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Chemistry

Raymond Chang, Jason Overby

Chapter 15

Acids and Bases - all with Video Answers

Educators

Chapter Questions

02:08

Problem 1

Define Bronsted acids and bases. Give an example of a conjugate pair in an acidbase reaction.

Aswathy M
Aswathy M
Numerade Educator
02:37

Problem 2

For a species to act as a Brønsted acid, an atom in the species must possess a lone pair of Explain why this is so.

James Franklin
James Franklin
Numerade Educator
02:15

Problem 3

Classify each of the following species as a Brønsted acid or base, or both: (a) $\mathrm{H}_2 \mathrm{O}$, (b) $\mathrm{OH}^{-}$,
(c) $\mathrm{H}_3 \mathrm{O}^{+}$,
(d) $\mathrm{NH}_3$,
(e) $\mathrm{NH}_4^{+}$,
(f) $\mathrm{NH}_2 2-$, (g) $\mathrm{NO}_3^{-}$,
(h) $\mathrm{CO} 32^{-}$,
(i) $\mathrm{HBr},(\mathrm{j})$ HCN .

Cheryl Glor
Cheryl Glor
Numerade Educator
03:11

Problem 4

Write the formulas of the conjugate bases of the following acids: (a) $\mathrm{HNO}_2$, (b) $\mathrm{H}_2 \mathrm{SO}_4$, (c) $\mathrm{H}_2 \mathrm{~S}$, (d) HCN , (e) HCOOH (formic acid).

James Franklin
James Franklin
Numerade Educator
01:41

Problem 5

Identify the acid-base conjugate pairs in each of the following reactions:
(a) $\mathrm{CH}_3 \mathrm{COO}^{-}+\mathrm{HCN}=\mathrm{CH}_3 \mathrm{COOH}+\mathrm{CN}^{-}$
(b) $\mathrm{HCO}_3^{-}+\mathrm{HCO}_3^{-} \rightleftharpoons \mathrm{H}_2 \mathrm{CO}_3+\mathrm{CO}_3^{2-}$
(c) $\mathrm{H}_2 \mathrm{PO}_4^{-}+\mathrm{NH}_3 \rightleftharpoons \mathrm{HPO}_4^{2-}+\mathrm{NH}_4^{+}$
(d) $\mathrm{HClO}+\mathrm{CH}_3 \mathrm{NH}_2 \rightleftharpoons \mathrm{CH}_3 \mathrm{NH}_3^{+}+\mathrm{ClO}^{-}$
(e) $\mathrm{CO}_3^{2-}+\mathrm{H}_2 \mathrm{O} \rightleftharpoons \mathrm{HCO}_3^{-}+\mathrm{OH}^{-}$

Ahmed Ali
Ahmed Ali
Numerade Educator
03:33

Problem 6

Write the formula for the conjugate acid of each of the following bases: (a) $\mathrm{HS}^{-}$, (b) $\mathrm{HCO}_3^{-}$(c) $\mathrm{CO}_3^{2-}$ -
(d) $\mathrm{H}_2 \mathrm{PO}_4^{-}$(e) $\mathrm{HPO}_4^{2-}$
(f) $\mathrm{PO} 4^{3-}$, (g) $\mathrm{HSO}_4^{-}$
(h) $\mathrm{SO}_4^{2-}$
(i) $\mathrm{SO}_3^{2-}$.

James Franklin
James Franklin
Numerade Educator
02:54

Problem 7

Oxalic acid $\left(\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4\right)$ has the following structure:
Structure can't copy
An oxalic acid solution contains the following species in varying concentrations: $\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4, \mathrm{HC}_2 \mathrm{O}_4^{-}, \mathrm{C}_2 \mathrm{O}_4^{2-}$, and $\mathrm{H}^{+}$. (a) Draw Lewis structures of $\mathrm{HC}_2 \mathrm{O}_4^{-}$and $\mathrm{C}_2 \mathrm{O}_4^{2-}$. (b) Which of the four species can act only as acids? Which can act only as bases? Which can act as both acids and bases?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:26

Problem 8

Write the formula for the conjugate base of each of the following acids: (a) $\mathrm{CH}_2 \mathrm{ClCOOH}$, (b) $\mathrm{HIO}_4$, (c) $\mathrm{H}_3 \mathrm{PO}_4$, (d) $\mathrm{H}_2 \mathrm{PO}_4^{-}$, (e) $\mathrm{HPO}_4^{2-}$, (f) $\mathrm{H}_2 \mathrm{SO}_4$ (g) $\mathrm{HSO}_4^{-}$, (h) $\mathrm{HIO}_3$, (i) $\mathrm{HSO}_3^{-}$, (j) $\mathrm{NH}_4^{+}$, (k) $\mathrm{H}_2 \mathrm{~S}$, (l) $\mathrm{HS}^{-}$, (m) HClO .

