Chemistry & Chemical Reactivity

John C. Kotz, Paul M. Treichel, John Townsend, David Treichel

Chapter 17

Principles of Chemical Reactivity - all with Video Answers

Educators

Chapter Questions

Problem 1

Does the $\mathrm{pH}$ of the solution increase, decrease, or stay the same when you
(a) add solid ammonium chloride to a dilute aqueous solution of $\mathrm{NH}_3$ ?
(b) add solid sodium acetate to a dilute aqueous solution of acetic acid?
(c) add solid $\mathrm{NaCl}$ to a dilute aqueous solution of $\mathrm{NaOH}$ ?

CS

Connor Siggins

Numerade Educator

Problem 2

Does the $\mathrm{pH}$ of the solution increase, decrease, or stay the same when you
(a) add solid sodium oxalate, $\mathrm{Na}_2 \mathrm{C}_2 \mathrm{O}_4$, to $50.0 \mathrm{~mL}$ of $0.015 \mathrm{M}$ oxalic acid, $\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4$ ?
(b) add solid ammonium chloride to $75 \mathrm{~mL}$ of $0.016 \mathrm{M} \mathrm{HCl}$ ?
(c) add $20.0 \mathrm{~g}$ of $\mathrm{NaCl}$ to $1.0 \mathrm{~L}$ of $0.10 \mathrm{M}$ sodium acetate, $\mathrm{NaCH}_3 \mathrm{CO}_2$ ?

David Collins

Numerade Educator

Problem 3

What is the $\mathrm{pH}$ of a solution that consists of $0.20 \mathrm{M}$ ammonia, $\mathrm{NH}_3$, and $0.20 \mathrm{M}$ ammonium chloride, $\mathrm{NH}_4 \mathrm{Cl}$ ?

CS

Connor Siggins

Numerade Educator

Problem 4

What is the $\mathrm{pH}$ of a solution that consists of $0.25 \mathrm{M}$ formic acid, $\mathrm{HCO}_2 \mathrm{H}$, and $0.25 \mathrm{M}$ sodium formate, $\mathrm{NaHCO}_2$ ?

David Collins

Numerade Educator

Problem 5

What is the $\mathrm{pH}$ of $1.0 \mathrm{~L}$ of $0.20 \mathrm{M}$ acetic acid to which $16.4 \mathrm{~g}$ of sodium acetate, $\mathrm{NaCH}_3 \mathrm{CO}_2$, is added?

David Collins

Numerade Educator

Problem 6

What is the $\mathrm{pH}$ of $1.0 \mathrm{~L}$ of $0.30 \mathrm{M}$ ammonia to which $16.0 \mathrm{~g}$ of ammonium chloride, $\mathrm{NH}_4 \mathrm{Cl}$, is added?

Narayan Hari

Numerade Educator

Problem 7

What is the $\mathrm{pH}$ of the solution that results from adding $30.0 \mathrm{~mL}$ of $0.015 \mathrm{M} \mathrm{KOH}$ to $50.0 \mathrm{~mL}$ of $0.015 \mathrm{M}$ benzoic acid?

Yokshitha Reddy Bathula

Yokshitha Reddy Bathula

Numerade Educator

Problem 8

What is the $\mathrm{pH}$ of the solution that results from adding $25.0 \mathrm{~mL}$ of $0.12 \mathrm{M} \mathrm{HCl}$ to $25.0 \mathrm{~mL}$ of $0.43 \mathrm{M} \mathrm{NH}_3$ ?

David Collins

Numerade Educator

Problem 9

What is the $\mathrm{pH}$ of the buffer solution that contains $2.2 \mathrm{~g}$ of $\mathrm{NH}_4 \mathrm{Cl}$ in $250 \mathrm{~mL}$ of $0.12 \mathrm{M} \mathrm{NH}_3$ ? Is the final $\mathrm{pH}$ lower or higher than the $\mathrm{pH}$ of the $0.12 \mathrm{M}$ ammonia solution?

David Collins

Numerade Educator

Problem 10

Lactic acid $\left(\mathrm{CH}_3 \mathrm{CHOHCO} \mathrm{H}_2 \mathrm{H}\right)$ is found in sour milk, in sauerkraut, and in muscles after activity. $\left(K_{\mathrm{a}}\right.$ for lactic acid $=1.4 \times 10^{-4}$.)
(a) If $8.40 \mathrm{~g}$ of $\mathrm{NaCH}_3 \mathrm{CHOHCO}_2$, sodium lactate, is added to $5.00 \times 10^2 \mathrm{~mL}$ of $0.100 \mathrm{M}$ lactic acid, what is the $\mathrm{pH}$ of the resulting buffer solution?
(b) Is the $\mathrm{pH}$ of the buffered solution lower or higher than the $\mathrm{pH}$ of the lactic acid solution?

David Collins

Numerade Educator

Problem 11

What mass of sodium acetate, $\mathrm{NaCH}_3 \mathrm{CO}_2$, must be added to $1.00 \mathrm{~L}$ of $0.10 \mathrm{M}$ acetic acid to give a solution with a $\mathrm{pH}$ of 4.50 ?

Yokshitha Reddy Bathula

Yokshitha Reddy Bathula

Numerade Educator

Problem 12

What mass of ammonium chloride, $\mathrm{NH}_4 \mathrm{Cl}$, must be added to exactly $5.00 \times 10^2 \mathrm{~mL}$ of $0.10 \mathrm{M} \mathrm{NH}_3$ solution to give a solution with a $\mathrm{pH}$ of 9.50 ?

David Collins

Numerade Educator

Problem 13

Calculate the $\mathrm{pH}$ of a solution that has an acetic acid concentration of $0.050 \mathrm{M}$ and a sodium acetate concentration of $0.075 \mathrm{M}$.

David Collins

Numerade Educator

Problem 14

Calculate the $\mathrm{pH}$ of a solution that has an ammonium chloride concentration of $0.050 \mathrm{M}$ and an ammonia concentration of $0.045 \mathrm{M}$.

David Collins

Numerade Educator

Problem 15

What must the ratio of acetic acid to acetate ion be to have a buffer with a $\mathrm{pH}$ value of 4.50 ?

Aashna Calidas

Numerade Educator

Problem 16

What must the ratio of $\mathrm{H}_2 \mathrm{PO}_4^{-}$to $\mathrm{HPO}_4{ }^{2-}$ be to have a buffer with a $\mathrm{pH}$ value of 7.50 ?

David Collins

Numerade Educator

Problem 17

A buffer is composed of formic acid and its conjugate base, the formate ion.
(a) What is the $\mathrm{pH}$ of a solution that has a formic acid concentration of $0.050 \mathrm{M}$ and a sodium formate concentration of $0.035 \mathrm{M}$ ?
(b) What must the ratio of acid to conjugate base be to have a $\mathrm{pH}$ value 0.50 units higher than the value calculated in part (a)?

David Collins

Numerade Educator

Problem 18

A buffer solution is composed of $1.360 \mathrm{~g}$ of $\mathrm{KH}_2 \mathrm{PO}_4$ and $5.677 \mathrm{~g}$ of $\mathrm{Na}_2 \mathrm{HPO}_4$.
(a) What is the $\mathrm{pH}$ of the buffer solution?
(b) What mass of $\mathrm{KH}_2 \mathrm{PO}_4$ must be added to decrease the buffer solution $\mathrm{pH}$ by 0.50 unit from the value calculated in part (a)?

David Collins

Numerade Educator

Problem 19

Which of the following combinations would be the best to buffer the $\mathrm{pH}$ of a solution at approximately 5 ?
(a) $\mathrm{HCl}$ and $\mathrm{NaCl}$
(b) $\mathrm{NH}_3$ and $\mathrm{NH}_4 \mathrm{Cl}$
(c) $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}$ and $\mathrm{NaCH}_3 \mathrm{CO}_2$

CS

Connor Siggins

Numerade Educator

Problem 20

Which of the following combinations would be the best to buffer the $\mathrm{pH}$ of a solution at approximately 7 ?
(a) $\mathrm{H}_3 \mathrm{PO}_4$ and $\mathrm{NaH}_2 \mathrm{PO}_4$
(b) $\mathrm{NaH}_2 \mathrm{PO}_4$ and $\mathrm{Na}_2 \mathrm{HPO}_4$
(c) $\mathrm{Na}_2 \mathrm{HPO}_4$ and $\mathrm{Na}_3 \mathrm{PO}_4$

David Collins

Numerade Educator

Problem 21

Describe how to prepare a buffer solution from $\mathrm{NaH}_2 \mathrm{PO}_4$ and $\mathrm{Na}_2 \mathrm{HPO}_4$ to have a $\mathrm{pH}$ of 7.5 .

