Chemistry

Julia Burdge

Chapter 17

Acid-Base Equilibria and Solubility Equilibria - all with Video Answers

Educators

Chapter Questions

Problem 1

Use Le Châtelier's principle to explain how the common ion effect affects the $\mathrm{pH}$ of a weak acid solution.

Aashna Calidas

Aashna Calidas

Numerade Educator

Problem 2

Describe the effect on $\mathrm{pH}$ (increase, decrease, or no change) that results from each of the following additions: (a) potassium acetate to an acetic acid solution, (b) ammonium nitrate to an ammonia solution, (c) sodium formate (HCOONa) to a formic acid (HCOOH) solution, (d) potassium chloride to a hydrochloric acid solution, (e) barium iodide to a hydroiodic acid solution.

Dyani Melgarejo

Dyani Melgarejo

Numerade Educator

Problem 3

Define $\mathrm{p} K_{\mathrm{a}}$ for a weak acid. What is the relationship between the value of the $\mathrm{p} K_{\mathrm{a}}$ and the strength of the acid?

Aashna Calidas

Numerade Educator

Problem 4

Define $\mathrm{p} K_{\mathrm{a}}$ for a weak acid. What is the relationship between the value of the $\mathrm{p} K_{\mathrm{a}}$ and the strength of the acid?

Aashna Calidas

Numerade Educator

Problem 5

Determine the $\mathrm{pH}$ of (a) a $0.40 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}$ solution and (b) a solution that is $0.40 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}$ and $0.20 \mathrm{M}$ $\mathrm{CH}_{3} \mathrm{COONa}$

Aadit Sharma

Numerade Educator

Problem 6

Determine the $\mathrm{pH}$ of (a) a $0.20 \mathrm{M} \mathrm{NH}_{3}$ solution, and (b) a solution that is $0.20 M \mathrm{NH}_{3}$ and $0.30 \mathrm{M} \mathrm{NH}_{4} \mathrm{Cl}$.

Aashna Calidas

Numerade Educator

Problem 7

What is a buffer solution? What must a solution contain to be a buffer?

Aashna Calidas

Numerade Educator

Problem 8

Using only a pH meter, water, and a graduated cylinder, how would you distinguish between an acid solution and a buffer solution at the same $\mathrm{pH} ?$

Aashna Calidas

Numerade Educator

Problem 9

Calculate the $\mathrm{pH}$ of the buffer system made up of $0.15 \mathrm{M}$ $\mathrm{NH}_{3} / 0.35 \mathrm{M} \mathrm{NH}_{4} \mathrm{Cl}$

Aadit Sharma

Numerade Educator

Problem 10

Calculate the $\mathrm{pH}$ of the following two buffer solutions:
(a) $2.0 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONa} / 2.0 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH},$
(b) $0.20 M$ $\mathrm{CH}_{3} \mathrm{COONa} / 0.20 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH} .$ Which is the more effective buffer? Why?

Aashna Calidas

Numerade Educator

Problem 11

The $\mathrm{pH}$ of a bicarbonate-carbonic acid buffer is 7.50 . Calculate the ratio of the concentration of carbonic acid $\left(\mathrm{H}_{2} \mathrm{CO}_{3}\right)$ to that of the bicarbonate ion $\left(\mathrm{HCO}_{3}^{-}\right)$

Sneha Hoysala

Duquesne University

Problem 12

What is the $\mathrm{pH}$ of the buffer $0.10 \mathrm{M} \mathrm{Na}_{2} \mathrm{HPO}_{4} / 0.15 \mathrm{M}$ $\mathrm{KH}_{2} \mathrm{PO}_{4} ?$

Aashna Calidas

Numerade Educator

Problem 13

The $\mathrm{pH}$ of a sodium acetate-acetic acid buffer is 4.50 . Calculate the ratio $\left[\mathrm{CH}_{3} \mathrm{COO}^{-}\right] /\left[\mathrm{CH}_{3} \mathrm{COOH}\right]$

Sneha Hoysala

Duquesne University

Problem 14

The $\mathrm{pH}$ of blood plasma is 7.40 . Assuming the principal buffer system is $\mathrm{HCO}_{3}^{-} / \mathrm{H}_{2} \mathrm{CO}_{3},$ calculate the ratio $\left[\mathrm{HCO}_{3}^{-}\right] /\left[\mathrm{H}_{2} \mathrm{CO}_{3}\right] .$ Is this buffer more effective against an added acid or an added base?

Aashna Calidas

Numerade Educator

Problem 15

Calculate the $\mathrm{pH}$ of the $0.20 \mathrm{M} \mathrm{NH}_{3} / 0.20 \mathrm{M} \mathrm{NH}_{4} \mathrm{Cl}$ buffer. What is the $\mathrm{pH}$ of the buffer after the addition of $10.0 \mathrm{~mL}$ of $0.10 \mathrm{M} \mathrm{HCl}$ to $65.0 \mathrm{~mL}$ of the buffer?

Sneha Hoysala

Duquesne University

Problem 16

Calculate the $\mathrm{pH}$ of $1.00 \mathrm{~L}$ of the buffer $1.00 \mathrm{M}$ $\mathrm{CH}_{3} \mathrm{COONa} / 1.00 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}$ before and after the
addition of (a) $0.080 \mathrm{~mol} \mathrm{NaOH}$ and (b) $0.12 \mathrm{~mol} \mathrm{HCl}$. (Assume that there is no change in volume.)

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 17

Which of the following solutions can act as a buffer: (a) $\mathrm{KCl} / \mathrm{HCl},(\mathrm{b}) \mathrm{KHSO}_{4} / \mathrm{H}_{2} \mathrm{SO}_{4},$ (c) $\mathrm{Na}_{2} \mathrm{HPO}_{4} /$
$\mathrm{NaH}_{2} \mathrm{PO}_{4},$ (d) $\mathrm{KNO}_{2} / \mathrm{HNO}_{2} ?$

Aashna Calidas

Numerade Educator

Problem 18

Which of the following solutions can act as a buffer:
(a) $\mathrm{KCN} / \mathrm{HCN}$,
(b) $\mathrm{Na}_{2} \mathrm{SO}_{4} / \mathrm{NaHSO}_{4}$,
(c) $\mathrm{NH}_{3} / \mathrm{NH}_{4} \mathrm{NO}_{3}$,
(d) NaI/HI?

Aashna Calidas

Numerade Educator

Problem 19

A diprotic acid, $\mathrm{H}_{2} \mathrm{~A},$ has the following ionization constants: $K_{\mathrm{a}_{1}}=1.1 \times 10^{-3}$ and $K_{\mathrm{a}_{2}}=2.5 \times 10^{-6} .$ To make up a buffer solution of $\mathrm{pH}$ 5.80, which combination would you choose: $\operatorname{NaHA} / \mathrm{H}_{2} \mathrm{~A}$ or $\mathrm{Na}_{2} \mathrm{~A} / \mathrm{NaHA} ?$

Aashna Calidas

Numerade Educator

Problem 20

A student is asked to prepare a buffer solution at $\mathrm{pH} 8.60$, using one of the following weak acids: $\mathrm{HA}\left(K_{\mathrm{a}}=2.7 \times\right.$ $\left.10^{-3}\right), \mathrm{HB}\left(K_{\mathrm{a}}=4.4 \times 10^{-6}\right), \mathrm{HC}\left(K_{\mathrm{a}}=2.6 \times 10^{-9}\right)$ Which acid should the student choose? Why?