Ahmed Ali
Ahmed Ali
Numerade Educator
01:37

Problem 9

What is the ion-product constant for water?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:21

Problem 10

Write an equation relating $\left[\mathrm{H}^{+}\right]$and $\left[\mathrm{OH}^{-}\right]$in solution at $25^{\circ} \mathrm{C}$.

James Franklin
James Franklin
Numerade Educator
02:18

Problem 11

The ion-product constant for water is $1.0 \times 10^{-14}$ at $25^{\circ} \mathrm{C}$ and $3.8 \times 10^{-14}$ at $40^{\circ} \mathrm{C}$. Is the forward process
$$
\mathrm{H}_2 \mathrm{O}(l) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{OH}^{-}(a q)
$$

endothermic or exothermic?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:57

Problem 12

Define pH . Why do chemists normally choose to discuss the acidity of a solution in terms of pH rather than hydrogen ion concentration, $\left[\mathrm{H}^{+}\right]$?

James Franklin
James Franklin
Numerade Educator
01:34

Problem 13

The pH of a solution is 6.7. From this statement alone, can you conclude that the solution is acidic? If not, what additional information would you need? Can the pH of a solution be zero or negative? If so, give examples to illustrate these values.

Ahmed Ali
Ahmed Ali
Numerade Educator
02:26

Problem 14

Define pOH . Write the equation relating pH and pOH .

James Franklin
James Franklin
Numerade Educator
02:11

Problem 15

Calculate the concentration of $\mathrm{OH}^{-}$ions in a $1.4 \times 10^{-3} M \mathrm{HCl}$ solution.

Ronald Prasad
Ronald Prasad
Numerade Educator
04:03

Problem 16

Calculate the concentration of $\mathrm{H}^{+}$ions in a $0.62 M \mathrm{NaOH}$ solution.

James Franklin
James Franklin
Numerade Educator
02:22

Problem 17

Calculate the pH of each of the following solutions: (a) $0.0010 M \mathrm{HCl}$, (b) $0.76 M$ KOH .

Susan Hallstrom
Susan Hallstrom
Numerade Educator
View

Problem 18

Calculate the pH of each of the following solutions: (a) $2.8 \times 10^{-4} M \mathrm{Ba}(\mathrm{OH})_2$, (b) $5.2 \times 10^{-4} M \mathrm{HNO}_3$.

Tom Comey
Tom Comey
Numerade Educator
01:26

Problem 19

Calculate the hydrogen ion concentration in $\mathrm{mol} / \mathrm{L}$ for solutions with the following pH values: (a) 2.42 , (b) 11.21 , (c) 6.96, (d) 15.00 .

Ahmed Ali
Ahmed Ali
Numerade Educator
05:39

Problem 20

Calculate the hydrogen ion concentration in $\mathrm{mol} / \mathrm{L}$ for each of the following solutions: (a) a solution whose pH is 5.20 , (b) a solution whose pH is 16.00 , (c) a solution whose hydroxide concentration is $3.7 \times 10^{-9} M$.

James Franklin
James Franklin
Numerade Educator
01:13

Problem 21

Complete the following table for a solution:
$$
\begin{array}{c|c|c}
\hline \mathbf{p H} & {\left[\mathbf{H}^{+}\right]} & \text {Solution is } \\
\hline<7 & & \\
\hline & <1.0 \times 10^{-7} \mathrm{M} & \\
\hline & & \text { Neutral } \\
\hline
\end{array}
$$

Ahmed Ali
Ahmed Ali
Numerade Educator
01:28

Problem 22

Fill in the word acidic, basic, or neutral for the following solutions:
(a) $\mathrm{pOH}>7$ solution is
(b) $\mathrm{pOH}=7$; solution is
(c) $\mathrm{pOH}<7$; solution is

James Franklin
James Franklin
Numerade Educator
View

Problem 23

The pOH of a strong base solution is 1.88 at $25^{\circ} \mathrm{C}$. Calculate the concentration of the base if (a) the base is KOH and (b) the base is $\mathrm{Ba}(\mathrm{OH})_2$.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:28

Problem 24

Calculate the number of moles of KOH in 5.50 mL of a $0.360 M \mathrm{KOH}$ solution. What is the pOH of the solution?

