of $\mathrm{AgCl}(\mathrm{s})$ forming?

Lottie Adams
Lottie Adams
Numerade Educator
03:35

Problem 59

Can $\mathrm{Fe}^{2+}$ and $\mathrm{Mn}^{2+}$ be separated by precipitating $\mathrm{FeS}(\mathrm{s})$ and not $\mathrm{MnS}(\mathrm{s}) ?$ Assume $\left[\mathrm{Fe}^{2+}\right]=\left[\mathrm{Mn}^{2+}\right]=$ $\left[\mathrm{H}_{2} \mathrm{S}\right]=0.10 \mathrm{M} .$ Choose a $\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]$ that ensures maximum precipitation of $\mathrm{FeS}(\mathrm{s})$ but not $\mathrm{MnS}(\mathrm{s}) .$ Will the separation be complete? For $\mathrm{FeS}, K_{\mathrm{spa}}=6 \times 10^{2} ;$ for $\mathrm{MnS}, K_{\mathrm{spa}}=3 \times 10^{7}$.

Arun Bana
Arun Bana
Numerade Educator
03:22

Problem 60

A solution is $0.05 \mathrm{M}$ in $\mathrm{Cu}^{2+},$ in $\mathrm{Hg}^{2+},$ and in $\mathrm{Mn}^{2+}$. Which sulfides will precipitate if the solution is made to be $0.10 \mathrm{M} \mathrm{H}_{2} \mathrm{S}(\mathrm{aq})$ and $0.010 \mathrm{M} \mathrm{HCl}(\mathrm{aq}) ?$ For $\mathrm{CuS}$, $K_{\mathrm{spa}}=6 \times 10^{-16} ;$ for $\mathrm{HgS}, K_{\mathrm{spa}}=2 \times 10^{-32} ;$ for $\mathrm{MnS}$, $K_{\mathrm{spa}}=3 \times 10^{7}$.

Lottie Adams
Lottie Adams
Numerade Educator
03:30

Problem 61

A buffer solution is $0.25 \mathrm{M}$ CH $_{3} \mathrm{COOH}-0.15 \mathrm{M}$ $\mathrm{NaCH}_{3} \mathrm{COO},$ saturated in $\mathrm{H}_{2} \mathrm{S}(0.10 \mathrm{M}),$ and with $\left[\mathrm{Mn}^{2+}\right]=0.15 \mathrm{M}$.
(a) Show that MnS will not precipitate from this solution (for $\left.\mathrm{MnS}, K_{\mathrm{spa}}=3 \times 10^{7}\right)$.
(b) Which buffer component would you increase in concentration, and to what minimum value, to ensure that precipitation of MnS(s) begins? Assume that the concentration of the other buffer component is held constant. [Hint: Recall equation (18.8).]

Lottie Adams
Lottie Adams
Numerade Educator
01:54

Problem 62

The following expressions pertain to the precipitation or dissolving of metal sulfides. Use information about the qualitative cation analysis scheme to predict whether a reaction proceeds to a significant extent in the forward direction and what the products are in each case.
(a) $\mathrm{Cu}^{2+}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{S}(\text { satd aq }) \longrightarrow$
(b) $\mathrm{Mg}^{2+}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{S}(\text { satd aq }) \stackrel{0.3 \mathrm{M} \mathrm{HCl}}{\longrightarrow}$
(c) $\operatorname{PbS}(\mathrm{s})+\mathrm{HCl}(0.3 \mathrm{M}) \longrightarrow$
(d) $\mathrm{ZnS}(\mathrm{s})+\mathrm{HNO}_{3}(\mathrm{aq}) \longrightarrow$

Lottie Adams
Lottie Adams
Numerade Educator
06:30

Problem 63

Suppose you did a group 1 qualitative cation analysis and treated the chloride precipitate with $\mathrm{NH}_{3}(\mathrm{aq})$ without first treating it with hot water. What might you observe, and what valid conclusions could you reach about cations present, cations absent, and cations in doubt?