CS

Connor Siggins

Numerade Educator

Problem 22

Describe how to prepare a buffer solution from $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}$ and $\mathrm{NaCH}_3 \mathrm{CO}_2$ to have a $\mathrm{pH}$ of 4.5 .

Thomas Harr

Numerade Educator

Problem 23

Determine the volume (in $\mathrm{mL}$ ) of $1.00 \mathrm{M} \mathrm{NaOH}$ that must be added to $250 \mathrm{~mL}$ of $0.50 \mathrm{M}$ $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}$ to produce a buffer with a $\mathrm{pH}$ of 4.50 .

David Collins

Numerade Educator

Problem 24

Determine the volume (in $\mathrm{mL}$ ) of $1.00 \mathrm{M} \mathrm{HCl}$ that must be added to $750 \mathrm{~mL}$ of $0.50 \mathrm{M} \mathrm{HPO}_4{ }^{2-}$ to produce a buffer with a $\mathrm{pH}$ of 7.00 .

David Collins

Numerade Educator

Problem 25

A buffer solution was prepared by adding $4.95 \mathrm{~g}$ of sodium acetate, $\mathrm{NaCH}_3 \mathrm{CO}_2$, to $2.50 \times 10^2 \mathrm{~mL}$ of $0.150 \mathrm{M}$ acetic acid, $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}$.
(a) What is the $\mathrm{pH}$ of the buffer?
(b) What is the $\mathrm{pH}$ of $1.00 \times 10^2 \mathrm{~mL}$ of the buffer solution if you add $82 \mathrm{mg}$ of $\mathrm{NaOH}$ to the solution?

David Collins

Numerade Educator

Problem 26

You dissolve $0.425 \mathrm{~g}$ of $\mathrm{NaOH}$ in $2.00 \mathrm{~L}$ of a buffer solution that has $\left[\mathrm{H}_2 \mathrm{PO}_4{ }^{-}\right]=\left[\mathrm{HPO}_4{ }^{2-}\right]=0.132 \mathrm{M}$. What is the $\mathrm{pH}$ of the solution before adding $\mathrm{NaOH}$ ? After adding $\mathrm{NaOH}$ ?

David Collins

Numerade Educator

Problem 27

A buffer solution is prepared by adding $0.125 \mathrm{~mol}$ of ammonium chloride to $5.00 \times 10^2 \mathrm{~mL}$ of $0.500 \mathrm{M}$ solution of ammonia.
(a) What is the $\mathrm{pH}$ of the buffer?
(b) If $0.0100 \mathrm{~mol}$ of $\mathrm{HCl}$ gas is bubbled into $5.00 \times 10^2 \mathrm{~mL}$ of the buffer, what is the new $\mathrm{pH}$ of the solution?

David Collins

Numerade Educator

Problem 28

What is the $\mathrm{pH}$ change when $20.0 \mathrm{~mL}$ of $0.100 \mathrm{M}$ $\mathrm{NaOH}$ is added to $80.0 \mathrm{~mL}$ of a buffer solution consisting of $0.169 \mathrm{M} \mathrm{NH}_3$ and $0.183 \mathrm{M} \mathrm{NH}_4 \mathrm{Cl}$ ?

David Collins

Numerade Educator

Problem 29

A buffer consists of $0.50 \mathrm{~mol}$ of $\mathrm{NaH}_2 \mathrm{PO}_4$ and $0.50 \mathrm{~mol}$ of $\mathrm{Na}_2 \mathrm{HPO}_4$ diluted to a volume of $1.0 \mathrm{~L}$.
(a) What is the $\mathrm{pH}$ of the buffer?
(b) What volume of $0.15 \mathrm{M} \mathrm{NaOH}$ is required to raise the $\mathrm{pH}$ of the buffer by 1.00 ?

David Collins

Numerade Educator

Problem 30

A buffer consists of $0.36 \mathrm{~mol}$ of $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}$ and $0.36 \mathrm{~mol}$ of $\mathrm{NaCH}_3 \mathrm{CO}_2$ diluted to a volume of $1.0 \mathrm{~L}$.
(a) What is the $\mathrm{pH}$ of the buffer?
(b) What volume of $0.10 \mathrm{M} \mathrm{HCl}$ is required to decrease the $\mathrm{pH}$ of the buffer by 1.00 ?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 31

Phenol, $\mathrm{C}_6 \mathrm{H}_5 \mathrm{OH}$, is a weak organic acid. Suppose $0.515 \mathrm{~g}$ of the compound is dissolved in enough water to make $125 \mathrm{~mL}$ of solution. The resulting solution is titrated with $0.123 \mathrm{M} \mathrm{NaOH}$.
$$
\mathrm{C}_6 \mathrm{H}_5 \mathrm{OH}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq}) \rightleftarrows \mathrm{C}_6 \mathrm{H}_5 \mathrm{O}^{-}(\mathrm{aq})+\mathrm{H}_2 \mathrm{O}(\ell)
$$
(a) What is the $\mathrm{pH}$ of the original solution of phenol?
(b) What are the concentrations of all of the following ions at the equivalence point: $\mathrm{Na}^{+}$, $\mathrm{H}_3 \mathrm{O}^{+}, \mathrm{OH}^{-}$, and $\mathrm{C}_6 \mathrm{H}_5 \mathrm{O}^{-}$?
(c) What is the $\mathrm{pH}$ of the solution at the equivalence point?

David Collins

Numerade Educator

Problem 32

Assume you dissolve $0.235 \mathrm{~g}$ of the weak acid benzoic acid, $\mathrm{C}_6 \mathrm{H}_5 \mathrm{CO}_2 \mathrm{H}$, in enough water to make $1.00 \times 10^2 \mathrm{~mL}$ of solution and then titrate the solution with $0.108 \mathrm{M} \mathrm{NaOH}$.
$$
\begin{aligned}
& \mathrm{C}_6 \mathrm{H}_5 \mathrm{CO}_2 \mathrm{H}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq}) \rightleftharpoons \\
& \mathrm{C}_6 \mathrm{H}_5 \mathrm{CO}_2{ }^{-}(\mathrm{aq})+\mathrm{H}_2 \mathrm{O}(\ell) \\
&
\end{aligned}
$$
(a) What was the $\mathrm{pH}$ of the original benzoic acid solution?
(b) What are the concentrations of all of the following ions at the equivalence point: $\mathrm{Na}^{+}$, $\mathrm{H}_3 \mathrm{O}^{+}, \mathrm{OH}^{-}$, and $\mathrm{C}_6 \mathrm{H}_5 \mathrm{CO}_2^{-}$?
(c) What is the $\mathrm{pH}$ of the solution at the equivalence point?

David Collins

Numerade Educator

Problem 33

You require $36.78 \mathrm{~mL}$ of $0.0105 \mathrm{M} \mathrm{HCl}$ to reach the equivalence point in the titration of $25.0 \mathrm{~mL}$. of aqueous ammonia.
(a) What was the concentration of $\mathrm{NH}_3$ in the original ammonia solution?
(b) What are the concentrations of $\mathrm{H}_3 \mathrm{O}^{+}, \mathrm{OH}^{-}$, and $\mathrm{NH}_4{ }^{+}$at the equivalence point?
(c) What is the $\mathrm{pH}$ of the solution at the equivalence point?

David Collins

Numerade Educator

Problem 34

A titration of $25.0 \mathrm{~mL}$ of a solution of the weak base aniline, $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2$, requires $25.67 \mathrm{~mL}$ of $0.175 \mathrm{M} \mathrm{HCl}$ to reach the equivalence point.
(a) What was the concentration of aniline in the original solution?
(b) What are the concentrations of $\mathrm{H}_3 \mathrm{O}^{+}, \mathrm{OH}^{-}$, and $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}$at the equivalence point?
(c) What is the $\mathrm{pH}$ of the solution at the equivalence point?