James Franklin
James Franklin
Numerade Educator
02:42

Problem 25

How much NaOH (in grams) is needed to prepare 546 mL of solution with a pH of 10.00?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:51

Problem 26

A solution is made by dissolving 18.4 g of HCl in 662 mL of water. Calculate the pH of the solution. (Assume that the volume remains constant.)

James Franklin
James Franklin
Numerade Educator
04:19

Problem 27

Explain what is meant by the strength of an acid.

Sima Sarker
Sima Sarker
Numerade Educator
02:28

Problem 28

Without referring to the text, write the formulas of four strong acids and four weak acids.

James Franklin
James Franklin
Numerade Educator
01:12

Problem 29

What is the strongest acid and the strongest base that can exist in water?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:57

Problem 30

$\mathrm{H}_2 \mathrm{SO}_4$ is a strong acid, but $\mathrm{HSO}_4^{-}$is a weak acid. Account for the difference in strength of these two related species.

James Franklin
James Franklin
Numerade Educator
01:09

Problem 31

Which of the following diagrams best represents a strong acid, such as HCl , dissolved in water? Which represents a weak acid? Which represents a very weak acid? (The hydrated proton is shown as a hydronium ion. Water molecules are omitted for clarity.)
Diagram a-d can't copy

Ahmed Ali
Ahmed Ali
Numerade Educator
03:15

Problem 32

(1) Which of the following diagrams represents a solution of a weak diprotic acid?
(2) Which diagrams represent chemically implausible situations? (The hydrated proton is shown as a hydronium ion. Water molecules are omitted for clarity.)
Diagram a-d can't copy

James Franklin
James Franklin
Numerade Educator
00:51

Problem 33

Classify each of the following species as a weak or strong acid: (a) $\mathrm{HNO}_3$, (b) HF , (c) $\mathrm{H}_2 \mathrm{SO}_4$, (d) $\mathrm{HSO}_4^{-}$, (e) $\mathrm{H}_2 \mathrm{CO}_3$, (f) $\mathrm{HCO}_3^{-}$, (g) HCl, (h) HCN , (i) $\mathrm{HNO}_2$.

Ahmed Ali
Ahmed Ali
Numerade Educator
02:23

Problem 34

Classify each of the following species as a weak or strong base: (a) LiOH , (b) $\mathrm{CN}^{-}$, (c) $\mathrm{H}_2 \mathrm{O}$, (d) $\mathrm{ClO}_4^{-}$, (e) $\mathrm{NH}_2^{-}$.

James Franklin
James Franklin
Numerade Educator
01:00

Problem 35

Which of the following statements is/are true for a $0.10 M$ solution of a weak acid HA?
(a) The pH is 1.00 .
(b) $\left[\mathrm{H}^{+}\right] \gg\left[\mathrm{A}^{-}\right]$
(c) $\left[\mathrm{H}^{+}\right]=\left[\mathrm{A}^{-}\right]$
(d) The pH is less than 1 .

Nicholas Mogoi
Nicholas Mogoi
Numerade Educator
05:33

Problem 36

Which of the following statements is/are true regarding a $1.0 M$ solution of a strong acid HA?
(a) $\left[\mathrm{A}^{-}\right]>\left[\mathrm{H}^{+}\right]$
(b) The pH is 0.00 .
(c) $\left[\mathrm{H}^{+}\right]=1.0 \mathrm{M}$
(d) $[\mathrm{HA}]=1.0 \mathrm{M}$

James Franklin
James Franklin
Numerade Educator
01:13

Problem 37

Predict the direction that predominates in this reaction:

$$
\mathrm{F}^{-}(a q)+\mathrm{H}_2 \mathrm{O}(l)=\mathrm{HF}(a q)+\mathrm{OH}^{-}(a q)
$$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:15

Problem 38

Predict whether the following reaction will proceed from left to right to any measurable extent:

$$
\mathrm{CH}_3 \mathrm{COOH}(a q)+\mathrm{Cl}^{-}(a q) \rightarrow
$$

James Franklin
James Franklin
Numerade Educator
01:09

Problem 39

What does the ionization constant tell us about the strength of an acid?