Prashant Bana
Prashant Bana
Numerade Educator
03:59

Problem 64

Show that in qualitative cation analysis group $1,$ if you obtain $1.00 \mathrm{mL}$ of saturated $\mathrm{PbCl}_{2}(\mathrm{aq})$ at $25^{\circ} \mathrm{C}$, sufficient $\mathrm{Pb}^{2+}$ should be present to produce a precipitate of $\mathrm{PbCrO}_{4}(\mathrm{s}) .$ Assume that you use $1 \mathrm{drop}$ $(0.05 \mathrm{mL})$ of $1.0 \mathrm{M} \mathrm{K}_{2} \mathrm{CrO}_{4}$ for the test.

Prashant Bana
Prashant Bana
Numerade Educator
00:20

Problem 65

The addition of $\mathrm{HCl}(\mathrm{aq})$ to a solution containing several different cations produces a white precipitate. The filtrate is removed and treated with $\mathrm{H}_{2} \mathrm{S}(\mathrm{aq})$ in 0.3 M HCl. No precipitate forms. Which of the following conclusions is (are) valid? Explain.
(a) $\mathrm{Ag}^{+}$ or $\mathrm{Hg}_{2}^{2+}$ (or both) is probably present.
(b) $\mathrm{Mg}^{2+}$ is probably not present.
(c) $\mathrm{Pb}^{2+}$ is probably not present.
(d) $\mathrm{Fe}^{2+}$ is probably not present.

Shante Adams
Shante Adams
Numerade Educator
01:08

Problem 66

Write net ionic equations for the following qualitative cation analysis procedures.
(a) precipitation of $\mathrm{PbCl}_{2}(\mathrm{s})$ from a solution containing $\mathrm{Pb}^{2+}$
(b) dissolution of $\mathrm{Zn}(\mathrm{OH})_{2}(\mathrm{s})$ in a solution of $\mathrm{NaOH}(\mathrm{aq})$
(c) dissolution of $\mathrm{Fe}(\mathrm{OH})_{3}(\mathrm{s})$ in $\mathrm{HCl}(\mathrm{aq})$
(d) precipitation of $\mathrm{CuS}(\mathrm{s})$ from an acidic solution
of $\mathrm{Cu}^{2+}$ and $\mathrm{H}_{2} \mathrm{S}$

Lottie Adams
Lottie Adams
Numerade Educator
02:11

Problem 67

A particular water sample has 131 ppm of $\mathrm{CaSO}_{4}$ (131 $\mathrm{g} \mathrm{CaSO}_{4}$ per $10^{6} \mathrm{g}$ water). If this water is boiled in a teakettle, approximately what fraction of the water must be evaporated before $\mathrm{CaSO}_{4}(\mathrm{s})$ begins to precipitate? Assume that the solubility of $\mathrm{CaSO}_{4}(\mathrm{s})$ does not change much in the temperature range 0 to $100^{\circ} \mathrm{C}$.

Prashant Bana
Prashant Bana
Numerade Educator
02:22

Problem 68

A handbook lists the solubility of $\mathrm{CaHPO}_{4}$ as $0.32 \mathrm{g}$ $\mathrm{CaHPO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O} / \mathrm{L}$ and lists $K_{\mathrm{sp}}$ as $1 \times 10^{-7}$.
(a) Are these data consistent? (That is, are the molar solubilities the same when derived in two different ways?)
(b) If there is a discrepancy, how do you account for it?

Prashant Bana
Prashant Bana
Numerade Educator
01:52

Problem 69

A 50.0 mL sample of $0.0152 \mathrm{M} \mathrm{Na}_{2} \mathrm{SO}_{4}(\mathrm{aq})$ is added to
$50.0 \mathrm{mL}$ of $0.0125 \mathrm{M} \mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq}) .$ What percentage
of the $\mathrm{Ca}^{2+}$ remains unprecipitated?

Lottie Adams
Lottie Adams
Numerade Educator
03:06

Problem 70

What percentage of the $\mathrm{Ba}^{2+}$ in solution is precipitated as $\mathrm{BaCO}_{3}(\mathrm{s})$ if equal volumes of $0.0020 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}(\mathrm{aq})$ and $0.0010 \mathrm{M} \mathrm{BaCl}_{2}(\text { aq })$ are mixed?