Aashna Calidas

Numerade Educator

Problem 21

The following diagrams contain one or more of the compounds: $\mathrm{H}_{2} \mathrm{~A}, \mathrm{NaHA},$ and $\mathrm{Na}_{2} \mathrm{~A},$ where $\mathrm{H}_{2} \mathrm{~A}$ is a
weak diprotic acid. (1) Which of the solutions can act as buffer solutions? (2) Which solution is the most effective buffer solution? Water molecules and $\mathrm{Na}^{+}$ ions have been omitted for clarity.

Aashna Calidas

Numerade Educator

Problem 22

The following diagrams represent solutions containing a weak acid $\mathrm{HA}\left(\mathrm{p} K_{\mathrm{a}}=5.0\right)$ and its sodium salt $\mathrm{NaA}$.
(1) Which solution has the lowest pH? Which has the highest pH? (2) How many different species are present after the addition of two $\mathrm{H}^{+}$ ions to solution (a)?
(3) How many different species are present after the addition of four $\mathrm{OH}^{-}$ ions to solution (b)?

Luke Monroe

Numerade Educator

Problem 23

Briefly describe what happens in an acid-base titration.

Sneha Hoysala

Duquesne University

Problem 24

Sketch titration curves for the following acid-base titrations: (a) $\mathrm{HCl}$ versus $\mathrm{NaOH},$ (b) $\mathrm{HCl}$ versus $\mathrm{CH}_{3} \mathrm{NH}_{2},$ (c) $\mathrm{CH}_{3} \mathrm{COOH}$ versus $\mathrm{NaOH}$. In each case, the base is added to the acid in an Erlenmeyer flask. Your graphs should show the $\mathrm{pH}$ on the $y$ axis and the volume of base added on the $x$ axis.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 25

Explain how an acid-base indicator works in a titration. What are the criteria for choosing an indicator for a particular acid-base titration?

Iryna Ivaniuk

Numerade Educator

Problem 26

The amount of indicator used in an acid-base titration must be small. Why?

Aashna Calidas

Numerade Educator

Problem 27

A 0.2688 -g sample of a monoprotic acid neutralizes $16.4 \mathrm{~mL}$ of $0.08133 \mathrm{M}$ KOH solution. Calculate the molar mass of the acid.

Sneha Hoysala

Duquesne University

Problem 28

A $5.00-\mathrm{g}$ quantity of a diprotic acid was dissolved in water and made up to exactly $250 \mathrm{~mL}$. Calculate the molar mass of the acid if $25.0 \mathrm{~mL}$ of this solution required $11.1 \mathrm{~mL}$ of $1.00 \mathrm{M} \mathrm{KOH}$ for neutralization. Assume that both protons of the acid were titrated.

Aashna Calidas

Numerade Educator

Problem 29

In a titration experiment, $12.5 \mathrm{~mL}$ of $0.500 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$ neutralizes $50.0 \mathrm{~mL}$ of $\mathrm{NaOH}$. What is the concentration of the $\mathrm{NaOH}$ solution?

Aashna Calidas

Numerade Educator

Problem 30

In a titration experiment, $20.4 \mathrm{~mL}$ of $0.883 \mathrm{M} \mathrm{HCOOH}$ neutralizes $19.3 \mathrm{~mL}$ of $\mathrm{Ba}(\mathrm{OH})_{2} .$ What is the concentration of the $\mathrm{Ba}(\mathrm{OH})_{2}$ solution?

Aashna Calidas

Numerade Educator

Problem 31

A 0.1276 -g sample of an unknown monoprotic acid was dissolved in $25.0 \mathrm{~mL}$ of water and titrated with a $0.0633 \mathrm{M}$ $\mathrm{NaOH}$ solution. The volume of base required to bring the solution to the equivalence point was $18.4 \mathrm{~mL}$.
(a) Calculate the molar mass of the acid.
(b) After $10.0 \mathrm{~mL}$ of base had been added during the titration, the $\mathrm{pH}$ was determined to be 5.87 . What is the $K_{a}$ of the unknown acid?

David Collins

Numerade Educator

Problem 32

A solution is made by mixing exactly $500 \mathrm{~mL}$ of $0.167 M \mathrm{NaOH}$ with exactly $500 \mathrm{~mL}$ of $0.100 \mathrm{M}$ $\mathrm{CH}_{3} \mathrm{COOH}$. Calculate the equilibrium concentrations of $\mathrm{H}^{+}, \mathrm{CH}_{3} \mathrm{COOH}, \mathrm{CH}_{3} \mathrm{COO}^{-}, \mathrm{OH}^{-},$ and $\mathrm{Na}^{+}$

Luke Monroe

Numerade Educator

Problem 33

Calculate the $\mathrm{pH}$ at the equivalence point for the following titration: $0.20 \mathrm{MHCl}$ versus $0.20 \mathrm{M}$ methylamine $\left(\mathrm{CH}_{3} \mathrm{NH}_{2}\right)$.

Patrick Smith

Numerade Educator

Problem 34

Calculate the $\mathrm{pH}$ at the equivalence point for the following titration: $0.10 \mathrm{M} \mathrm{HCOOH}$ versus $0.10 \mathrm{M} \mathrm{NaOH}$.

Patrick Smith

Numerade Educator

Problem 35

A 25.0 -mL solution of $0.100 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}$ is titrated with a $0.200 \mathrm{M}$ KOH solution. Calculate the $\mathrm{pH}$ after the following additions of the KOH solution: (a) $0.0 \mathrm{~mL}$,
(b) $5.0 \mathrm{~mL}$
(c) $10.0 \mathrm{~mL}$
(d) $12.5 \mathrm{~mL}$,
(e) $15.0 \mathrm{~mL}$.

Iryna Ivaniuk

Numerade Educator

Problem 36

A $10.0-\mathrm{mL}$ solution of $0.300 \mathrm{M} \mathrm{NH}_{3}$ is titrated with a $0.100 M \mathrm{HCl}$ solution. Calculate the $\mathrm{pH}$ after the following additions of the HCl solution:
(a) $0.0 \mathrm{~mL}$
(b) $10.0 \mathrm{~mL}$
(c) $20.0 \mathrm{~mL}$,
(d) $30.0 \mathrm{~mL}$
(e) $40.0 \mathrm{~mL}$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 37

Referring to Table 17.3 , specify which indicator or indicators you would use for the following titrations:
(a) HCOOH versus $\mathrm{NaOH}$,
(b) HCl versus KOH,
(c) $\mathrm{HNO}_{3}$ versus $\mathrm{CH}_{3} \mathrm{NH}_{2}$.

Prashant Bana

Numerade Educator

Problem 38

A student carried out an acid-base titration by adding $\mathrm{NaOH}$ solution from a burette to an Erlenmeyer flask containing an HCl solution and using phenolphthalein as the indicator. At the equivalence point, she observed a faint reddish-pink color. However, after a few minutes, the solution gradually turned colorless. What do you suppose happened?

Prashant Bana

Numerade Educator

Problem 39

The ionization constant $K_{\mathrm{a}}$ of an indicator $\mathrm{HIn}$ is $1.0 \times 10^{-6}$. The color of the nonionized form is red and that of the ionized form is yellow. What is the color of this indicator in a solution whose $\mathrm{pH}$ is $4.00 ?$

Aashna Calidas

Numerade Educator

Problem 40

The $K_{\mathrm{a}}$ of a certain indicator is $2.0 \times 10^{-6} .$ The color of HIn is green and that of $\mathrm{In}^{-}$ is red. A few drops of the indicator are added to an $\mathrm{HCl}$ solution, which is then titrated against an $\mathrm{NaOH}$ solution. At what $\mathrm{pH}$ will the indicator change color?