David Collins

Numerade Educator

Problem 35

Without doing detailed calculations, sketch the curve for the titration of $30.0 \mathrm{~mL}$ of $0.10 \mathrm{M} \mathrm{NaOH}$ with $0.10 \mathrm{M} \mathrm{HCl}$. Indicate the approximate $\mathrm{pH}$ at the beginning of the titration and at the equivalence point. What is the total solution volume at the equivalence point?

CS

Connor Siggins

Numerade Educator

Problem 36

Without doing detailed calculations, sketch the curve for the titration of $50 \mathrm{~mL}$ of $0.050 \mathrm{M}$ pyridine, $\mathrm{C}_5 \mathrm{H}_5 \mathrm{~N}$ (a weak base), with $0.10 \mathrm{M} \mathrm{HCl}$. Indicate the approximate $\mathrm{pH}$ at the beginning of the titration and at the equivalence point. What is the total solution volume at the equivalence point?

David Collins

Numerade Educator

Problem 37

You titrate $25.0 \mathrm{~mL}$ of $0.10 \mathrm{M} \mathrm{NH}_3$ with $0.10 \mathrm{M} \mathrm{HCl}$.
(a) What is the $\mathrm{pH}$ of the $\mathrm{NH}_3$ solution before the titration begins?
(b) What is the $\mathrm{pH}$ at the equivalence point?
(c) What is the $\mathrm{pH}$ at the halfway point of the titration?
(d) What indicator in Figure 17.11 could be used to detect the equivalence point?
(e) Calculate the $\mathrm{pH}$ of the solution after adding $5.00,15.0,20.0,22.0$, and $30.0 \mathrm{~mL}$ of the acid. Combine this information with that in parts (a)-(c) and plot the titration curve.

David Collins

Numerade Educator

Problem 38

Construct a rough plot of $\mathrm{pH}$ versus volume of base for the titration of $25.0 \mathrm{~mL}$ of $0.050 \mathrm{M} \mathrm{HCN}$ with $0.075 \mathrm{M} \mathrm{NaOH}$.
(a) What is the $\mathrm{pH}$ before any $\mathrm{NaOH}$ is added?
(b) What is the $\mathrm{pH}$ at the halfway point of the titration?
(c) What is the $\mathrm{pH}$ when $95 \%$ of the required $\mathrm{NaOH}$ has been added?
(d) What volume of base, in milliliters, is required to reach the equivalence point?
(e) What is the $\mathrm{pH}$ at the equivalence point?
(f) What indicator would be most suitable for this titration? (Figure 17.11.)
(g) What is the $\mathrm{pH}$ when $105 \%$ of the required base has been added?

David Collins

Numerade Educator

Problem 39

Using Figure 17.11, suggest an indicator to use in each of the following titrations:
(a) The weak base pyridine is titrated with $\mathrm{HCl}$.
(b) Formic acid is titrated with $\mathrm{NaOH}$.
(c) Ethylenediamine, a weak diprotic base, is titrated with $\mathrm{HCl}$.

David Collins

Numerade Educator

Problem 40

Using Figure 17.11, suggest an indicator to use in each of the following titrations.
(a) $\mathrm{NaHCO}_3$ is titrated to $\mathrm{CO}_3{ }^{2-}$ with $\mathrm{NaOH}$.
(b) Hypochlorous acid is titrated with $\mathrm{NaOH}$.
(c) Trimethylamine is titrated with $\mathrm{HCl}$.

David Collins

Numerade Educator

Problem 41

Name two insoluble salts of each of the following ions.
(a) $\mathrm{Cl}^{-}$
(b) $\mathrm{Zn}^{2+}$
(c) $\mathrm{Fe}^{2+}$

CS

Connor Siggins

Numerade Educator

Problem 42

Name two insoluble salts of each of the following ions.
(a) $\mathrm{CO}_3^{2-}$
(b) $\mathrm{Ba}^{2+}$
(c) $\mathrm{I}^{-}$

CS

Connor Siggins

Numerade Educator

Problem 43

Using the solubility guidelines (Figure 3.10, page 150), predict whether each of the following is insoluble or soluble in water.
(a) $\left(\mathrm{NH}_4\right)_2 \mathrm{CO}_3$
(c) $\mathrm{NiS}$
(b) $\mathrm{ZnSO}_4$
(d) $\mathrm{BaSO}_4$

David Collins

Numerade Educator

Problem 44

Predict whether each of the following is insoluble or soluble in water.
(a) $\mathrm{Ni}(\mathrm{OH})_2$
(c) $\mathrm{MgCl}_2$
(b) $\mathrm{Zn}\left(\mathrm{NO}_3\right)_2$
(d) $\mathrm{K}_2 \mathrm{~S}$

Eileen Sullivan

Eileen Sullivan

Numerade Educator

Problem 45

For each of the following insoluble salts, (i) write a balanced equation showing the equilibrium occurring when the salt is added to water, and
(ii) write the $K_{\text {sp }}$ expression.
(a) $\mathrm{AgCN}$
(b) $\mathrm{NiCO}_3$
(c) $\mathrm{AuBr}_3$

CS

Connor Siggins

Numerade Educator

Problem 46

For each of the following insoluble salts, (i) write a balanced equation showing the equilibrium occurring when the salt is added to water, and (ii) write the $K_{\text {sp }}$ expression.
(a) $\mathrm{CaCO}_3$
(b) $\mathrm{PbBr}_2$
(c) $\mathrm{Ag}_2 \mathrm{~S}$

David Collins

Numerade Educator

Problem 47

When $1.55 \mathrm{~g}$ of solid thallium(I) bromide is added to $1.00 \mathrm{~L}$ of water, the salt dissolves to a small extent.
$$
\mathrm{TlBr}(\mathrm{s}) \rightleftharpoons \mathrm{T1}^{+}(\mathrm{aq})+\mathrm{Br}^{-}(\mathrm{aq})
$$

The thallium(I) and bromide ions in equilibrium with $\mathrm{T} 1 \mathrm{Br}$ each have a concentration of $1.9 \times 10^{-3} \mathrm{M}$. What is the value of $K_{\mathrm{sp}}$ for $\mathrm{T1Br}$ ?

David Collins

Numerade Educator

Problem 48

At $20^{\circ} \mathrm{C}$, a saturated aqueous solution of silver acetate, $\mathrm{AgCH}_3 \mathrm{CO}_2$, contains $1.0 \mathrm{~g}$ of the silver compound dissolved in $100.0 \mathrm{~mL}$ of solution. Calculate $K_{\text {sp }}$ for silver acetate.
$$
\mathrm{AgCH}_3 \mathrm{CO}_2(\mathrm{~s}) \rightleftarrows \mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{CH}_3 \mathrm{CO}_2^{-}(\mathrm{aq})
$$

David Collins

Numerade Educator

Problem 49

When $250 \mathrm{mg}$ of $\mathrm{SrF}_2$, strontium fluoride, is added to $1.00 \mathrm{~L}$ of water, the salt dissolves to a very small extent.
$$
\mathrm{SrF}_2(\mathrm{~s}) \rightleftarrows \mathrm{Sr}^{2+}(\mathrm{aq})+2 \mathrm{~F}^{-}(\mathrm{aq})
$$

At equilibrium, the concentration of $\mathrm{Sr}^{2+}$ is found to be $1.03 \times 10^{-3} \mathrm{M}$. What is the value of $K_{\text {sp }}$ for $\mathrm{SrF}_2$ ?

David Collins

Numerade Educator

Problem 50

Calcium hydroxide, $\mathrm{Ca}(\mathrm{OH})_2$, dissolves in water to the extent of $0.824 \mathrm{~g}$ per liter. What is the value of $K_{\mathrm{sp}}$ for $\mathrm{Ca}(\mathrm{OH})_2$ ?
$$
\mathrm{Ca}(\mathrm{OH})_2(\mathrm{~s}) \rightleftarrows \mathrm{Ca}^{2+}(\mathrm{aq})+2 \mathrm{OH}^{-}(\mathrm{aq})
$$

David Collins

Numerade Educator

Problem 51

You add $0.979 \mathrm{~g}$ of $\mathrm{Pb}(\mathrm{OH})_2$ to $1.00 \mathrm{~L}$ of pure water at $25{ }^{\circ} \mathrm{C}$. The $\mathrm{pH}$ is 9.15 . Estimate the value of $K_{\mathrm{sp}}$ for $\mathrm{Pb}(\mathrm{OH})_2$.