Lottie Adams
Lottie Adams
Numerade Educator
01:44

Problem 71

Determine the molar solubility of lead(II) azide, $\mathrm{Pb}\left(\mathrm{N}_{3}\right)_{2},$ in a buffer solution with $\mathrm{pH}=3.00,$ given that
$\mathrm{Pb}\left(\mathrm{N}_{3}\right)_{2}(\mathrm{s}) \rightleftharpoons \mathrm{Pb}^{2+}(\mathrm{aq})+2 \mathrm{N}_{3}^{-}(\mathrm{aq})$
$K_{\mathrm{sp}}=2.5 \times 10^{-9}$
$\mathrm{HN}_{3}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(\mathrm{l}) \rightleftharpoons \mathrm{H}_{3} \mathrm{O}^{+}(\mathrm{aq})+\mathrm{N}_{3}^{-}(\mathrm{aq})$
$K_{\mathrm{a}}=1.9 \times 10^{-5}$

Lottie Adams
Lottie Adams
Numerade Educator
02:11

Problem 72

Calculate the molar solubility of $\mathrm{Mg}(\mathrm{OH})_{2}$ in $1.00 \mathrm{M}$ $\mathrm{NH}_{4} \mathrm{Cl}(\mathrm{aq})$.

Lottie Adams
Lottie Adams
Numerade Educator
02:05

Problem 73

The chief compound in marble is $\mathrm{CaCO}_{3}$. Marble has been widely used for statues and ornamental work on buildings. However, marble is readily attacked by acids. Determine the solubility of marble (that is, $\left.\left[\mathrm{Ca}^{2+}\right] \text { in a saturated solution }\right)$ in (a) normal rainwater of $\mathrm{pH}=5.6 ;$ (b) acid rainwater of $\mathrm{pH}=4.20 .$ Assume that the overall reaction that occurs is
$\mathrm{CaCO}_{3}(\mathrm{s})+\mathrm{H}_{3} \mathrm{O}^{+}(\mathrm{aq}) \rightleftharpoons$
$\mathrm{Ca}^{2+}(\mathrm{aq})+\mathrm{HCO}_{3}^{-}(\mathrm{aq})+\mathrm{H}_{2} \mathrm{O}(1)$

Lottie Adams
Lottie Adams
Numerade Educator
02:28

Problem 74

What is the solubility of $\mathrm{MnS}$, in grams per liter, in a buffer solution that is $0.100 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}-0.500 \mathrm{M}$ $\mathrm{NaCH}_{3} \mathrm{COO} ?$ For $\mathrm{MnS}, K_{\mathrm{spa}}=3 \times 10^{7}$.

Arun Bana
Arun Bana
Numerade Educator
01:05

Problem 75

Write net ionic equations for each of the following observations.
(a) When concentrated $\mathrm{CaCl}_{2}(\mathrm{aq})$ is added to $\mathrm{Na}_{2} \mathrm{HPO}_{4}(\mathrm{aq}),$ a white precipitate forms that is $38.7 \%$ Ca by mass.
(b) When a piece of dry ice, $\mathrm{CO}_{2}(\mathrm{s}),$ is placed in a clear dilute solution of limewater $\left[\mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{aq})\right]$, bubbles of gas evolve. At first, a white precipitate forms, but then it redissolves.

Lottie Adams
Lottie Adams
Numerade Educator
03:32

Problem 76

Concerning the reactions described in Exercise $75(\mathrm{b})$,
(a) Will the same observations be made if$\mathrm{Na}_{2} \mathrm{HPO}_{4}(\mathrm{aq}),$ a white precipitate forms that is $38.7 \%$ Ca by mass.
(b) When a piece of dry ice, $\mathrm{CO}_{2}(\mathrm{s}),$ is placed in a clear dilute solution of limewater $\left[\mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{aq})\right]$, bubbles of gas evolve. At first, a white precipitate forms, but then it redissolves.