Wilson Ma
Wilson Ma
The University of Alabama
02:28

Problem 40

List the factors on which the $K_{\mathrm{a}}$ of a weak acid depends.

James Franklin
James Franklin
Numerade Educator
01:58

Problem 41

Why do we normally not quote $K_{\mathrm{a}}$ values for strong acids such as HCl and $\mathrm{HNO}_3$ ? Why is it necessary to specify temperature when giving $K_{\mathrm{a}}$ values?

Ahmed Ali
Ahmed Ali
Numerade Educator
View

Problem 42

Which of the following solutions has the highest pH : (a) $0.40 M \mathrm{HCOOH}$, (b) 0.40 $M \mathrm{HClO}_4$, (c) $0.40 M \mathrm{CH}_3 \mathrm{COOH}$ ?

Tom Comey
Tom Comey
Numerade Educator
06:02

Problem 43

The $K_{\mathrm{a}}$ for benzoic acid is $6.5 \times 10^{-5}$. Calculate the pH of a 0.10 M benzoic acid solution.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
09:29

Problem 44

A $0.0560-\mathrm{g}$ quantity of acetic acid is dissolved in enough water to make 50.0 mL of solution. Calculate the concentrations of $\mathrm{H}^{+}, \mathrm{CH}_3 \mathrm{COO}^{-}$, and $\mathrm{CH}_3 \mathrm{COOH}$ at equilibrium. ( $K_{\mathrm{a}}$ for acetic acid $=1.8 \times 10^{-5}$.)

James Franklin
James Franklin
Numerade Educator
01:20

Problem 45

The pH of an acid solution is 6.20. Calculate the $K_{\mathrm{a}}$ for the acid. The initial acid concentration is $0.010 M$.

Ahmed Ali
Ahmed Ali
Numerade Educator
07:31

Problem 46

What is the original molarity of a solution of formic acid $(\mathrm{HCOOH})$ whose pH is 3.26 at equilibrium?

James Franklin
James Franklin
Numerade Educator
07:52

Problem 47

Calculate the percent ionization of benzoic acid having the following concentrations: (a) 0.20 M , (b) 0.00020 M .

Susan Hallstrom
Susan Hallstrom
Numerade Educator
19:12

Problem 48

Calculate the percent ionization of hydrofluoric acid at the following concentrations: (a) 0.60 M , (b) 0.0046 M , (c) 0.00028 M . Comment on the trends.

James Franklin
James Franklin
Numerade Educator
02:59

Problem 49

A $0.040 M$ solution of a monoprotic acid is $14 \%$ ionized. Calculate the ionization constant of the acid.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
07:17

Problem 50

(a) Calculate the percent ionization of a $0.20 M$ solution of the monoprotic acetylsalicylic acid (aspirin) for which $K_{\mathrm{a}}=3.0 \times 10^{-4}$. (b) The pH of gastric juice in the stomach of a certain individual is 1.00 . After a few aspirin tablets have been swallowed, the concentration of acetylsalicylic acid in the stomach is 0.20 M . Calculate the percent ionization of the acid under these conditions. What effect does the nonionized acid have on the membranes lining the stomach? (Hint: See the Chemistry in Action essay "Antacids and the pH Balance in Your Stomach" in Section 15.3.)

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:26

Problem 51

Use $\mathrm{NH}_3$ to illustrate what we mean by the strength of a base.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
06:10

Problem 52

Which of the following has a higher pH : (a) $0.20 M \mathrm{NH}_3$, (b) $0.20 M \mathrm{NaOH}$ ?

James Franklin
James Franklin
Numerade Educator
04:55

Problem 53

Calculate the pH of a $0.24 M$ solution of a weak base with a $K_{\mathrm{b}}$ of $3.5 \times 10^{-6}$.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:04

Problem 54

The diagrams here represent three different weak base solutions of equal concentration. List the bases in order of increasing $K_{\mathrm{b}}$ value. (Water molecules are omitted for clarity.)
Diagram a-c can't copy

James Franklin
James Franklin
Numerade Educator
06:46

Problem 55

Calculate the pH for each of the following solutions: (a) $0.10 M \mathrm{NH}_3$, (b) $0.050 M \mathrm{C}_5 \mathrm{H}_5 \mathrm{~N}$ (pyridine).