CS

Connor Siggins

Numerade Educator

Problem 52

You place $1.234 \mathrm{~g}$ of solid $\mathrm{Ca}(\mathrm{OH})_2$ in $1.00 \mathrm{~L}$ of pure water at $25^{\circ} \mathrm{C}$. The $\mathrm{pH}$ of the solution is found to be 12.35. Estimate the value of $K_{\mathrm{sp}}$ for $\mathrm{Ca}(\mathrm{OH})_2$.

David Collins

Numerade Educator

Problem 53

Estimate the solubility of silver iodide in pure water at $25^{\circ} \mathrm{C}$ (a) in moles per liter and (b) in grams per liter.
$$
\mathrm{AgI}(\mathrm{s}) \rightleftharpoons \mathrm{Ag}^{+}(\mathrm{aq})+\mathrm{I}^{-}(\mathrm{aq})
$$

Ronald Prasad

Numerade Educator

Problem 54

What is the molar concentration of $\mathrm{Au}^{+}(\mathrm{aq})$ in a saturated solution of $\mathrm{AuCl}$ in pure water at $25^{\circ} \mathrm{C}$ ?
$$
\mathrm{AuCl}(\mathrm{s}) \rightleftarrows \mathrm{Au}^{+}(\mathrm{aq})+\mathrm{Cl}^{-}(\mathrm{aq})
$$

David Collins

Numerade Educator

Problem 55

Estimate the solubility of calcium fluoride, $\mathrm{CaF}_2$, (a) in moles per liter and (b) in grams per liter of pure water.
$$
\mathrm{CaF}_2(\mathrm{~s}) \rightleftarrows \mathrm{Ca}^{2+}(\mathrm{aq})+2 \mathrm{~F}^{-}(\mathrm{aq})
$$

CS

Connor Siggins

Numerade Educator

Problem 56

Estimate the solubility of lead(II) iodide (a) in moles per liter and (b) in grams per liter of pure water.

David Collins

Numerade Educator

Problem 57

The $K_{\text {sp }}$ value for radium sulfate, $\mathrm{RaSO}_4$, is $4.2 \times 10^{-11}$. If $25 \mathrm{mg}$ of radium sulfate is placed in $1.00 \times 10^2 \mathrm{~mL}$ of water, does all of it dissolve? If not, how much dissolves?

David Collins

Numerade Educator

Problem 58

If $25 \mathrm{mg}$ of barium fluoride is placed in $250 \mathrm{~mL}$. of pure water, does all of it dissolve? If not, how much dissolves?

Manik Pulyani

Numerade Educator

Problem 59

Use $K_{\mathrm{sp}}$ values to decide which compound in each of the following pairs is more soluble (Appendix J).
(a) $\mathrm{PbCl}_2$ or $\mathrm{PbBr}_2$
(b) $\mathrm{HgS}$ or $\mathrm{FeS}$
(c) $\mathrm{Fe}(\mathrm{OH})_2$ or $\mathrm{Zn}(\mathrm{OH})_2$

David Collins

Numerade Educator

Problem 60

Use $K_{\text {sp }}$ values to decide which compound in each of the following pairs is more soluble (Appendix J).
(a) $\mathrm{AgCl}$ or $\mathrm{AgSCN}$
(b) $\mathrm{PbCO}_3$ or $\mathrm{PbSO}_4$
(c) $\mathrm{AgCl}$ or $\mathrm{MgF}_2$
(d) $\mathrm{SrF}_2$ or $\mathrm{PbF}_2$

David Collins

Numerade Educator

Problem 61

Use $K_{\text {sp }}$ values to decide which compound in each of the following pairs is more soluble (Appendix J).
(a) $\mathrm{TlBr}$ or $\mathrm{PbBr}_2$
(b) $\mathrm{AuCl}$ or $\mathrm{Hg}_2 \mathrm{Cl}_2$
(c) Tll or $\mathrm{Hg}_2 \mathrm{I}_2$

David Collins

Numerade Educator

Problem 62

Use $K_{\text {sp }}$ values to decide which compound in each of the following pairs is more soluble (Appendix J).
(a) $\mathrm{BaCO}_3$ or $\mathrm{Ag}_2 \mathrm{CO}_3$
(b) TII or $\mathrm{PbI}_2$
(c) $\mathrm{AgBr}$ or $\mathrm{Hg}_2 \mathrm{Br}_2$

David Collins

Numerade Educator

Problem 63

Calculate the molar solubility of silver thiocyanate, $\mathrm{AgSCN}$, in pure water and in water containing $0.010 \mathrm{M} \mathrm{NaSCN}$.

David Collins

Numerade Educator

Problem 64

Calculate the solubility of silver bromide, $\mathrm{AgBr}$, in moles per liter, in pure water. Compare this value with the molar solubility of $\mathrm{AgBr}$ in $225 \mathrm{~mL}$ of water to which $0.15 \mathrm{~g}$ of $\mathrm{NaBr}$ was added.

David Collins

Numerade Educator

Problem 65

Compare the solubility, in milligrams per milliliter, of silver iodide, $\mathrm{AgI}$, (a) in pure water and (b) in water that is $0.020 \mathrm{M}$ in $\mathrm{AgNO}_3$.

Ronald Prasad

Numerade Educator

Problem 66

What is the solubility, in milligrams per milliliter, of $\mathrm{BaF}_2$ (a) in pure water and (b) in water containing $5.0 \mathrm{mg} / \mathrm{mL} \mathrm{KF}$ ?

David Collins

Numerade Educator

Problem 67

Calculate the solubility, in moles per liter, of iron(II) hydroxide, $\mathrm{Fe}(\mathrm{OH})_2$, in a solution buffered to a $\mathrm{pH}$ of 7.00 .

Aadit Sharma

Numerade Educator

Problem 68

Calculate the solubility, in moles per liter, of magnesium hydroxide, $\mathrm{Mg}(\mathrm{OH})_2$, in a solution buffered to a $\mathrm{pH}$ of 9.50 .

Aadit Sharma

Numerade Educator

Problem 69

Which insoluble compound in each pair should be more soluble in nitric acid than in pure water?
(a) $\mathrm{PbCl}_2$ or $\mathrm{PbS}$
(b) $\mathrm{Ag}_2 \mathrm{CO}_3$ or $\mathrm{AgI}$
(c) $\mathrm{Al}(\mathrm{OH})_3$ or $\mathrm{AgCl}$

Ronald Prasad

Numerade Educator

Problem 70

Which compound in each pair should be more soluble in nitric acid than in pure water?
(a) $\mathrm{AgCN}$ or $\mathrm{AgBr}$
(b) $\mathrm{PbF}_2$ or $\mathrm{PbI}_2$
(c) $\mathrm{CuI}$ or $\mathrm{Cu}(\mathrm{OH})_2$

Ronald Prasad

Numerade Educator

Problem 71

Which compound in each pair should be more soluble in water than is predicted by a calculation from $K_{\mathrm{sp}}$ ?
(a) $\mathrm{AgCl}$ or $\mathrm{AgCN}$
(b) $\mathrm{Ag}_2 \mathrm{C}_2 \mathrm{O}_4$ or $\mathrm{AgBr}$
(c) $\mathrm{Hg}_2 \mathrm{I}_2$ or $\mathrm{Hg}_2 \mathrm{CO}_3$

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 72

Which compound in each pair is more soluble in water than is predicted by a calculation from $K_{\mathrm{sp}}$ ?
(a) $\mathrm{AgI}$ or $\mathrm{Ag}_2 \mathrm{CO}_3$
(b) $\mathrm{PbCO}_3$ or $\mathrm{PbCl}_2$
(c) $\mathrm{AgCl}$ or $\mathrm{AgCN}$

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 73

You have a solution that has a lead(II) ion concentration of $0.0012 \mathrm{M}$. If enough soluble chloride-containing salt is added so that the $\mathrm{Cl}^{-}$ concentration is $0.010 \mathrm{M}$, will $\mathrm{PbCl}_2$ precipitate?