Lottie Adams
Lottie Adams
Numerade Educator
02:34

Problem 77

Reaction (18.10), described in the Integrative Example, is called a carbonate transposition. In such a reaction, anions of a slightly soluble compound (for example, hydroxides and sulfates) are obtained in a sufficient concentration in aqueous solution that they can be identified by qualitative analysis tests. Suppose that $3 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}$ is used and that an anion concentration of $0.050 \mathrm{M}$ is sufficient for its detection. Predict whether carbonate transposition will be effective for detecting (a) $\mathrm{SO}_{4}^{2-}$ from $\mathrm{BaSO}_{4}(\mathrm{s}) ;$ (b) $\mathrm{Cl}^{-}$ from $\mathrm{AgCl}(\mathrm{s}) ;(\mathrm{c}) \mathrm{F}^{-}$ from $\mathrm{MgF}_{2}(\mathrm{s})$.

Rachel Vallejo
Rachel Vallejo
Numerade Educator
03:53

Problem 78

For the titration in Example $18-7,$ verify the assertion that $\left[\mathrm{Ag}^{+}\right]$ increases very rapidly between the point at which AgBr has finished precipitating and $\mathrm{Ag}_{2} \mathrm{CrO}_{4}$ is about to begin.

Bhumika Jayee
Bhumika Jayee
Numerade Educator
06:47

Problem 79

Aluminum compounds are soluble in acidic solution, where aluminum(III) exists as the complex ion $\left[\mathrm{Al}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+},$ which is generally represented simply as $\mathrm{Al}^{3+}(\mathrm{aq}) .$ They are also soluble in basic solutions, where the aluminum(III) is present as the complex ion $\left[\mathrm{Al}(\mathrm{OH})_{4}\right]^{-} .$ At certain intermediate $\mathrm{pH}$ values, the concentration of aluminum(III) that can exist in solution is at a minimum. Thus, a plot of the total concentration of aluminum(III) in solution as a function of $\mathrm{pH}$ yields a U-shaped curve. Demonstrate that this is the case with a few calculations.

Aadit Sharma
Aadit Sharma
Numerade Educator
02:17

Problem 80

The solubility of $\mathrm{AgCN}(\mathrm{s})$ in $0.200 \mathrm{M} \mathrm{NH}_{3}(\mathrm{aq})$ is $8.8 \times 10^{-6} \mathrm{mol} / \mathrm{L} .$ Calculate $K_{\mathrm{sp}}$ for $\mathrm{AgCN}$.

Lottie Adams
Lottie Adams
Numerade Educator
01:55

Problem 81

The solubility of $\mathrm{CdCO}_{3}(\mathrm{s})$ in $1.00 \mathrm{M} \mathrm{KI}(\mathrm{aq})$ is $1.2 \times 10^{-3} \mathrm{mol} / \mathrm{L} .$ Given that $K_{\mathrm{sp}}$ of $\mathrm{CdCO}_{3}$ is $5.2 \times 10^{-12},$ what is $K_{\mathrm{f}}$ for $\left[\mathrm{CdI}_{4}\right]^{2-} ?$

Lottie Adams
Lottie Adams
Numerade Educator
01:54

Problem 82

Use $K_{\mathrm{sp}}$ for $\mathrm{PbCl}_{2}$ and $K_{\mathrm{f}}$ for $\left[\mathrm{PbCl}_{3}\right]^{-}$ to determine the molar solubility of $\mathrm{PbCl}_{2}$ in $0.10 \mathrm{M} \mathrm{HCl}(\mathrm{aq}) .$ [Hint: What is the total concentration of lead species in solution?

Lottie Adams
Lottie Adams
Numerade Educator
02:11

Problem 83

A mixture of $\mathrm{PbSO}_{4}(\mathrm{s})$ and $\mathrm{PbS}_{2} \mathrm{O}_{3}(\mathrm{s})$ is shaken with
pure water until a saturated solution is formed. Both solids remain in excess. What is $\left[\mathrm{Pb}^{2+}\right]$ in the saturated solution? For $\mathrm{PbSO}_{4}, K_{\mathrm{sp}}=1.6 \times 10^{-8} ;$ for $\mathrm{PbS}_{2} \mathrm{O}_{3}, K_{\mathrm{sp}}=4.0 \times 10^{-7}$.

Arun Bana
Arun Bana
Numerade Educator
03:15

Problem 84

Use the method of Exercise 83 to determine $\left[\mathrm{Pb}^{2+}\right]$ in a saturated solution in contact with a mixture of $\mathrm{PbCl}_{2}(\mathrm{s})$ and $\mathrm{PbBr}_{2}(\mathrm{s})$.