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:25

Problem 56

The pH of a 0.30 M solution of a weak base is 10.66 . What is the $K_{\mathrm{b}}$ of the base?

James Franklin
James Franklin
Numerade Educator
03:25

Problem 57

What is the original molarity of a solution of ammonia whose pH is 11.22 ?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:38

Problem 58

In a $0.080 M \mathrm{NH}_3$ solution, what percent of the $\mathrm{NH}_3$ is present as $\mathrm{NH}_4^{+}$?

James Franklin
James Franklin
Numerade Educator
04:22

Problem 59

Write the equation relating $K_{\mathrm{a}}$ for a weak acid and $K_{\mathrm{b}}$ for its conjugate base. Use $\mathrm{NH}_3$ and its conjugate acid $\mathrm{NH}_4^{+}$to derive the relationship between $K_{\mathrm{a}}$ and $K_{\mathrm{b}}$.

Anatole Borisov
Anatole Borisov
Numerade Educator
02:07

Problem 60

From the relationship $K_{\mathrm{a}} K_{\mathrm{b}}=K_{\mathrm{w}}$, what can you deduce about the relative strengths of a weak acid and its conjugate base?

James Franklin
James Franklin
Numerade Educator
01:23

Problem 61

Carbonic acid is a diprotic acid. Explain what that means.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
View

Problem 62

Write all the species (except water) that are present in a phosphoric acid solution. Indicate which species can act as a Brønsted acid, which as a Brønsted acid, and which as both a Brønsted acid and a Brønsted acid.

Tom Comey
Tom Comey
Numerade Educator
03:35

Problem 63

The first and second ionization constants of a diprotic acid $\mathrm{H}_2 \mathrm{~A}$ are $K_{\mathrm{a} 1}$ and $K_{\mathrm{a} 2}$ at a certain temperature. Under what conditions will [ $\mathrm{A}^{2-}$ ] $=K_{\mathrm{a} 2}$ ?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
08:09

Problem 64

Compare the pH of a $0.040 M \mathrm{HCl}$ solution with that of a $0.040 M \mathrm{H}_2 \mathrm{SO}_4$ solution. (Hint: $\mathrm{H}_2 \mathrm{SO}_4$ is a strong acid; $K_{\mathrm{a}}$ for $\mathrm{HSO}_4^{-}=1.3 \times 10^{-2}$.)

James Franklin
James Franklin
Numerade Educator
05:48

Problem 65

What are the concentrations of $\mathrm{HSO}_4^{-}, \mathrm{SO}_4^{2-}$, and $\mathrm{H}^{+}$in a $0.20 M \mathrm{KHSO}_4$ solution?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
08:17

Problem 66

Calculate the concentrations of $\mathrm{H}^{+}, \mathrm{HCO}_3^{-}$, and $\mathrm{CO}_3^{2-}$ in a $0.025 M \mathrm{H}_2 \mathrm{CO}_3$ solution.

James Franklin
James Franklin
Numerade Educator
01:53

Problem 67

List four factors that affect the strength of an acid.

Ronald Prasad
Ronald Prasad
Numerade Educator
05:04

Problem 68

How does the strength of an oxoacid depend on the electronegativity and oxidation number of the central atom?

James Franklin
James Franklin
Numerade Educator
02:13

Problem 69

Predict the acid strengths of the following compounds: $\mathrm{H}_2 \mathrm{O}, \mathrm{H}_2 \mathrm{~S}$, and $\mathrm{H}_2 \mathrm{Se}$.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:15

Problem 70

Compare the strengths of the following pairs of acids: (a) $\mathrm{H}_2 \mathrm{SO}_4$ and $\mathrm{H}_2 \mathrm{SeO}_4$, (b) $\mathrm{H}_3 \mathrm{PO}_4$ and $\mathrm{H}_3 \mathrm{AsO}_4$.

James Franklin
James Franklin
Numerade Educator
01:35

Problem 71

Which of the following is the stronger acid: $\mathrm{CH}_2 \mathrm{ClCOOH}$ or $\mathrm{CHCl}_2 \mathrm{COOH}$ ? Explain your choice.