David Collins

Numerade Educator

Problem 74

Sodium carbonate is added to a solution in which the concentration of $\mathrm{Ni}^{2+}$ ion is $0.0024 \mathrm{M}$. Will precipitation of $\mathrm{NiCO}_3$ occur (a) when the concentration of the carbonate ion is $1.0 \times 10^{-6} \mathrm{M}$ or (b) when it is 100 times greater $\left(1.0 \times 10^{-4} \mathrm{M}\right)$ ?

David Collins

Numerade Educator

Problem 75

If the concentration of $\mathrm{Zn}^{2+}$ in $10.0 \mathrm{~mL}$ of water is $1.63 \times 10^{-4} \mathrm{M}$, will zinc hydroxide, $\mathrm{Zn}(\mathrm{OH})_2$, precipitate when $4.0 \mathrm{mg}$ of $\mathrm{NaOH}$ is added?

Ronald Prasad

Numerade Educator

Problem 76

You have $95 \mathrm{~mL}$ of a solution that has a lead(II) concentration of $0.0012 \mathrm{M}$. Will $\mathrm{PbCl}_2$ precipitate when $1.20 \mathrm{~g}$ of solid $\mathrm{NaCl}$ is added?

David Collins

Numerade Educator

Problem 77

If the concentration of $\mathrm{Mg}^{2+}$ ion in seawater is $1350 \mathrm{mg} / \mathrm{L}$, what $\mathrm{OH}^{-}$concentration is required to precipitate $\mathrm{Mg}(\mathrm{OH})_2$ ?

Ronald Prasad

Numerade Educator

Problem 78

Will a precipitate of $\mathrm{Ca}(\mathrm{OH})_2$ form when $25.0 \mathrm{~mL}$. of $0.010 \mathrm{M} \mathrm{NaOH}$ is combined with $125.0 \mathrm{~mL}$ of a $0.10 \mathrm{M}$ solution of calcium chloride?

David Collins

Numerade Educator

Problem 79

Zinc hydroxide is amphoteric (Section 16.10). Use equilibrium constants to show that, given sufficient $\mathrm{OH}^{-}, \mathrm{Zn}(\mathrm{OH})_2$ can dissolve in $\mathrm{NaOH}$.

David Collins

Numerade Educator

Problem 80

. Solid silver iodide, Agl, can be dissolved by adding aqueous sodium cyanide. Calculate $K_{\text {net }}$ for the following reaction.
$$
\mathrm{AgI}(\mathrm{s})+2 \mathrm{CN}^{-}(\mathrm{aq}) \rightleftarrows\left[\mathrm{Ag}(\mathrm{CN})_2\right\rfloor^{-}(\mathrm{aq})+\mathrm{I}^{-}(\mathrm{aq})
$$

David Collins

Numerade Educator

Problem 81

What amount of ammonia (moles) must be added to dissolve $0.050 \mathrm{~mol}$ of $\mathrm{AgCl}$ suspended in $1.0 \mathrm{~L}$ of water?

David Collins

Numerade Educator

Problem 82

Can you dissolve $15.0 \mathrm{mg}$ of $\mathrm{AuCl}$ in $100.0 \mathrm{~mL}$ of water if you add $15.0 \mathrm{~mL}$ of $6.00 \mathrm{M} \mathrm{NaCN}$ ?

David Collins

Numerade Educator

Problem 83

What is the solubility of $\mathrm{AgCl}$ (a) in pure water and (b) in $1.0 \mathrm{M} \mathrm{NH}_3$ ?

David Collins

Numerade Educator

Problem 84

The chemistry of silver cyanide:
(a) Calculate the solubility of $\mathrm{AgCN}(\mathrm{s})$ in water from the $K_{\text {sp }}$ value.
(b) Calculate the value of the equilibrium constant for the reaction
$$
\mathrm{AgCN}(\mathrm{s})+\mathrm{CN}^{-}(\mathrm{aq}) \rightleftarrows\left[\mathrm{Ag}(\mathrm{CN})_2\right]^{-}(\mathrm{aq})
$$
from $K_{\mathrm{sp}}$ and $K_{\mathrm{f}}$ values and predict from this value whether $\mathrm{AgCN}(\mathrm{s})$ would dissolve in KCN(aq).
(c) Determine the equilibrium constant for the reaction
$$
\begin{aligned}
& \mathrm{AgCN}(\mathrm{s})+2 \mathrm{~S}_2 \mathrm{O}_3{ }^{2-}(\mathrm{aq}) \rightleftarrows \\
& {\left[\mathrm{Ag}\left(\mathrm{S}_2 \mathrm{O}_3\right)_2\right]^{3-}(\mathrm{aq})+\mathrm{CN}^{-}(\mathrm{aq})} \\
&
\end{aligned}
$$

Calculate the solubility of $\mathrm{AgCN}$ in a solution containing $0.10 \mathrm{M} \mathrm{S}_2 \mathrm{O}_3{ }^{2-}$ and compare the value to the solubility in water [part (a)].

David Collins

Numerade Educator

Problem 85

In each of the following cases, decide whether a precipitate will form when mixing the indicated reagents, and write a balanced equation for the reaction.
(a) $\mathrm{NaBr}(\mathrm{aq})+\mathrm{AgNO}_3(\mathrm{aq})$
(b) $\mathrm{KCl}(\mathrm{aq})+\mathrm{Pb}\left(\mathrm{NO}_3\right)_2(\mathrm{aq})$

David Collins

Numerade Educator

Problem 86

In each of the following cases, decide whether a precipitate will form when mixing the indicated reagents, and write a balanced equation for the reaction.
(a) $\mathrm{Na}_2 \mathrm{SO}_4(\mathrm{aq})+\mathrm{Mg}\left(\mathrm{NO}_3\right)_2(\mathrm{aq})$
(b) $\mathrm{K}_3 \mathrm{PO}_4(\mathrm{aq})+\mathrm{FeCl}_3(\mathrm{aq})$

David Collins

Numerade Educator

Problem 87

If you mix $48 \mathrm{~mL}$ of $0.0012 \mathrm{M} \mathrm{BaCl}_2$ with $24 \mathrm{~mL}$ of $1.0 \times 10^{-6} \mathrm{M} \mathrm{Na}_2 \mathrm{SO}_4$, will a precipitate of $\mathrm{BaSO}_4$ form?

Ronald Prasad

Numerade Educator

Problem 88

Calculate the hydronium ion concentration and the $\mathrm{pH}$ of the solution that results when $20.0 \mathrm{~mL}$. of $0.15 \mathrm{M}$ acetic acid, $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}$, is mixed with $5.0 \mathrm{~mL}$ of $0.17 \mathrm{M} \mathrm{NaOH}$.

David Collins

Numerade Educator

Problem 89

Calculate the hydronium ion concentration and the $\mathrm{pH}$ of the solution that results when $50.0 \mathrm{~mL}$. of $0.40 \mathrm{M} \mathrm{NH}_3$ is mixed with $25.0 \mathrm{~mL}$ of $0.20 \mathrm{M}$ $\mathrm{HCl}$.

Ronald Prasad

Numerade Educator

Problem 90

For each of the following cases, decide whether the $\mathrm{pH}$ is less than 7 , equal to 7 , or greater than 7 .
(a) Equal volumes of $0.20 \mathrm{M}$ ammonia, $\mathrm{NH}_3$, and $0.20 \mathrm{M} \mathrm{HCl}$ are mixed.
(b) Equal volumes of $0.10 \mathrm{M}$ acetic acid, $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}$, and $0.10 \mathrm{M} \mathrm{KOH}$ are mixed.
(c) $25 \mathrm{~mL}$ of $0.015 \mathrm{M} \mathrm{NH}_3$ is mixed with $12 \mathrm{~mL}$ of $0.015 \mathrm{M} \mathrm{HCl}$.
(d) $150 \mathrm{~mL}$ of $0.20 \mathrm{M} \mathrm{HNO}_3$ is mixed with $75 \mathrm{~mL}$ of $0.40 \mathrm{M} \mathrm{NaOH}$.
(e) $25 \mathrm{~mL}$ of $0.45 \mathrm{M} \mathrm{H}_2 \mathrm{SO}_4$ is mixed with $25 \mathrm{~mL}$. of $0.90 \mathrm{M} \mathrm{NaOH}$.