Arun Bana
Arun Bana
Numerade Educator
View

Problem 85

A 2.50 g sample of $\mathrm{Ag}_{2} \mathrm{SO}_{4}(\mathrm{s})$ is added to a beaker containing 0.150 L of 0.025 M BaCl$_2$
(a) Write an equation for any reaction that occurs.
(b) Describe the final contents of the beaker- -that is, the masses of any precipitates present and the concentrations of the ions in solution.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:11

Problem 86

How many moles of solid sodium fluoride should be added to $1.0 \mathrm{L}$ of a saturated solution of barium fluoride, $\mathrm{BaF}_{2},$ at $25^{\circ} \mathrm{C}$ to raise the fluoride concentration to $0.030 \mathrm{mol} / \mathrm{L} ?$ What mass of $\mathrm{BaF}_{2}$ precipitates? You may ignore the hydrolysis of fluoride ion. [Hint: This first part of this problem is most easily solved by first writing down an electroneutrality condition. See pages $721-722 .]$

Yongyao Zhou
Yongyao Zhou
Numerade Educator
03:16

Problem 87

In an experiment to measure $K_{\mathrm{sp}}$ of $\mathrm{CaSO}_{4}$ [D. Masterman, J. Chem. Educ., 64, 409 (1987)], a saturated solution of $\mathrm{CaSO}_{4}(\mathrm{aq})$ is poured into the ion-exchange column pictured (and described in Chapter 21 ). As the solution passes through the column, $\mathrm{Ca}^{2+}$ is retained by the ion-exchange medium and $\mathrm{H}_{3} \mathrm{O}^{+}$ is released; two $\mathrm{H}_{3} \mathrm{O}^{+}$ ions appear in the effluent solution for every $\mathrm{Ca}^{2+}$ ion. As the drawing suggests, a $25.00 \mathrm{mL}$ sample is added to the column, and the effluent is collected and diluted to $100.0 \mathrm{mL}$ in a volumetric flask. A $10.00 \mathrm{mL}$ portion of the diluted solution requires $8.25 \mathrm{mL}$ of $0.0105 \mathrm{M} \mathrm{NaOH}$ for its titration. Use these data to obtain a value of $K_{\mathrm{sp}}$ for $\mathrm{CaSO}_{4}$.

Arun Bana
Arun Bana
Numerade Educator
02:05

Problem 88

In the Mohr titration, $\mathrm{Cl}^{-}(\mathrm{aq})$ is titrated with $\mathrm{AgNO}_{3}(\text { aq })$ in solutions that are at about $\mathrm{pH}=7$. Thus, it is suitable for determining the chloride ion content of drinking water. The indicator used in the titration is $\mathrm{K}_{2} \mathrm{CrO}_{4}(\text { aq }) .$ A red-brown precipitate of $\mathrm{Ag}_{2} \mathrm{CrO}_{4}(\mathrm{s})$ forms after all the $\mathrm{Cl}^{-}$ has precipitated. The titration reaction is $\mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq}) \longrightarrow \mathrm{AgCl}(\mathrm{s}) .$ At the
equivalence point of the titration, the titration mixture consists of $\mathrm{AgCl}(\mathrm{s})$ and a solution having neither $\mathrm{Ag}^{+}$ nor $\mathrm{Cl}^{-}$ in excess. Also, no $\mathrm{Ag}_{2} \mathrm{CrO}_{4}(\mathrm{s})$ is present, but it forms immediately after the equivalence point.
(a) How many milliliters of $0.01000 \mathrm{M} \mathrm{AgNO}_{3}(\mathrm{aq})$ are required to titrate $100.0 \mathrm{mL}$ of a municipal water sample having $29.5 \mathrm{mg} \mathrm{Cl}^{-} / \mathrm{L} ?$
(b) What is $\left[\mathrm{Ag}^{+}\right]$ at the equivalence point of the Mohr titration?
(c) What is $\left[\mathrm{CrO}_{4}^{2-}\right]$ in the titration mixture to meet the requirement of no precipitation of $\mathrm{Ag}_{2} \mathrm{CrO}_{4}(\mathrm{s})$ until immediately after the equivalence point?
(d) Describe the effect on the results of the titration if $\left[\mathrm{CrO}_{4}^{2-}\right]$ were (1) greater than that calculated in part (c) or (2) less than that calculated?
(e) Do you think the Mohr titration would work if the reactants were exchanged - that is, with $\mathrm{Cl}^{-}(\text {aq })$ as the titrant and $\mathrm{Ag}^{+}($ aq) in the sample being analyzed? Explain.