Prashant Bana

Numerade Educator

Problem 41

The following diagrams represent solutions at various stages in the titration of a weak base $\mathrm{B}$ (such as $\mathrm{NH}_{3}$ ) with $\mathrm{HCl}$. Identify the solution that corresponds to
(1) the initial stage before the addition of $\mathrm{HCl}$, (2) halfway to the equivalence point, ( 3 ) the equivalence point, (4) beyond the equivalence point. Is the pH greater than, less than, or equal to 7 at the equivalence point? Water and $\mathrm{Cl}^{-}$ ions have been omitted for clarity.

Prashant Bana

Numerade Educator

Problem 42

The following diagrams represent solutions at various stages in the titration of a weak acid HA with $\mathrm{NaOH}$. Identify the solution that corresponds to (1) the initial stage before the addition of $\mathrm{NaOH},$ ( 2 ) half way to the equivalence point, (3) the equivalence point, (4) beyond the equivalence point. Is the $\mathrm{pH}$ greater than, less than, or equal to 7 at the equivalence point? Water and $\mathrm{Na}^{+}$ ions have been omitted for clarity.

Prashant Bana

Numerade Educator

Problem 43

Use BaSO $_{4}$ to distinguish between the terms solubility and solubility product.

Aashna Calidas

Numerade Educator

Problem 44

Why do we usually not quote the $K_{\mathrm{sp}}$ values for soluble ionic compounds?

Aashna Calidas

Numerade Educator

Problem 45

Write balanced equations and solubility product expressions for the solubility equilibria of the following compounds:
(a) $\mathrm{CuBr}$
(b) $\mathrm{ZnC}_{2} \mathrm{O}_{4},$ (c) $\mathrm{Ag}_{2} \mathrm{CrO}_{4}$,
(d) $\mathrm{Hg}_{2} \mathrm{Cl}_{2},$ (e) $\mathrm{AuCl}_{3}$, (f) $\mathrm{Mn}_{3}\left(\mathrm{PO}_{4}\right)_{2}$.

Prashant Bana

Numerade Educator

Problem 46

Write the solubility product expression for the ionic compound $\mathrm{A}_{x} \mathrm{~B}_{y}$

Aashna Calidas

Numerade Educator

Problem 47

How can we predict whether a precipitate will form when two solutions are mixed?

Aashna Calidas

Numerade Educator

Problem 48

Silver chloride has a larger $K_{\mathrm{sp}}$ than silver carbonate (see Table 17.4). Does this mean that $\mathrm{AgCl}$ also has a larger molar solubility than $\mathrm{Ag}_{2} \mathrm{CO}_{3} ?$

Prashant Bana

Numerade Educator

Problem 49

Calculate the concentration of the following ions: (a) $\left[\mathrm{I}^{-}\right]$ in a saturated solution of $\mathrm{AgI}$, (b) $\left[\mathrm{Al}^{3+}\right]$ in $\left[\mathrm{Al}(\mathrm{OH})_{3}\right]$ solution with $\left[\mathrm{OH}^{-}\right]=2.9 \times 10^{-9} \mathrm{M}$

Aashna Calidas

Numerade Educator

Problem 50

From the solubility data given, calculate the solubility products for the following compounds:
(a) $\operatorname{SrF}_{2}, 7.3 \times$ $10^{-2} \mathrm{~g} / \mathrm{L},(\mathrm{b}) \mathrm{Ag}_{3} \mathrm{PO}_{4}, 6.7 \times 10^{-3} \mathrm{~g} / \mathrm{L}$

Aadit Sharma

Numerade Educator

Problem 51

The molar solubility of $\mathrm{MnCO}_{3}$ is $4.2 \times 10^{-6} \mathrm{M}$. What is $K_{\mathrm{sp}}$ for this compound?

Aashna Calidas

Numerade Educator

Problem 52

The solubility of an ionic compound $\mathrm{MX}$ (molar mass = $346 \mathrm{~g}$ ) is $4.63 \times 10^{-3} \mathrm{~g} / \mathrm{L} .$ What is $K_{\mathrm{ep}}$ for this compound?

Aashna Calidas

Numerade Educator

Problem 53

The solubility of an ionic compound $\mathrm{M}_{2} \mathrm{X}_{3}$ (molar mass $=288 \mathrm{~g}$ ) is $3.6 \times 10^{-17} \mathrm{~g} / \mathrm{L}$. What is $K_{\mathrm{sp}}$ for this compound?

Aashna Calidas

Numerade Educator

Problem 54

Using data from Table $17.4,$ calculate the molar solubility of $\mathrm{CaF}_{2}$.

Aashna Calidas

Numerade Educator

Problem 55

What is the $\mathrm{pH}$ of a saturated zinc hydroxide solution?

Aashna Calidas

Numerade Educator

Problem 56

The $\mathrm{pH}$ of a saturated solution of a metal hydroxide $\mathrm{MOH}$ is $9.68 .$ Calculate the $K_{\mathrm{sp}}$ for this compound.

Aashna Calidas

Numerade Educator

Problem 57

If $20.0 \mathrm{~mL}$ of $0.10 \mathrm{M} \mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}$ is added to $50.0 \mathrm{~mL}$ of $0.10 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3},$ will $\mathrm{BaCO}_{3}$ precipitate?

Aashna Calidas

Numerade Educator

Problem 58

A volume of $75 \mathrm{~mL}$ of $0.060 \mathrm{M} \mathrm{NaF}$ is mixed with $25 \mathrm{~mL}$ of $0.15 M \mathrm{Sr}\left(\mathrm{NO}_{3}\right)_{2}$. Calculate the concentrations in the final solution of $\mathrm{NO}_{3}^{-}, \mathrm{Na}^{+}, \mathrm{Sr}^{2+},$ and $\mathrm{F}^{-} \cdot\left(K_{\mathrm{sp}}\right.$ for $\left.\mathrm{SrF}_{2}=2.0 \times 10^{-10} .\right)$

Patrick Smith

Numerade Educator

Problem 59

How does the common ion effect influence solubility equilibria? Use Le Châtelier's principle to explain the decrease in solubility of $\mathrm{CaCO}_{3}$ in an $\mathrm{Na}_{2} \mathrm{CO}_{3}$ solution.

Aashna Calidas

Numerade Educator

Problem 60

The molar solubility of $\mathrm{AgCl}$ in $6.5 \times 10^{-3} \mathrm{M} \mathrm{AgNO}_{3}$ is $2.5 \times 10^{-8} M .$ In deriving $K_{\mathrm{sp}}$ from these data, which of the following assumptions are reasonable? (a) $K_{\mathrm{sp}}$ is the same as solubility. (b) $K_{\mathrm{sp}}$ of $\mathrm{AgCl}$ is the same in $6.5 \times$ $10^{-3} M \mathrm{AgNO}_{3}$ as in pure water. (c) Solubility of $\mathrm{AgCl}$ is independent of the concentration of $\mathrm{AgNO}_{3}$. (d) $\left[\mathrm{Ag}^{+}\right]$ in solution does not change significantly upon the addition of $\mathrm{AgCl}$ to $6.5 \times 10^{-3} \mathrm{M} \mathrm{AgNO}_{3}$. (e) $\left[\mathrm{Ag}^{+}\right]$ in solution after the addition of $\mathrm{AgCl}$ to $6.5 \times 10^{-3} \mathrm{M}$ $\mathrm{AgNO}_{3}$ is the same as it would be in pure water.