David Collins

Numerade Educator

Problem 91

Rank the following compounds in order of increasing solubility in water: $\mathrm{Na}_2 \mathrm{CO}_3, \mathrm{BaCO}_3$, $\mathrm{Ag}_2 \mathrm{CO}_3$.

David Collins

Numerade Educator

Problem 92

A sample of hard water contains about $2.0 \times 10^{-3} \mathrm{M} \mathrm{Ca}^{2+}$. A soluble fluoridecontaining salt such as $\mathrm{NaF}$ is added to fluoridate the water (to aid in the prevention of dental cavities). What is the maximum concentration of $\mathrm{F}^{-}$that can be present without precipitating $\mathrm{CaF}_2$ ?

David Collins

Numerade Educator

Problem 93

What is the $\mathrm{pH}$ of a buffer solution prepared from $5.15 \mathrm{~g}$ of $\mathrm{NH}_4 \mathrm{NO}_3$ and $100 . \mathrm{mL}$ of $0.15 \mathrm{M} \mathrm{NH}_3$ ? What is the new $\mathrm{pH}$ if the solution is diluted with pure water to a volume of $500 . \mathrm{mL}$ ?

Ronald Prasad

Numerade Educator

Problem 94

If you place $5.0 \mathrm{mg}$ of $\mathrm{SrSO}_4$ in $1.0 \mathrm{~L}$ of pure water, will all of the salt dissolve before equilibrium is established, or will some salt remain undissolved?

David Collins

Numerade Educator

Problem 95

Describe the effect on the $\mathrm{pH}$ of the following actions or explain why there is no effect:
(a) Adding sodium acetate, $\mathrm{NaCH}_3 \mathrm{CO}_2$, to
$$
0.100 \mathrm{M} \mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}
$$
(b) Adding $\mathrm{NaNO}_3$ to $0.100 \mathrm{M} \mathrm{HNO}_3$

Ronald Prasad

Numerade Educator

Problem 96

What volume of $0.120 \mathrm{M} \mathrm{NaOH}$ must be added to $100 . \mathrm{mL}$ of $0.100 \mathrm{M} \mathrm{NaHC}_2 \mathrm{O}_4$ to reach a $\mathrm{pH}$ of 4.70 ?

David Collins

Numerade Educator

Problem 97

A buffer solution is prepared by dissolving $1.50 \mathrm{~g}$ each of benzoic acid, $\mathrm{C}_6 \mathrm{H}_5 \mathrm{CO}_2 \mathrm{H}$, and sodium benzoate, $\mathrm{NaC}_6 \mathrm{H}_5 \mathrm{CO}_2$, in $150.0 \mathrm{~mL}$ of solution.
(a) What is the $\mathrm{pH}$ of this buffer solution?
(b) Which buffer component must be added, and in what quantity, to change the $\mathrm{pH}$ to 4.00 ?
(c) What quantity of $2.0 \mathrm{M} \mathrm{NaOH}$ or $2.0 \mathrm{M} \mathrm{HCl}$ must be added to the buffer to change the $\mathrm{pH}$ to 4.00 ?

David Collins

Numerade Educator

Problem 98

What volume of $0.200 \mathrm{M} \mathrm{HCl}$ must be added to $500.0 \mathrm{~mL}$ of $0.250 \mathrm{M} \mathrm{NH}_3$ to have a buffer with a $\mathrm{pH}$ of 9.00 ?

David Collins

Numerade Educator

Problem 99

What is the equilibrium constant for the following reaction?
$$
\mathrm{AgCl}(\mathrm{s})+\mathrm{I}^{-}(\mathrm{aq}) \rightleftarrows \mathrm{AgI}(\mathrm{s})+\mathrm{Cl}^{-}(\mathrm{aq})
$$

Does the equilibrium lie predominantly to the left or to the right? Will Agl form if iodide ion, $\mathrm{I}^{-}$, is added to a saturated solution of $\mathrm{AgCl}$ ?

David Collins

Numerade Educator

Problem 100

Calculate the equilibrium constant for the following reaction.
$$
\begin{aligned}
& \mathrm{Zn}(\mathrm{OH})_2(\mathrm{~s})+2 \mathrm{CN}^{-}(\mathrm{aq}) \rightleftharpoons \\
& \mathrm{Zn}(\mathrm{CN})_2(\mathrm{~s})+2 \mathrm{OH}^{-}(\mathrm{aq}) \\
&
\end{aligned}
$$

Does the equilibrium lie predominantly to the left or to the right?

David Collins

Numerade Educator

Problem 101

Suppose you harvest $28 \mathrm{~g}$ of rhubarb leaves with an oxalic acid content of $1.2 \%$ by weight.
(a) What volume of $0.25 \mathrm{M} \mathrm{NaOH}$ is required to titrate completely the oxalic acid in the leaves?
(b) What mass of calcium oxalate could be formed from the oxalic acid in these leaves?

Daniel Kyinakwa

Daniel Kyinakwa

Numerade Educator

Problem 102

The solubility product constant for calcium oxalate is estimated to be $4 \times 10^{-9}$. What is its solubility in grams per liter?

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 103

In principle, the ions $\mathrm{Ba}^{2+}$ and $\mathrm{Ca}^{2+}$ can be separated by the difference in solubility of their fluorides, $\mathrm{BaF}_2$ and $\mathrm{CaF}_2$. If you have a solution that is $0.10 \mathrm{M}$ in both $\mathrm{Ba}^{2+}$ and $\mathrm{Ca}^{2+}, \mathrm{CaF}_2$ will begin to precipitate first as fluoride ion is added slowly to the solution.
(a) What concentration of fluoride ion will precipitate the maximum amount of $\mathrm{Ca}^{2+}$ ion without precipitating $\mathrm{BaF}_2$ ?
(b) What concentration of $\mathrm{Ca}^{2+}$ remains in solution when $\mathrm{BaF}_2$ just begins to precipitate?

David Collins

Numerade Educator

Problem 104

A solution contains $0.10 \mathrm{M}$ iodide ion, $\mathrm{I}^{-}$, and $0.10 \mathrm{M}$ carbonate ion, $\mathrm{CO}_3{ }^{2-}$.
(a) If solid $\mathrm{Pb}\left(\mathrm{NO}_3\right)_2$ is slowly added to the solution, which salt will precipitate first, $\mathrm{PbI}_2$ or $\mathrm{PbCO}_3$ ?
(b) What will be the concentration of the first ion that precipitates $\left(\mathrm{CO}_3{ }^{2-}\right.$ or $\left.\mathrm{I}^{-}\right)$when the second, more soluble salt begins to precipitate?

David Collins

Numerade Educator

Problem 105

A solution contains $\mathrm{Ca}^{2+}$ and $\mathrm{Pb}^{2+}$ ions, both at a concentration of $0.010 \mathrm{M}$. You wish to separate the two ions from each other as completely as possible by precipitating one but not the other using aqueous $\mathrm{Na}_2 \mathrm{SO}_4$ as the precipitating agent.
(a) Which will precipitate first as sodium sulfate is added, $\mathrm{CaSO}_4$ or $\mathrm{PbSO}_4$ ?
(b) What will be the concentration of the first ion that precipitates $\left(\mathrm{Ca}^{2+}\right.$ or $\left.\mathrm{Pb}^{2+}\right)$ when the second, more soluble salt begins to precipitate?

David Collins

Numerade Educator

Problem 106

Buffer capacity is defined as the number of moles of a strong acid or strong base required to change the $\mathrm{pH}$ of $1 \mathrm{~L}$ of the buffer solution by one unit. What is the buffer capacity of a solution that is $0.10 \mathrm{M}$ in acetic acid and $0.10 \mathrm{M}$ in sodium acetate?