Lottie Adams
Lottie Adams
Numerade Educator
01:22

Problem 89

The accompanying drawing suggests a series of manipulations starting with saturated $\mathrm{Mg}(\mathrm{OH})_{2}(\mathrm{aq})$. Calculate $\left[\mathrm{Mg}^{2+}(\mathrm{aq})\right]$ at each of the lettered stages.
(a) $0.500 \mathrm{L}$ of saturated $\mathrm{Mg}(\mathrm{OH})_{2}(\mathrm{aq})$ is in contact with $\mathrm{Mg}(\mathrm{OH})_{2}(\mathrm{s})$.
(b) $0.500 \mathrm{L}$ of $\mathrm{H}_{2} \mathrm{O}$ is added to the $0.500 \mathrm{L}$ of solution in part (a), and the solution is vigorously stirred. Undissolved $\mathrm{Mg}(\mathrm{OH})_{2}(\mathrm{s})$ remains.
(c) $100.0 \mathrm{mL}$ of the clear solution in part (b) is removed and added to $0.500 \mathrm{L}$ of $0.100 \mathrm{M} \mathrm{HCl}(\mathrm{aq})$.
(d) $25.00 \mathrm{mL}$ of the clear solution in part (b) is removed and added to $250.0 \mathrm{mL}$ of $0.065 \mathrm{M} \mathrm{MgCl}_{2}(\mathrm{aq})$.
(e) $50.00 \mathrm{mL}$ of the clear solution in part (b) is removed and added to $150.0 \mathrm{mL}$ of $0.150 \mathrm{M} \mathrm{KOH}(\mathrm{aq})$.

Lottie Adams
Lottie Adams
Numerade Educator
00:55

Problem 90

In your own words, define the following terms or symbols: (a) $K_{\mathrm{sp}} ;$ (b) $K_{f} ;$ (c) $Q_{\mathrm{sp}} ;$ (d) complex ion.

Lottie Adams
Lottie Adams
Numerade Educator
00:58

Problem 91

Briefly describe each of the following ideas, methods, or phenomena: (a) common-ion effect in solubility equilibrium; (b) fractional precipitation; (c) ion-pair formation; (d) qualitative cation analysis.

Lottie Adams
Lottie Adams
Numerade Educator
01:03

Problem 92

Explain the important distinction between each pair of terms: (a) solubility and solubility product constant; (b) common-ion effect and salt effect; (c) ion pair and ion product.

Lottie Adams
Lottie Adams
Numerade Educator
00:53

Problem 93

Pure water is saturated with slightly soluble $\mathrm{PbI}_{2}$ Which of the following is a correct statement concerning the lead ion concentration in the solution, and what is wrong with the others? (a) $\left[\mathrm{Pb}^{2+}\right]=\left[\mathrm{I}^{-}\right]$; (b) $\left[\mathrm{Pb}^{2+}\right]=K_{\mathrm{sp}}$ of $\mathrm{PbI}_{2} ;(\mathrm{c})\left[\mathrm{Pb}^{2+}\right]=\sqrt{K_{\mathrm{sp}}}$ of $\mathrm{PbI}_{2}$; (d) $\left[\mathrm{Pb}^{2+}\right]=0.5\left[\mathrm{I}^{-}\right]$

Lottie Adams
Lottie Adams
Numerade Educator
00:11

Problem 94

Adding $1.85 \mathrm{g} \mathrm{Na}_{2} \mathrm{SO}_{4}$ to $500.0 \mathrm{mL}$ of saturated aqueous $\mathrm{BaSO}_{4}:$ (a) reduces $\left[\mathrm{Ba}^{2+}\right] ;$ (b) reduces $\left[\mathrm{SO}_{4}^{2-}\right]$; (c) increases the solubility of $\mathrm{BaSO}_{4} ;$ (d) has no effect.