Prashant Bana

Numerade Educator

Problem 61

Give an example to illustrate the general effect of complex ion formation on solubility.

Aashna Calidas

Numerade Educator

Problem 62

How many grams of $\mathrm{CaCO}_{3}$ will dissolve in $3.0 \times 10^{2} \mathrm{~mL}$ of $0.050 \mathrm{M} \mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2} ?$

Iryna Ivaniuk

Numerade Educator

Problem 63

The solubility product of $\mathrm{PbBr}_{2}$ is $8.9 \times 10^{-6} .$ Determine the molar solubility in (a) pure water, (b) $0.20 \mathrm{M}$ KBr solution, and (c) $0.20 M \mathrm{~Pb}\left(\mathrm{NO}_{3}\right)_{2}$ solution.

Aadit Sharma

Numerade Educator

Problem 64

Calculate the molar solubility of $\mathrm{AgCl}$ in a $1.00-\mathrm{L}$ solution containing $10.0 \mathrm{~g}$ of dissolved $\mathrm{CaCl}_{2}$.

Iryna Ivaniuk

Numerade Educator

Problem 65

Calculate the molar solubility of $\mathrm{BaSO}_{4}$ in (a) water and (b) a solution containing $1.0 M \mathrm{SO}_{4}^{2-}$ ions.

Satpal Satpal

Numerade Educator

Problem 66

Which of the following ionic compounds will be more soluble in acid solution than in water:
(a) $\mathrm{BaSO}_{4},$
(b) $\mathrm{PbCl}_{2}$
(c) $\mathrm{Fe}(\mathrm{OH})_{3}$
(d) $\mathrm{CaCO}_{3}$ ?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 67

Which of the following will be more soluble in acid solution than in pure water:
(a) $\mathrm{CuI}$,
(b) $\mathrm{Ag}_{2} \mathrm{SO}_{4}$,
(c) $\mathrm{Zn}(\mathrm{OH})_{2}$
(d) $\mathrm{BaC}_{2} \mathrm{O}_{4}$
(e) $\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2} ?$

Ronald Prasad

Numerade Educator

Problem 68

Compare the molar solubility of $\mathrm{Mg}(\mathrm{OH})_{2}$ in water and in a solution buffered at a pH of 9.0 .

Aashna Calidas

Numerade Educator

Problem 69

Calculate the molar solubility of $\mathrm{Fe}(\mathrm{OH})_{2}$ in a solution buffered at (a) a pH of 8.00 and (b) a pH of 10.00 .

Aadit Sharma

Numerade Educator

Problem 70

The solubility product of $\mathrm{Mg}(\mathrm{OH})_{2}$ is $1.2 \times 10^{-11} .$ What minimum $\mathrm{OH}^{-}$ concentration must be attained (e.g., by adding $\mathrm{NaOH}$ ) to decrease the $\mathrm{Mg}$ concentration in a solution of $\mathrm{Mg}\left(\mathrm{NO}_{3}\right)_{2}$ to less than $1.0 \times 10^{-10} \mathrm{M} ?$

Iryna Ivaniuk

Numerade Educator

Problem 71

Calculate whether or not a precipitate will form if $2.00 \mathrm{~mL}$ of $0.60 \mathrm{M} \mathrm{NH}_{3}$ is added to $1.0 \mathrm{~L}$ of $1.0 \times 10^{-3} \mathrm{M} \mathrm{FeSO}_{4}$

Aadit Sharma

Numerade Educator

Problem 72

If $2.50 \mathrm{~g}$ of $\mathrm{CuSO}_{4}$ is dissolved in $9.0 \times 10^{2} \mathrm{~mL}$ of $0.30 \mathrm{M} \mathrm{NH}_{3},$ what are the concentrations of $\mathrm{Cu}^{2+}$ $\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}^{2+},$ and $\mathrm{NH}_{3}$ at equilibrium?

Iryna Ivaniuk

Numerade Educator

Problem 73

Calculate the concentrations of $\mathrm{Cd}^{2+}, \mathrm{Cd}(\mathrm{CN})_{4}^{2-},$ and $\mathrm{CN}^{-}$ at equilibrium when $0.50 \mathrm{~g}$ of $\mathrm{Cd}\left(\mathrm{NO}_{3}\right)_{2}$ dissolves in $5.0 \times 10^{2} \mathrm{~mL}$ of $0.50 \mathrm{M} \mathrm{NaCN}$.

Manik Pulyani

Numerade Educator

Problem 74

If $\mathrm{NaOH}$ is added to $0.010 \mathrm{M} \mathrm{Al}^{3+},$ which will be the predominant species at equilibrium: $\mathrm{Al}(\mathrm{OH})_{3}$ or $\mathrm{Al}(\mathrm{OH})_{4}^{-} ?$ The $\mathrm{pH}$ of the solution is $14.00 .\left[K_{\mathrm{f}}\right.$ for $\left.\mathrm{Al}(\mathrm{OH})_{4}^{-}=2.0 \times 10^{33} .\right]$

Iryna Ivaniuk

Numerade Educator

Problem 75

Calculate the molar solubility of AgI in a $1.0 M \mathrm{NH}_{3}$ solution.

Aadit Sharma

Numerade Educator

Problem 76

Both $\mathrm{Ag}^{+}$ and $\mathrm{Zn}^{2+}$ form complex ions with $\mathrm{NH}_{3}$. Write balanced equations for the reactions. However, $\mathrm{Zn}(\mathrm{OH})_{2}$ is soluble in $6 M \mathrm{NaOH},$ and $\mathrm{AgOH}$ is not. Explain.

Iryna Ivaniuk

Numerade Educator

Problem 77

Explain, with balanced ionic equations, why (a) $\mathrm{CuI}_{2}$ dissolves in ammonia solution, (b) AgBr dissolves in NaCN solution, and (c) $\mathrm{HgCl}_{2}$ dissolves in KCl solution.

Prashant Bana

Numerade Educator

Problem 78

Outline the general procedure of qualitative analysis.

Iryna Ivaniuk

Numerade Educator

Problem 79

Give two examples of metal ions in each group ( 1 through 5 ) in the qualitative analysis scheme.

Prashant Bana

Numerade Educator

Problem 80

Solid NaI is slowly added to a solution that is $0.010 M$ in $\mathrm{Cu}^{+}$ and $0.010 \mathrm{M}$ in $\mathrm{Ag}^{+}$. (a) Which compound will begin to precipitate first? (b) Calculate $\left[\mathrm{Ag}^{+}\right]$ when CuI just begins to precipitate. (c) What percent of $\mathrm{Ag}^{+}$ remains in solution at this point?

Aadit Sharma

Numerade Educator

Problem 81

Find the approximate $\mathrm{pH}$ range suitable for the separation of $\mathrm{Fe}^{3+}$ and $\mathrm{Zn}^{2+}$ ions by precipitation of $\mathrm{Fe}(\mathrm{OH})_{3}$ from a solution that is initially $0.010 M$ in both $\mathrm{Fe}^{3+}$ and $\mathrm{Zn}^{2+}$

Manik Pulyani

Numerade Educator

Problem 82

In a group 1 analysis, a student obtained a precipitate containing both $\mathrm{AgCl}$ and $\mathrm{PbCl}_{2}$. Suggest one reagent that would enable the student to separate $\operatorname{AgCl}(s)$ from $\mathrm{PbCl}_{2}(s)$

Iryna Ivaniuk

Numerade Educator

Problem 83

In a group 1 analysis, a student adds $\mathrm{HCl}$ acid to the unknown solution to make $\left[\mathrm{Cl}^{-}\right]=0.15 M .$ Some $\mathrm{PbCl}_{2}$ precipitates. Calculate the concentration of $\mathrm{Pb}^{2+}$ remaining in solution.