David Collins

Numerade Educator

Problem 107

Some photographic film is coated with crystals of $\mathrm{AgBr}$ suspended in gelatin. Some of the silver ions are reduced to silver metal upon exposure to light. Unexposed $\mathrm{AgBr}$ is then dissolved with sodium thiosulfate in the fixing step.
$$
\begin{aligned}
& \mathrm{AgBr}(\mathrm{s})+2 \mathrm{~S}_2 \mathrm{O}_3{ }^{2-}(\mathrm{aq}) \rightleftharpoons \\
& {\left[\mathrm{Ag}\left(\mathrm{S}_2 \mathrm{O}_3\right)_2\right]^{3-}(\mathrm{aq})+\mathrm{Br}^{-}(\mathrm{aq})} \\
&
\end{aligned}
$$
(a) What is the equilibrium constant for this reaction?
(b) What mass of $\mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3$ must be added to dissolve $1.00 \mathrm{~g}$ of $\mathrm{AgBr}$ suspended in $1.00 \mathrm{~L}$ of water?

David Collins

Numerade Educator

Problem 108

The $\mathrm{Ca}^{2+}$ ion in hard water is precipitated as $\mathrm{CaCO}_3$ by adding soda ash, $\mathrm{Na}_2 \mathrm{CO}_3$. If the calcium ion concentration in hard water is $0.010 \mathrm{M}$ and if the $\mathrm{Na}_2 \mathrm{CO}_3$ is added until the carbonate ion concentration is $0.050 \mathrm{M}$, what percentage of the calcium ions was removed from the water? (You may neglect carbonate ion hydrolysis.)

David Collins

Numerade Educator

Problem 109

Each pair of ions below is found together in aqueous solution. Using the table of solubility product constants in Appendix J, devise a way to separate these ions by adding a reagent to precipitate one of the ions as an insoluble salt and leaving the other in solution.
(a) $\mathrm{Ba}^{2+}$ and $\mathrm{Na}^{+}$
(b) $\mathrm{Ni}^{2+}$ and $\mathrm{Pb}^{2+}$

Ronald Prasad

Numerade Educator

Problem 110

Each pair of ions below is found together in aqueous solution. Using the table of solubility product constants in Appendix J, devise a way to separate these ions by adding a reagent to precipitate one of the ions as an insoluble salt and leave the other in solution.
(a) $\mathrm{Cu}^{2+}$ and $\mathrm{Ag}^{+}$
(b) $\mathrm{Al}^{3+}$ and $\mathrm{Fe}^{3+}$

David Collins

Numerade Educator

Problem 111

4 The cations $\mathrm{Ba}^{2+}$ and $\mathrm{Sr}^{2+}$ can be precipitated as very insoluble sulfates.
(a) If you add sodium sulfate to a solution containing these metal cations, each with a concentration of $0.10 \mathrm{M}$, which is precipitated first, $\mathrm{BaSO}_4$ or $\mathrm{SrSO}_4$ ?
(b) What will be the concentration of the first ion that precipitates ( $\mathrm{Ba}^{2+}$ or $\mathrm{Sr}^{2+}$ ) when the second, more soluble salt begins to precipitate?

David Collins

Numerade Educator

Problem 112

You will often work with salts of $\mathrm{Fe}^{3+}, \mathrm{Pb}^{2+}$, and $\mathrm{Al}^{3+}$ in the laboratory. (All are found in nature, and all are important economically.) If you have a solution containing these three ions, each at a concentration of $0.10 \mathrm{M}$, what is the order in which their hydroxides precipitate as aqueous $\mathrm{NaOH}$ is slowly added to the solution?

David Collins

Numerade Educator

Problem 113

Aniline hydrochloride, $\left(\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3\right) \mathrm{Cl}$, is a weak acid. (Its conjugate base is the weak base aniline, $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2$.) The acid can be titrated with a strong base such as $\mathrm{NaOH}$.
$$
\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}(\mathrm{aq})+\mathrm{OH}^{-}(\mathrm{aq}) \rightleftarrows \mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2(\mathrm{aq})+\mathrm{H}_2 \mathrm{O}(\ell)
$$

Assume $50.0 \mathrm{~mL}$ of $0.100 \mathrm{M}$ aniline hydrochloride is titrated with $0.185 \mathrm{M} \mathrm{NaOH}$. ( $K_2$ for aniline hydrochloride is $2.4 \times 10^{-5}$.)
(a) What is the $\mathrm{pH}$ of the $\left(\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3\right) \mathrm{Cl}$ solution before the titration begins?
(b) What is the $\mathrm{pH}$ at the equivalence point?
(c) What is the $\mathrm{pH}$ at the halfway point of the titration?
(d) Which indicator in Figure 17.11 could be used to detect the equivalence point?
(e) Calculate the $\mathrm{pH}$ of the solution after adding $10.0,20.0$, and $30.0 \mathrm{~mL}$ of base.
(f) Combine the information in parts (a), (b), (c), and (e), and plot an approximate titration curve.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 114

The weak base ethanolamine, $\mathrm{HOCH}_2 \mathrm{CH}_2 \mathrm{NH}_2$, can be titrated with $\mathrm{HCl}$.
$$
\begin{aligned}
\mathrm{HOCH}_2 \mathrm{CH}_2 \mathrm{NH}_2(\mathrm{aq})+\mathrm{H}_3 \mathrm{O}^{+}(\mathrm{aq}) \underset{\mathrm{HOCH}_2 \mathrm{CH}_2 \mathrm{NH}_3{ }^{+}(\mathrm{aq})+\mathrm{H}_2 \mathrm{O}(\ell)}{\rightleftarrows}
\end{aligned}
$$

Assume you have $25.0 \mathrm{~mL}$ of a $0.010 \mathrm{M}$ solution of ethanolamine and titrate it with $0.0095 \mathrm{M} \mathrm{HCl}$. ( $K_{\mathrm{b}}$ for ethanolamine is $3.2 \times 10^{-5}$.)
(a) What is the $\mathrm{pH}$ of the ethanolamine solution before the titration begins?
(b) What is the $\mathrm{pH}$ at the equivalence point?
(c) What is the $\mathrm{pH}$ at the halfway point of the titration?
(d) Which indicator in Figure 17.11 is the best choice to detect the equivalence point?
(e) Calculate the $\mathrm{pH}$ of the solution after adding $5.00,10.0,20.0$, and $30.0 \mathrm{~mL}$ of the acid.
(f) Combine the information in parts (a), (b), (c), and (e), and plot an approximate titration curve.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 115

For the titration of $50.0 \mathrm{~mL}$ of $0.150 \mathrm{M}$ ethylamine, $\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2$, with $0.100 \mathrm{M} \mathrm{HCl}$, find the $\mathrm{pH}$ at each of the following points, and then use that information to sketch the titration curve and decide on an appropriate indicator.
(a) At the beginning, before $\mathrm{HCl}$ is added
(b) At the halfway point in the titration
(c) When $75 \%$ of the required acid is added
(d) At the equivalence point
(e) When $10.0 \mathrm{~mL}$ more $\mathrm{HCl}$ is added than is required
(f) Sketch the titration curve.
(g) Suggest an appropriate indicator for this titration.

David Collins

Numerade Educator

Problem 116

. A buffer solution with a $\mathrm{pH}$ of 12.00 consists of $\mathrm{Na}_3 \mathrm{PO}_4$ and $\mathrm{Na}_2 \mathrm{HPO}_4$. The volume of solution is $200.0 \mathrm{~mL}$.
(a) Which component of the buffer is present in a larger amount?
(b) If the concentration of $\mathrm{Na}_3 \mathrm{PO}_4$ is $0.400 \mathrm{M}$, what mass of $\mathrm{Na}_2 \mathrm{HPO}_4$ is present?
(c) Which component of the buffer must be added to change the $\mathrm{pH}$ to 12.25 ? What mass of that component is required?

Ronald Prasad

Numerade Educator

Problem 117

To have a buffer with a $\mathrm{pH}$ of 2.50 , what volume of $0.150 \mathrm{M} \mathrm{NaOH}$ must be added to $100 . \mathrm{mL}$ of $0.230 \mathrm{M} \mathrm{H}_3 \mathrm{PO}_4$ ?