Shante Adams
Shante Adams
Numerade Educator
00:25

Problem 95

The slightly soluble solute $\mathrm{Ag}_{2} \mathrm{CrO}_{4}$ is most soluble in (a) pure water; (b) $0.10 \mathrm{M} \mathrm{K}_{2} \mathrm{CrO}_{4} ;$ (c) $0.25 \mathrm{M} \mathrm{KNO}_{3}$; (d) $0.40 \mathrm{M} \mathrm{AgNO}_{3}$.

Lottie Adams
Lottie Adams
Numerade Educator
01:06

Problem 96

$\mathrm{Cu}^{2+}$ and $\mathrm{Pb}^{2+}$ are both present in an aqueous solution. To precipitate one of the ions and leave the other in solution, add (a) $\mathrm{H}_{2} \mathrm{S}(\mathrm{aq}) ;$ (b) $\mathrm{H}_{2} \mathrm{SO}_{4}(\mathrm{aq})$; (c) $\mathrm{HNO}_{3}(\mathrm{aq}) ;$ (d) $\mathrm{NH}_{4} \mathrm{NO}_{3}(\mathrm{aq})$.

Lottie Adams
Lottie Adams
Numerade Educator
00:38

Problem 97

All but two of the following solutions yield a precipitate when the solution is also made $2.00 \mathrm{M}$ in $\mathrm{NH}_{3}$.
Those two are (a) $\mathrm{MgCl}_{2}(\mathrm{aq}) ;$ (b) $\mathrm{FeCl}_{3}(\mathrm{aq})$; (c) $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}(\mathrm{aq}) ;(\mathrm{d}) \mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})$; (e) $\mathrm{Al}_{2}\left(\mathrm{SO}_{4}\right)_{3}(\mathrm{aq})$.

Lottie Adams
Lottie Adams
Numerade Educator
00:06

Problem 98

To increase the molar solubility of $\mathrm{CaCO}_{3}(\mathrm{s})$ in a saturated aqueous solution, add (a) ammonium chloride;
(b) sodium carbonate; (c) ammonia; (d) more water.

Shante Adams
Shante Adams
Numerade Educator
00:07

Problem 99

The best way to ensure complete precipitation from saturated $\mathrm{H}_{2} \mathrm{S}(\mathrm{aq})$ of a metal ion, $\mathrm{M}^{2+}$, as its sulfide, $\mathrm{MS}(\mathrm{s}),$ is to $(\mathrm{a})$ add an acid; $(\mathrm{b})$ increase $\left[\mathrm{H}_{2} \mathrm{S}\right]$ in the solution; (c) raise the $\mathrm{pH} ;$ (d) heat the solution.

Shante Adams
Shante Adams
Numerade Educator
02:32

Problem 100

Which of the following solids are likely to be more soluble in acidic solution and which in basic solution? Which are likely to have a solubility that is independent of pH? Explain. (a) $\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4} ;$ (b) $\mathrm{MgCO}_{3} ;$ (c) $\mathrm{CdS}$; (d) $\mathrm{KCl} ;$ (e) $\mathrm{NaNO}_{3} ;$ (f) $\mathrm{Ca}(\mathrm{OH})_{2}$.

Prashant Bana
Prashant Bana
Numerade Educator
00:47

Problem 101

Both $\mathrm{Mg}^{2+}$ and $\mathrm{Cu}^{2+}$ are present in the same aqueous solution. Which of the following reagents would work best in separating these ions, precipitating one and leaving the other in solution: $\mathrm{NaOH}(\mathrm{aq}), \mathrm{HCl}(\mathrm{aq})$, $\mathrm{NH}_{4} \mathrm{Cl}(\mathrm{aq}),$ or $\mathrm{NH}_{3}(\mathrm{aq}) ?$ Explain your choice.