Ahmed Ali
Ahmed Ali
Numerade Educator
03:48

Problem 72

Consider the following compounds:
Compounds can't copy
Experimentally, phenol is found to be a stronger acid than methanol. Explain this difference in terms of the structures of the conjugate bases. (Hint: A more stable conjugate base favors ionization. Only one of the conjugate bases can be stabilized by resonance.)

James Franklin
James Franklin
Numerade Educator
05:09

Problem 73

Define salt hydrolysis. Categorize salts according to how they affect the pH of a solution.

Sharfa Farzandh
Sharfa Farzandh
Numerade Educator
02:42

Problem 74

Explain why small, highly charged metal ions are able to undergo hydrolysis.

James Franklin
James Franklin
Numerade Educator
01:44

Problem 75

$\mathrm{Al}^{3+}$ is not a Bronsted acid but $\left.\mathrm{Al} \mathrm{H}_2 \mathrm{O}\right)_6^{3+}$ is. Explain.

Ahmed Ali
Ahmed Ali
Numerade Educator
02:17

Problem 76

Specify which of the following salts will undergo hydrolysis: $\mathrm{KF}, \mathrm{NaNO}_3, \mathrm{NH}_4 \mathrm{NO}_2$, $\mathrm{MgSO}_4, \mathrm{KCN}, \mathrm{C}_6 \mathrm{H}_5 \mathrm{COONa}, \mathrm{RbI}, \mathrm{Na}_2 \mathrm{CO}_3, \mathrm{CaCl}_2, \mathrm{HCOOK}$.

Lijeesh Krishnan
Lijeesh Krishnan
Numerade Educator
01:49

Problem 77

Predict the $\mathrm{pH}(>7,<7$, or $\approx 7$ ) of aqueous solutions containing the following salts: (a) KBr , (b) $\mathrm{Al}\left(\mathrm{NO}_3\right)_3$, (c) $\mathrm{BaCl}_2$, (d) $\mathrm{Bi}\left(\mathrm{NO}_3\right)_3$.

Ahmed Ali
Ahmed Ali
Numerade Educator
04:10

Problem 78

Predict whether the following solutions are acidic, basic, or nearly neutral: (a) NaBr , (b) $\mathrm{K}_2 \mathrm{SO}_3$,
(c) $\mathrm{NH}_4 \mathrm{NO}_2$,
(d) $\mathrm{Cr}\left(\mathrm{NO}_3\right)_3$.

James Franklin
James Franklin
Numerade Educator
02:10

Problem 79

A certain salt, MX (containing the $\mathrm{M}^{+}$and $\mathrm{X}^{-}$ions), is dissolved in water, and the pH of the resulting solution is 7.0 . Can you say anything about the strengths of the acid and the base from which the salt is derived?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:39

Problem 80

In a certain experiment a student finds that the pHs of $0.10 M$ solutions of three potassium salts KX, KY, and KZ are $7.0,9.0$, and 11.0 , respectively. Arrange the acids $\mathrm{HX}, \mathrm{HY}$, and HZ in the order of increasing acid strength.

Ahmed Ali
Ahmed Ali
Numerade Educator
04:17

Problem 81

Calculate the pH of a $0.36 M \mathrm{CH}_3 \mathrm{COONa}$ solution.

Adriano Chikande
Adriano Chikande
Numerade Educator
04:34

Problem 82

Calculate the pH of a $0.42 M \mathrm{NH}_4 \mathrm{Cl}$ solution.

James Franklin
James Franklin
Numerade Educator
00:38

Problem 83

Predict the $\mathrm{pH}(>7,<7, \approx 7)$ of a $\mathrm{NaHCO}_3$ solution.

Ahmed Ali
Ahmed Ali
Numerade Educator
02:25

Problem 84

Predict whether a solution containing the salt $\mathrm{K}_2 \mathrm{HPO}_4$ will be acidic, neutral, or basic.

James Franklin
James Franklin
Numerade Educator
01:22

Problem 85

Classify the following oxides as acidic, basic, amphoteric, or neutral: (a) $\mathrm{CO}_2$, (b) $\mathrm{K}_2 \mathrm{O}$, (c) CaO , (d) $\mathrm{N}_2 \mathrm{O}_5$, (e) CO , (f) NO , (g) $\mathrm{SnO}_2$, (h) $\mathrm{SO}_3$, (i) $\mathrm{Al}_2 \mathrm{O}_3$, (j) BaO .