Prashant Bana

Numerade Educator

Problem 84

Both $\mathrm{KCl}$ and $\mathrm{NH}_{4} \mathrm{Cl}$ are white solids. Suggest one reagent that would enable you to distinguish between these two compounds.

Iryna Ivaniuk

Numerade Educator

Problem 85

Describe a simple test that would allow you to distinguish between $\operatorname{AgNO}_{3}(s)$ and $\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}(s) .$

Prashant Bana

Numerade Educator

Problem 86

The buffer range is defined by the equation $\mathrm{pH}=\mathrm{p} K_{\mathrm{a}} \pm 1$ Calculate the range of the ratio [conjugate base $] /[$ acid $]$ that corresponds to this equation.

Prashant Bana

Numerade Educator

Problem 87

The $\mathrm{p} K_{\mathrm{a}}$ of the indicator methyl orange is 3.46 . Over what $\mathrm{pH}$ range does this indicator change from 90 percent HIn to 90 percent $\operatorname{In}^{-} ?$

Prashant Bana

Numerade Educator

Problem 88

Sketch the titration curve of a weak acid with a strong base like the one shown in Figure $17.4 .$ On your graph, indicate the volume of base used at the equivalence point and also at the half-equivalence point, that is, the point at which half of the acid has been neutralized. Explain how the measured $\mathrm{pH}$ at the half-equivalence point can be used to determine $K_{\mathrm{a}}$ of the acid.

Prashant Bana

Numerade Educator

Problem 89

A 200-mL volume of $\mathrm{NaOH}$ solution was added to $400 \mathrm{~mL}$ of a $2.00 \mathrm{M} \mathrm{HNO}_{2}$ solution. The $\mathrm{pH}$ of the mixed solution was 1.50 units greater than that of the original acid solution. Calculate the molarity of the $\mathrm{NaOH}$ solution.

Manik Pulyani

Numerade Educator

Problem 90

The $\mathrm{p} K_{\mathrm{a}}$ of butyric acid (HBut) is $4.7 .$ Calculate $K_{\mathrm{b}}$ for the butyrate ion (But $^{-}$ ).

Prashant Bana

Numerade Educator

Problem 91

A solution is made by mixing exactly $500 \mathrm{~mL}$ of $0.167 \mathrm{M}$ NaOH with exactly $500 \mathrm{~mL} 0.100 \mathrm{M}$ HCOOH. Calculate the equilibrium concentrations of $\mathrm{H}_{3} \mathrm{O}^{+}$ $\mathrm{HCOOH}, \mathrm{HCOO}^{-}, \mathrm{OH}^{-},$ and $\mathrm{Na}^{+}$

Prashant Bana

Numerade Educator

Problem 92

The titration curve shown here represents the titration of a weak diprotic acid $\left(\mathrm{H}_{2} \mathrm{~A}\right)$ versus $\mathrm{NaOH}$.
(a) Label the major species present at the marked points.
(b) Estimate the $\mathrm{p} K_{\mathrm{a}_{1}}$ and $\mathrm{p} K_{\mathrm{a}_{2}}$ values of the acid. Assume that any salt hydrolysis is negligible.

Aadit Sharma

Numerade Educator

Problem 93

$\mathrm{Cd}(\mathrm{OH})_{2}$ is an insoluble compound. It dissolves in excess $\mathrm{NaOH}$ in solution. Write a balanced ionic equation for this reaction. What type of reaction is this?

Iryna Ivaniuk

Numerade Educator

Problem 94

A student mixes $50.0 \mathrm{~mL}$ of $1.00 \mathrm{M} \mathrm{Ba}(\mathrm{OH})_{2}$ with $86.4 \mathrm{~mL}$ of $0.494 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4} .$ Calculate the mass of $\mathrm{BaSO}_{4}$ formed and the $\mathrm{pH}$ of the mixed solution.

Aadit Sharma

Numerade Educator

Problem 95

For which of the following reactions is the equilibrium constant called a solubility product?
(a) $\mathrm{Zn}(\mathrm{OH})_{2}(s)+2 \mathrm{OH}^{-}(a q) \rightleftharpoons \mathrm{Zn}(\mathrm{OH})_{4}^{2-}(a q)$
(b) $3 \mathrm{Ca}^{2+}(a q)+2 \mathrm{PO}_{4}^{3-}(a q) \rightleftharpoons \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}(s)$
(c) $\mathrm{CaCO}_{3}(s)+2 \mathrm{H}^{+}(a q) \rightleftarrows$ $\mathrm{Ca}^{2+}(a q)+\mathrm{H}_{2} \mathrm{O}(l)+\mathrm{CO}_{2}(g)$
(d) $\mathrm{PbI}_{2}(s) \rightleftarrows \mathrm{Pb}^{2+}(a q)+2 \mathrm{I}^{-}(a q)$

Iryna Ivaniuk

Numerade Educator

Problem 96

Water containing $\mathrm{Ca}^{2+}$ and $\mathrm{Mg}^{2+}$ ions is called hard water and is unsuitable for some household and industrial use because these ions react with soap to form insoluble salts, or curds. One way to remove the $\mathrm{Ca}^{2+}$ ions from hard water is by adding washing soda $\left(\mathrm{Na}_{2} \mathrm{CO}_{3} \cdot 10 \mathrm{H}_{2} \mathrm{O}\right)$
(a) The molar solubility of $\mathrm{CaCO}_{3}$ is $9.3 \times 10^{-5} \mathrm{M}$. What is its molar solubility in a $0.050 \mathrm{M} \mathrm{Na}_{2} \mathrm{CO}_{3}$ solution?
(b) Why are $\mathrm{Mg}^{2+}$ ions not removed by this procedure?
(c) The $\mathrm{Mg}^{2+}$ ions are removed as $\mathrm{Mg}(\mathrm{OH})_{2}$ by adding slaked lime $\left[\mathrm{Ca}(\mathrm{OH})_{2}\right]$ to the water to produce a saturated solution. Calculate the $\mathrm{pH}$ of a saturated $\mathrm{Ca}(\mathrm{OH})_{2}$ solution. (d) What is the concentration of $\mathrm{Mg}^{2+}$ ions at this $\mathrm{pH} ?$ (e) In general, which ion $\left(\mathrm{Ca}^{2+}\right.$ or $\mathrm{Mg}^{2+}$ ) would you remove first? Why?

Manik Pulyani

Numerade Educator

Problem 97

Equal volumes of $0.12 M \mathrm{AgNO}_{3}$ and $0.14 \mathrm{M} \mathrm{ZnCl}_{2}$ solution are mixed. Calculate the equilibrium concentrations of $\mathrm{Ag}^{+}, \mathrm{Cl}^{-}, \mathrm{Zn}^{2+},$ and $\mathrm{NO}_{3}^{-}$

Iryna Ivaniuk

Numerade Educator

Problem 98

Find the approximate $\mathrm{pH}$ range suitable for separating $\mathrm{Mg}^{2+}$ and $\mathrm{Zn}^{2+}$ by the precipitation of $\mathrm{Zn}(\mathrm{OH})_{2}$ from a solution that is initially $0.010 M$ in $\mathrm{Mg}^{2+}$ and $\mathrm{Zn}^{2+}$

Iryna Ivaniuk

Numerade Educator

Problem 99

Calculate the solubility (in $\mathrm{g} / \mathrm{L}$ ) of $\mathrm{Ag}_{2} \mathrm{CO}_{3}$.