Lottie Adams
Lottie Adams
Numerade Educator
05:00

Problem 102

Will $\mathrm{Al}(\mathrm{OH})_{3}(\mathrm{s})$ precipitate from a buffer solution that is $0.45 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}$ and $0.35 \mathrm{M} \mathrm{NaCH}_{3} \mathrm{COO}$ and also $0.275 \mathrm{M}$ in $\mathrm{Al}^{3+}(\mathrm{aq}) ?$ For $\mathrm{Al}(\mathrm{OH})_{3}, K_{\mathrm{sp}}=$
$1.3 \times 10^{-33} ;$ for $\mathrm{CH}_{3} \mathrm{COOH}, K_{\mathrm{a}}=1.8 \times 10^{-5}$.

Prashant Bana
Prashant Bana
Numerade Educator
00:08

Problem 103

Saturated solutions of sodium phosphate, copper(II) chloride, and ammonium acetate are mixed together. The precipitate is (a) copper(II) acetate; (b) copper(II) phosphate; (c) sodium chloride; (d) ammonium phosphate; (e) nothing precipitates.

Shante Adams
Shante Adams
Numerade Educator
03:47

Problem 104

Which of the following has the highest molar solubility? (a) $\mathrm{MgF}_{2}, K_{\mathrm{sp}}=3.7 \times 10^{-8}$
$\mathrm{MgCO}_{3}$, $K_{\mathrm{sp}}=3.5 \times 10^{-8} ;(\mathrm{c}) \mathrm{Mg}_{3}\left(\mathrm{PO}_{4}\right)_{2}, K_{\mathrm{sp}}=1 \times 10^{-25}$; (d) $\mathrm{Li}_{3} \mathrm{PO}_{4}, K_{\mathrm{sp}}=3.2 \times 10^{-9}$.

Aadit Sharma
Aadit Sharma
Numerade Educator
00:36

Problem 105

Lead(II) chloride is most soluble in (a) $0.100 \mathrm{M} \mathrm{NaCl}$; (b) $0.100 \mathrm{Na}_{2} \mathrm{S}_{2} \mathrm{O}_{3} ;(\mathrm{c}) 0.100 \mathrm{M} \mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2} ;(\mathrm{d}) 0.100 \mathrm{M}$
$\mathrm{NaNO}_{3} ;(\mathrm{e}) 0.100 \mathrm{MnSO}_{4}$.

Lottie Adams
Lottie Adams
Numerade Educator
00:35

Problem 106

Given the following ions in solution, $\mathrm{Hg}^{2+}, \mathrm{I}^{-}, \mathrm{Ag}^{+},$ and $\mathrm{NO}_{3}^{-}$, does the formation of a complex ion increase or decrease the amount of precipitate?

Lottie Adams
Lottie Adams
Numerade Educator
02:16

Problem 107

Will AgI(s) precipitate from a solution with $\left[\left[\mathrm{Ag}(\mathrm{CN})_{2}\right]^{-}\right]=0.012 \mathrm{M}, \left[\mathrm{CN}^{-}\right]=1.05 \mathrm{M}, $ and $\left[\mathrm{I}^{-}\right]=2.0 \mathrm{M} ?$ For $ \mathrm{AgI}, K_{\mathrm{sp}}=8.5 \times 10^{-17} ; =$ for $\left[\mathrm{Ag}(\mathrm{CN})_{2}\right]^{-}, K_{\mathrm{f}}=5.6 \times 10^{18}$.

Lottie Adams
Lottie Adams
Numerade Educator
01:04

Problem 108

Without performing detailed calculations, indicate whether either of the following compounds is appreciably soluble in $\mathrm{NH}_{3}(\mathrm{aq}):(\mathrm{a}) \mathrm{CuS}, K_{\mathrm{sp}}=6.3 \times 10^{-36},$(b) $\mathrm{CuCO}_{3}, K_{\mathrm{sp}}=1.4 \times 10^{-10} .$ Also use the fact that $K_{\mathrm{f}}$ for $\left[\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+}$ is $1.1 \times 10^{13}$.

Lottie Adams
Lottie Adams
Numerade Educator
04:33

Problem 109

Appendix E describes a useful study aid known as concept mapping. Using the methods presented in Appendix $\mathrm{E},$ construct a concept map that links the various factors affecting the solubility of slightly soluble solutes.

Prashant Bana
Prashant Bana
Numerade Educator