Victor Salazar

Numerade Educator

Problem 118

What mass of $\mathrm{Na}_3 \mathrm{PO}_4$ must be added to $80.0 \mathrm{~mL}$ of $0.200 \mathrm{M} \mathrm{HCl}$ to obtain a buffer with a $\mathrm{pH}$ of 7.75 ?

David Collins

Numerade Educator

Problem 119

You have a solution that contains $\mathrm{AgNO}_3$. $\mathrm{Pb}\left(\mathrm{NO}_3\right)_2$, and $\mathrm{Cu}\left(\mathrm{NO}_3\right)_2$. Devise a separation method that results in having $\mathrm{Ag}^{+}$in one test tube, $\mathrm{Pb}^{2+}$ in another, and $\mathrm{Cu}^{2+}$ in a third test tube. Use solubility guidelines and $K_{\text {sp }}$ and $K_{\mathrm{f}}$ values.

David Collins

Numerade Educator

Problem 120

Once you have separated the three salts in Study Question 119 into three test tubes, you need to confirm their presence.
(a) For $\mathrm{Pb}^{2+}$ ion, one way to do this is to treat a precipitate of $\mathrm{PbCl}_2$ with $\mathrm{K}_2 \mathrm{CrO}_4$ to produce the bright yellow insoluble solid, $\mathrm{PbCrO}_4$. Using $K_{\text {sp }}$ values, confirm that the chloride salt should be converted to the chromate salt.
(b) Suggest a method for confirming the presence of $\mathrm{Ag}^{+}$and $\mathrm{Cu}^{2+}$ ions using complex ions.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 121

Suggest a method for separating a precipitate consisting of a mixture of solid CuS and solid $\mathrm{Cu}(\mathrm{OH})_2$.

Iryna Ivaniuk

Numerade Educator

Problem 122

Which of the following barium salts should dissolve in a strong acid such as $\mathrm{HCl}: \mathrm{Ba}(\mathrm{OH})_2$ $\mathrm{BaSO}_4$, or $\mathrm{BaCO}_3$ ?

David Collins

Numerade Educator

Problem 123

Explain why the solubility of $\mathrm{Ag}_3 \mathrm{PO}_4$ can be greater in water than is calculated from the $K_{\text {sp }}$ value of the salt.

Sara Ross

Numerade Educator

Problem 124

Two acids, each approximately $0.01 \mathrm{M}$ in concentration, are titrated separately with a strong base. The acids show the following $\mathrm{pH}$ values at the equivalence point: $\mathrm{HA}, \mathrm{pH}=9.5$, and $\mathrm{HB}, \mathrm{pH}=8.5$.
(a) Which is the stronger acid, HA or $\mathrm{HB}$ ?
(b) Which of the conjugate bases, $\mathrm{A}^{-}$or $\mathrm{B}^{-}$, is the stronger base?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 125

Composition diagrams, commonly known as alpha plots, are often used to visualize the species in a solution of an acid or base as the $\mathrm{pH}$ is varied. The diagram for $0.100 \mathrm{M}$ acetic acid is shown here.
The plot shows how the fraction [alpha $(\alpha)]$ of acetic acid in solution,
$$
\alpha=\frac{\left[\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}\right]}{\left[\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}\right]+\left[\mathrm{CH}_3 \mathrm{CO}_2{ }^{-}\right]}
$$
changes as the $\mathrm{pH}$ increases (blue curve). (The red curve shows how the fraction of acetate ion, $\mathrm{CH}_3 \mathrm{CO}_2^{-}$, changes as the $\mathrm{pH}$ increases.) Alpha plots are another way of viewing the relative concentrations of acetic acid and acetate ion as a strong base is added to a solution of acetic acid in the course of a titration.
(a) Explain why the fraction of acetic acid declines and that of acetate ion increases as the $\mathrm{pH}$ increases.
(b) Which species predominates at a $\mathrm{pH}$ of 4 , acetic acid or acetate ion? What is the situation at a $\mathrm{pH}$ of 6 ?
(c) Consider the point where the two lines cross. The fraction of acetic acid in the solution is 0.5 , and so is that of acetate ion. That is, the solution is half acid and half conjugate base; their concentrations are equal. At this point, the graph shows the $\mathrm{pH}$ is 4.74 . Explain why the $\mathrm{pH}$ at this point is 4.74 .

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 126

The composition diagram, or alpha plot, for the important acid-base system of carbonic acid, $\mathrm{H}_2 \mathrm{CO}_3$, is illustrated. (See Study Question 125 for more information on such diagrams.)
(a) Explain why the fraction of bicarbonate ion, $\mathrm{HCO}_3{ }^{-}$, rises and then falls as the $\mathrm{pH}$ increases.
(b) What is the composition of the solution when the $\mathrm{pH}$ is 6.0 ? When the $\mathrm{pH}$ is 10.0 ?
(c) If you wanted to buffer a solution at a $\mathrm{pH}$ of 11.0, what should be the ratio of $\mathrm{HCO}_3^{-}$to $\mathrm{CO}_3{ }^{2-}$ ?

Tanvi Garg

Numerade Educator

Problem 127

The chemical name for aspirin is acetylsalicylic acid. It is believed that the analgesic and other desirable properties of aspirin are due not to the aspirin itself but rather to the simpler compound salicylic acid, $\mathrm{C}_6 \mathrm{H}_4(\mathrm{OH}) \mathrm{CO}_2 \mathrm{H}$, which results from the breakdown of aspirin in the stomach.
(a) Give approximate values for the following bond angles in the acid: (i) $\mathrm{C}-\mathrm{C}-\mathrm{C}$ in the ring; (ii) $\mathrm{O}-\mathrm{C}=\mathrm{O}$; (iii) either of the $\mathrm{C}-\mathrm{O}-\mathrm{H}$ angles; and (iv) $\mathrm{C}-\mathrm{C}-\mathrm{H}$.
(b) What is the hybridization of the $\mathrm{C}$ atoms of the ring? Of the $\mathrm{C}$ atom in the $-\mathrm{CO}_2 \mathrm{H}$ group?
(c) Experiment shows that $1.00 \mathrm{~g}$ of salicylic acid will dissolve in $460 \mathrm{~mL}$ of water. If the $\mathrm{pH}$ of this solution is 2.4 , what is $K_{\mathrm{a}}$ for the acid?
(d) If you have salicylic acid in your stomach and if the $\mathrm{pH}$ of gastric juice is 2.0 , calculate the percentage of salicylic acid present in the stomach in the form of the salicylate ion, $\mathrm{C}_6 \mathrm{H}_4(\mathrm{OH}) \mathrm{CO}_2^{-}$.
(e) Assume you have $25.0 \mathrm{~mL}$ of a $0.014 \mathrm{M}$ solution of salicylic acid and titrate it with $0.010 \mathrm{M}$ $\mathrm{NaOH}$. What is the $\mathrm{pH}$ at the halfway point of the titration? What is the $\mathrm{pH}$ at the equivalence point?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 128

Aluminum hydroxide reacts with phosphoric acid to give $\mathrm{AlPO}_4$. The substance is used industrially in adhesives, binders, and cements.
(a) Write the balanced equation for the preparation of $\mathrm{AlPO}_4$ from aluminum hydroxide and phosphoric acid.
(b) If you begin with $152 \mathrm{~g}$ of aluminum hydroxide and $3.00 \mathrm{~L}$ of $0.750 \mathrm{M}$ phosphoric acid, what is the theoretical yield of $\mathrm{AlPO}_4$ ?
(c) If you place $25.0 \mathrm{~g}$ of $\mathrm{AlPO}_4$ in $1.00 \mathrm{~L}$ of water, what are the concentrations of $\mathrm{Al}^{3+}$ and $\mathrm{PO}_4{ }^{3-}$ at equilibrium? (Neglect hydrolysis of aqueous $\mathrm{Al}^{3+}$ and $\mathrm{PO}_4^{3-}$ ions.) $K_{\text {sp }}$ for $\mathrm{AlPO}_4$ is $1.3 \times 10^{-20}$.
(d) Does the solubility of $\mathrm{AlPO}_4$ increase or decrease on adding $\mathrm{HCl}$ ? Explain.

Tanvi Garg

Numerade Educator