Aadit Sharma

Numerade Educator

Problem 100

A volume of $25.0 \mathrm{~mL}$ of $0.100 \mathrm{M} \mathrm{HCl}$ is titrated against a $0.100 \mathrm{M} \mathrm{CH}_{3} \mathrm{NH}_{2}$ solution added to it from a burette. Calculate the $\mathrm{pH}$ values of the solution after (a) $10.0 \mathrm{~mL}$ of $\mathrm{CH}_{3} \mathrm{NH}_{2}$ solution has been added, (b) $25.0 \mathrm{~mL}$ of $\mathrm{CH}_{3} \mathrm{NH}_{2}$ solution has been added, (c) $35.0 \mathrm{~mL}$ of $\mathrm{CH}_{3} \mathrm{NH}_{2}$ solution has been added.

Manik Pulyani

Numerade Educator

Problem 101

The molar solubility of $\mathrm{Pb}\left(\mathrm{IO}_{3}\right)_{2}$ in a $0.10 \mathrm{M} \mathrm{NaIO}_{3}$ solution is $2.4 \times 10^{-11} \mathrm{~mol} / \mathrm{L} .$ What is $K_{\mathrm{sp}}$ for $\mathrm{Pb}\left(\mathrm{IO}_{3}\right)_{2} ?$

Iryna Ivaniuk

Numerade Educator

Problem 102

When a KI solution was added to a solution of mercury(II) chloride, a precipitate [mercury(II) iodide] formed. A student plotted the mass of the precipitate versus the volume of the KI solution added and obtained the following graph. Explain the shape of the graph.

Prashant Bana

Numerade Educator

Problem 103

Which of the following compounds, when added to water, will increase the solubility of CdS:
(a) LiNO $_{3}$,
(b) $\mathrm{Na}_{2} \mathrm{SO}_{4},$ (c) $\mathrm{KCN}$,
(d) $\mathrm{NaClO}_{3} ?$

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 104

The $\mathrm{p} K_{\mathrm{a}}$ of phenolphthalein is 9.10 . Over what $\mathrm{pH}$ range does this indicator change from 95 percent HIn to 95 percent $\operatorname{In}^{-1} ?$

Prashant Bana

Numerade Educator

Problem 105

Solid NaBr is slowly added to a solution that is $0.010 \mathrm{M}$ in $\mathrm{Cu}^{+}$ and $0.010 \mathrm{M}$ in $\mathrm{Ag}^{+}$. (a) Which compound will begin to precipitate first? (b) Calculate $\left[\mathrm{Ag}^{+}\right]$ when CuBr just begins to precipitate. (c) What percent of Ag $^{+}$ remains in solution at this point?

Iryna Ivaniuk

Numerade Educator

Problem 106

Cacodylic acid is (CH $_{3}$ ) $_{2}$ AsO $_{2}$ H. Its ionization constant is $6.4 \times 10^{-7}$ (a) Calculate the pH of $50.0 \mathrm{~mL}$ of a $0.10-M$ solution of the acid. (b) Calculate the $\mathrm{pH}$ of $25.0 \mathrm{~mL}$ of $0.15 M\left(\mathrm{CH}_{3}\right)_{2} \mathrm{AsO}_{2} \mathrm{Na} .$ (c) Mix the solutions in parts (a) and (b). Calculate the pH of the resulting solution.

Kratika Bhadauria

Kratika Bhadauria

Numerade Educator

Problem 107

What reagents would you employ to separate the following pairs of ions in solution: (a) $\mathrm{Na}^{+}$ and $\mathrm{Ba}^{2+}$ (b) $\mathrm{K}^{+}$ and $\mathrm{Pb}^{2+},$ (c) $\mathrm{Zn}^{2+}$ and $\mathrm{Hg}^{2+} ?$

Prashant Bana

Numerade Educator

Problem 108

Look up the $K_{\mathrm{sp}}$ values for $\mathrm{BaSO}_{4}$ and $\mathrm{Sr} \mathrm{SO}_{4}$ in Table 17.4 . Calculate the concentrations of $\mathrm{Ba}^{2+}, \mathrm{Sr}^{2+},$ and $\mathrm{SO}_{4}^{2-}$ in a solution that is saturated with both compounds.

Prashant Bana

Numerade Educator

Problem 109

In principle, amphoteric oxides, such as $\mathrm{Al}_{2} \mathrm{O}_{3}$ and $\mathrm{BeO}$ can be used to prepare buffer solutions because they possess both acidic and basic properties (see Section 16.11 ). Explain why these compounds are of little practical use as buffer components.

Prashant Bana

Numerade Educator

Problem 110

$\mathrm{CaSO}_{4}\left(K_{\mathrm{sp}}=2.4 \times 10^{-5}\right)$ has a larger $K_{\mathrm{sp}}$ value than that of $\mathrm{Ag}_{2} \mathrm{SO}_{4}\left(K_{\mathrm{sp}}=1.4 \times 10^{-5}\right) .$ Does it necessarily follow that $\mathrm{CaSO}_{4}$ also has greater solubility $(\mathrm{g} / \mathrm{L}) ?$ Explain.

Tom Comey

Numerade Educator

Problem 111

Describe how you would prepare a $1-\mathrm{L} 0.20 \mathrm{M}$ $\mathrm{CH}_{3} \mathrm{COONa} / 0.20 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}$ buffer system by (a) mixing a solution of $\mathrm{CH}_{3} \mathrm{COOH}$ with a solution of $\mathrm{CH}_{3} \mathrm{COONa},$ (b) mixing a solution of $\mathrm{CH}_{3} \mathrm{COOH}$ with a solution of $\mathrm{NaOH}$, and (c) mixing a solution of $\mathrm{CH}_{3} \mathrm{COONa}$ with a solution of $\mathrm{HCl}$.

Iryna Ivaniuk

Numerade Educator

Problem 112

Phenolphthalein is the common indicator for the titration of a strong acid with a strong base. (a) If the $\mathrm{p} K_{\mathrm{a}}$ of phenolphthalein is 9.10 , what is the ratio of the nonionized form of the indicator (colorless) to the ionized form (reddish pink) at pH $8.00 ?$ (b) If 2 drops of $0.060 \mathrm{M}$ phenolphthalein are used in a titration involving a $50.0-\mathrm{mL}$ volume, what is the concentration of the ionized form at $\mathrm{pH} 8.00 ?$ (Assume that 1 drop $=$ $0.050 \mathrm{~mL} .)$

Manik Pulyani

Numerade Educator

Problem 113

Of the reactions depicted, which best represents (a) what occurs when strong acid is added to a buffer solution, and (b) what occurs when strong base is added to a buffer solution?

David Collins

Numerade Educator

Problem 114

The molar mass of a certain metal carbonate, $\mathrm{MCO}_{3}$, can be determined by adding an excess of $\mathrm{HCl}$ acid to react with all the carbonate and then "back-titrating" the remaining acid with $\mathrm{NaOH}$. (a) Write an equation for these reactions. (b) In a certain experiment, $20.00 \mathrm{~mL}$ of $0.0800 M \mathrm{HCl}$ was added to a $0.1022-\mathrm{g}$ sample of $\mathrm{MCO}_{3}$. The excess HCl required $5.64 \mathrm{~mL}$ of $0.1000 \mathrm{M}$ $\mathrm{NaOH}$ for neutralization. Calculate the molar mass of the carbonate and identify $\mathrm{M}$.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 115

Consider the ionization of the following acid-base indicator:
$$
\mathrm{HIn}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons \mathrm{H}_{3} \mathrm{O}^{+}(a q)+\mathrm{In}^{-}(a q)
$$
The indicator changes color according to the ratios of the concentrations of the acid to its conjugate base. When [HIn]/[In'] $\geq 10,$ color of acid (HIn) predominates. When [HIn] $/\left[\operatorname{In}^{-}\right] \leq 0.1,$ color of conjugate base $\left(\mathrm{In}^{-}\right)$ predominates. Show that the $\mathrm{pH}$ range over which the indicator changes from the acid color to the base color is $\mathrm{pH}=\mathrm{p} K_{\mathrm{a}} \pm 1,$ where $K_{\mathrm{a}}$ is the ionization constant of the acid HIn.

Prashant Bana

Numerade Educator

Problem 116

One way to distinguish a buffer solution from an acid solution is to dilute both. (a) Consider a buffer solution made of $0.500 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}$ and $0.500 \mathrm{M} \mathrm{CH}_{3} \mathrm{COONa} .$ Calculate its $\mathrm{pH}$ before and after it has been diluted 10-fold. (b) Compare the result in part (a) with the pH of a $0.500 \mathrm{M} \mathrm{CH}_{3} \mathrm{COOH}$ solution before and after it has been diluted 10-fold.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 117

(a) Referring to Figure $17.4,$ describe how you would determine the $\mathrm{p} K_{\mathrm{b}}$ of the base. (b) Derive an analogous Henderson-Hasselbalch equation relating $\mathrm{pOH}$ to $\mathrm{p} K_{\mathrm{b}}$ of a weak base $\mathrm{B}$ and its conjugate acid $\mathrm{HB}^{+} .$ Sketch a titration curve showing the variation of the $\mathrm{pOH}$ of the base solution versus the volume of a strong acid added from a burette. Describe how you would determine the $\mathrm{p} K_{\mathrm{b}}$ from this curve.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 118

$\mathrm{AgNO}_{3}$ is added slowly to a solution that contains $0.1 \mathrm{M}$ each of $\mathrm{Br}^{-}, \mathrm{CO}_{3}^{2-},$ and $\mathrm{SO}_{4}^{2-}$ ions. What compound will precipitate first and what compound will precipitate last?

Raghvendra Singh

Raghvendra Singh

Numerade Educator

Problem 119

The following diagrams represent solutions of $\mathrm{MX}$, which may also contain one or both of the soluble salts, $\mathrm{MNO}_{3}$ and $\mathrm{NaX} .\left(\mathrm{Na}^{+}\right.$ and $\mathrm{NO}_{3}-$ ions are not shown. $)$ If (a) represents a saturated solution of MX, classify each of the other solutions as unsaturated, saturated, or supersaturated.

David Collins

Numerade Educator

Problem 120

A 2.0-L kettle contains $116 \mathrm{~g}$ of boiler scale $\left(\mathrm{CaCO}_{3}\right)$. How many times would the kettle have to be completely filled with distilled water to remove all the deposit at $25^{\circ} \mathrm{C} ?$

Prashant Bana

Numerade Educator

Problem 121

Radiochemical techniques are useful in estimating the solubility product of many compounds. In one experiment, $50.0 \mathrm{~mL}$ of a $0.010 \mathrm{M} \mathrm{AgNO}_{3}$ solution containing a silver isotope with a radioactivity of 74,025 counts per min per $\mathrm{mL}$ was mixed with $100 \mathrm{~mL}$ of a $0.030 \mathrm{M} \mathrm{NaIO}_{3}$ solution. The mixed solution was diluted to $500 \mathrm{~mL}$ and filtered to remove all the $\mathrm{AgIO}_{3}$ precipitate. The remaining solution was found to have a radioactivity of 44.4 counts per min per $\mathrm{mL}$. What is the $K_{\mathrm{sp}}$ of $\mathrm{AgIO}_{3} ?$

Iryna Ivaniuk

Numerade Educator

Problem 122

One of the most common antibiotics is penicillin $\mathrm{G}$ (benzylpenicillinic acid), which has the following structure:
It is a weak monoprotic acid:
$$
\mathrm{HP} \rightleftarrows \mathrm{H}^{+}+\mathrm{P}^{-} \quad K_{\mathrm{a}}=1.64 \times 10^{-3}
$$
where HP denotes the parent acid and $\mathrm{P}^{-}$ the conjugate base. Penicillin G is produced by growing molds in fermentation tanks at $25^{\circ} \mathrm{C}$ and a pH range of 4.5 to $5.0 .$ The crude form of this antibiotic is obtained by extracting the fermentation broth with an organic solvent in which the acid is soluble. (a) Identify the acidic hydrogen atom.
(b) In one stage of purification, the organic extract of the crude penicillin $\mathrm{G}$ is treated with a buffer solution at $\mathrm{pH}=6.50 .$ What is the ratio of the conjugate base of penicillin G to the acid at this pH? Would you expect the conjugate base to be more soluble in water than the acid?
(c) Penicillin G is not suitable for oral administration, but the sodium salt (NaP) is because it is soluble. Calculate the $\mathrm{pH}$ of a $0.12 \mathrm{M}$ NaP solution formed when a tablet containing the salt is dissolved in a glass of water.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 123

Barium is a toxic substance that can seriously impair heart function. For an X ray of the gastrointestinal tract, a patient drinks an aqueous suspension of $20 \mathrm{~g} \mathrm{BaSO}_{4}$. If this substance were to equilibrate with the $5.0 \mathrm{~L}$ of the blood in the patient's body, what would be $\left[\mathrm{Ba}^{2+}\right] ?$ For a good estimate, we may assume that the $K_{\mathrm{sp}}$ of $\mathrm{BaSO}_{4}$ at body temperature is the same as at $25^{\circ} \mathrm{C}$. Why is $\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}$ not chosen for this procedure?

Narayan Hari

Numerade Educator

Problem 124

Tris [tris(hydroxymethyl)aminomethane] is a common buffer for studying biological systems: (a) Calculate the $\mathrm{pH}$ of the tris buffer after mixing $15.0 \mathrm{~mL}$ of $0.10 \mathrm{M}$ HCl solution with $25.0 \mathrm{~mL}$ of $0.10 \mathrm{M}$ tris. (b) This buffer was used to study an enzyme-catalyzed reaction. As a result of the reaction, 0.00015 mole of $\mathrm{H}^{+}$ was consumed. What is the $\mathrm{pH}$ of the buffer at the end of the reaction? (c) What would be the final pH if no buffer were present?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 125

Calcium oxalate is a major component of kidney stones. Predict whether the formation of kidney stones can be minimized by increasing or decreasing the $\mathrm{pH}$ of the fluid present in the kidney. The pH of normal kidney fluid is about 8.2 . [The first and second acid ionization constants of oxalic acid $\left(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}\right)$ are $6.5 \times 10^{-2}$ and $6.1 \times 10^{-5},$ respectively. The solubility product of calcium oxalate is $\left.3.0 \times 10^{-9} .\right]$

Prashant Bana

Numerade Educator

Problem 126

Histidine is one of the 20 amino acids found in proteins. Shown here is a fully protonated histidine molecule, where the numbers denote the $\mathrm{p} K_{\mathrm{a}}$ values of the acidic groups:
(a) Show stepwise ionization of histidine in solution. (Hint: The $\mathrm{H}^{+}$ ion will first come off from the strongest acid group followed by the next strongest acid group and so on. (b) A dipolar ion is one in which the species has an equal number of positive and negative charges. Identify the dipolar ion in part (a). (c) The pH at which the dipolar ion predominates is called the isoelectric point, denoted by $\mathrm{p} I$. The isoelectric point is the average of the $\mathrm{p} K_{\mathrm{a}}$ values leading to and following the formation of the dipolar ion. Calculate the $\mathrm{p} I$ of histidine. (d) The histidine group plays an important role in buffering blood (the $\mathrm{pH}$ of blood is about 7.4 ). Which conjugate acid-base pair shown in part (a) is responsible for maintaining the $\mathrm{pH}$ of blood?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 127

Amino acids are building blocks of proteins. These compounds contain at least one amino group $\left(-\mathrm{NH}_{2}\right)$ and one carboxyl group ( $-\mathrm{COOH}$ ). Consider glycine $\left(\mathrm{NH}_{2} \mathrm{CH}_{2} \mathrm{COOH}\right)$. Depending on the $\mathrm{pH}$ of the solution, glycine can exist in one of three possible forms:
Fully protonated: ${ }^{+} \mathrm{NH}_{3}-\mathrm{CH}_{2}-\mathrm{COOH}$
Dipolar ion: ${ }^{+} \mathrm{NH}_{3}-\mathrm{CH}_{2}-\mathrm{COO}^{-}$
Fully ionized: $\mathrm{NH}_{2}-\mathrm{CH}_{2}-\mathrm{COO}^{-}$
Predict the predominant form of glycine at $\mathrm{pH} 1.0,7.0$, and $12.0 .$ The $\mathrm{p} K_{\mathrm{a}}$ of the carboxyl group is 2.3 and that of the ammonium group $\left(\mathrm{NH}_{3}^{+}\right)$ is 9.6 .

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 128

For the past 300 million years, the $\mathrm{pH}$ of ocean water has been fairly steady at about 8.2 . Today, it is 8.1 . Determine what percentage increase in hydronium ion concentration this $\mathrm{pH}$ change represents.

Bryce Werts

Numerade Educator

Problem 129

The maximum allowable concentration of $\mathrm{Pb}^{2+}$ ions in drinking water is $0.05 \mathrm{ppm}$ (i.e., $0.05 \mathrm{~g}$ of $\mathrm{Pb}^{2+}$ in 1 million grams of water). Is this guideline exceeded if an underground water supply is at equilibrium with the mineral anglesite $\left(\mathrm{PbSO}_{4}\right)\left(K_{\mathrm{sp}}=1.6 \times 10^{-8}\right) ?$

David Collins

Numerade Educator

Problem 130

A sample of $0.96 \mathrm{~L}$ of $\mathrm{HCl}$ gas at $372 \mathrm{mmHg}$ and $22^{\circ} \mathrm{C}$ is bubbled into $0.034 \mathrm{~L}$ of $0.57 M \mathrm{NH}_{3} .$ What is the $\mathrm{pH}$ of the resulting solution? Assume the volume of solution remains constant and that the $\mathrm{HCl}$ is totally dissolved in the solution.

David Collins

Numerade Educator

Problem 131

When lemon juice is added to tea, the color becomes lighter. In part, the color change is due to dilution, but the main reason for the change is an acid-base reaction. What is the reaction? (Hint: Tea contains "polyphenols," which are weak acids, and lemon juice contains citric acid.)

Prashant Bana

Numerade Educator

Problem 132

How many milliliters of $1.0 \mathrm{M} \mathrm{NaOH}$ must be added to $200 \mathrm{~mL}$ of $0.10 \mathrm{M} \mathrm{NaH}_{2} \mathrm{PO}_{4}$ to make a buffer solution
with a pH of $7.50 ?$

Iryna Ivaniuk

Numerade Educator

Problem 133

Which of the following solutions has the highest $\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]: (\mathrm{a}) 0.10 \mathrm{M} \mathrm{HF}$ (b) $0.10 M \mathrm{HF}$ in $0.10 \mathrm{M} \mathrm{NaF}$ (c) $0.10 \mathrm{M} \mathrm{HF}$ in $0.10 \mathrm{M} \mathrm{SbF}_{5} ?$ (Hint: $\mathrm{SbF}_{5}$ reacts with $\mathrm{F}^{-}$ to form the complex ion $\mathrm{SbF}_{6}^{-}$.)

Nicole Smina

Numerade Educator

Problem 134

Distribution curves show how the fractions of a nonionized acid and its conjugate base vary as a function of the $\mathrm{pH}$ of the medium. Plot distribution curves for $\mathrm{CH}_{3} \mathrm{COOH}$ and its conjugate base $\mathrm{CH}_{3} \mathrm{COO}^{-}$ in solution. Your graph should show fraction as the $y$ axis and $\mathrm{pH}$ as the $x$ axis. What are the fractions and $\mathrm{pH}$ at the point where the se two curves intersect?

Iryna Ivaniuk

Numerade Educator

Problem 135

A 1.0-L saturated silver carbonate solution at $5^{\circ} \mathrm{C}$ is filtered to remove undissolved solid and treated with enough hydrochloric acid to decompose the dissolved compound. The carbon dioxide generated is collected in a 19-mL vial and exerts a pressure of $114 \mathrm{mmHg}$ at $25^{\circ} \mathrm{C}$. What is the $K_{\mathrm{sp}}$ of silver carbonate at $5^{\circ} \mathrm{C} ?$

Iryna Ivaniuk

Numerade Educator

Problem 136

Draw distribution curves for an aqueous carbonic acid solution. Your graph should show fraction of species present as the $y$ axis and $\mathrm{pH}$ as the $x$ axis. Note that at any $\mathrm{pH},$ only two of the three species $\left(\mathrm{H}_{2} \mathrm{CO}_{3}, \mathrm{HCO}_{3}^{-},\right.$ and $\mathrm{CO}_{3}^{2-}$ ) are present in appreciable concentrations. Use the $K_{\mathrm{a}}$ values in Table 16.8 .

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 137

Acid-base reactions usually go to completion. Confirm this statement by calculating the equilibrium constant for each of the following cases: (a) A strong acid reacting with a strong base. (b) A strong acid reacting with a weak base $\left(\mathrm{NH}_{3}\right) .$ (c) A weak acid (CH $_{3} \mathrm{COOH}$ ) reacting with a strong base. (d) A weak acid (CH $_{3} \mathrm{COOH}$ ) reacting with a weak base $\left(\mathrm{NH}_{3}\right) .$ (Hint: Strong acids exist as $\mathrm{H}_{3} \mathrm{O}^{+}$ ions and strong bases exist as $\mathrm{OH}^{-}$ ions in solution. You need to look up $K_{a}, K_{b},$ and $K_{w \cdot}$ )

Manik Pulyani

Numerade Educator

Problem 138

Calculate $x$, the number of molecules of water in oxalic acid hydrate $\left(\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4} \cdot x \mathrm{H}_{2} \mathrm{O}\right),$ from the following data:
$5.00 \mathrm{~g}$ of the compound is made up to exactly $250 \mathrm{~mL}$ solution, and $25.0 \mathrm{~mL}$ of this solution requires $15.9 \mathrm{~mL}$ of $0.500 M \mathrm{NaOH}$ solution for neutralization.

Prashant Bana

Numerade Educator