Ahmed Ali
Ahmed Ali
Numerade Educator
01:51

Problem 86

Write equations for the reactions between (a) $\mathrm{CO}_2$ and $\mathrm{NaOH}(a q)$, (b) $\mathrm{Na}_2 \mathrm{O}$ and $\mathrm{HNO}_3(a q)$.

James Franklin
James Franklin
Numerade Educator
01:25

Problem 87

Explain why metal oxides tend to be basic if the oxidation number of the metal is low and acidic if the oxidation number of the metal is high. (Hint: Metallic compounds in which the oxidation numbers of the metals are low are more ionic than those in which the oxidation numbers of the metals are high.)

Ahmed Ali
Ahmed Ali
Numerade Educator
01:50

Problem 88

Arrange the oxides in each of the following groups in order of increasing basicity: (a) $\mathrm{K}_2 \mathrm{O}, \mathrm{Al}_2 \mathrm{O}_3, \mathrm{BaO}$, (b) $\mathrm{CrO}_3, \mathrm{CrO}, \mathrm{Cr}_2 \mathrm{O}_3$.

James Franklin
James Franklin
Numerade Educator
01:09

Problem 89

$\mathrm{Zn}(\mathrm{OH})_2$ is an amphoteric hydroxide. Write balanced ionic equations to show its reaction with (a) HCl , (b) NaOH [the product is $\mathrm{Zn}(\mathrm{OH})_4^{2-}$ ].

Ahmed Ali
Ahmed Ali
Numerade Educator
01:19

Problem 90

$\mathrm{Al}(\mathrm{OH})_3$ is an insoluble compound. It dissolves in excess NaOH in solution. Write a balanced ionic equation for this reaction. What type of reaction is this?

James Franklin
James Franklin
Numerade Educator
02:28

Problem 91

What are the Lewis definitions of an acid and a base? In what way are they more general than the Bronsted definitions?

Lijeesh Krishnan
Lijeesh Krishnan
Numerade Educator
03:39

Problem 92

In terms of orbitals and electron arrangements, what must be present for a molecule or an ion to act as a Lewis acid (use $\mathrm{H}^{+}$and $\mathrm{BF}_3$ as examples)? What must be present for a molecule or ion to act as a Lewis base (use $\mathrm{OH}^{-}$and $\mathrm{NH}_3$ as examples)?

James Franklin
James Franklin
Numerade Educator
00:58

Problem 93

Classify each of the following species as a Lewis acid or a Lewis base: (a) $\mathrm{CO}_2$, (b) $\mathrm{H}_2 \mathrm{O}$, (c) $\mathrm{I}^{-}$, (d) $\mathrm{SO}_2$, (e) $\mathrm{NH}_3$, (f) $\mathrm{OH}^{-}$, (g) $\mathrm{H}^{+}$, (h) $\mathrm{BCl}_3$.

Ahmed Ali
Ahmed Ali
Numerade Educator
00:59

Problem 94

Describe the following reaction in terms of the Lewis theory of acids and bases:

$$
\mathrm{AlCl}_3(s)+\mathrm{Cl}^{-}(a q) \rightarrow \mathrm{AlCl} 4-(a q)
$$

Ahmed Ali
Ahmed Ali
Numerade Educator
01:16

Problem 95

Which would be considered a stronger Lewis acid: (a) $\mathrm{BF}_3$ or $\mathrm{BCl}_3$, (b) $\mathrm{Fe}^{2+}$ or $\mathrm{Fe}^{3+}$ ? Explain.

Ahmed Ali
Ahmed Ali
Numerade Educator
01:29

Problem 96

All Brønsted acids are Lewis acids, but the reverse is not true. Give two examples of Lewis acids that are not Bronsted acids.

James Franklin
James Franklin
Numerade Educator
06:10

Problem 97

Determine the concentration of a $\mathrm{NaNO}_2$ solution that has a pH of 8.22 .

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:57

Problem 98

Determine the concentration of a $\mathrm{NH}_4 \mathrm{Cl}$ solution that has a pH of 5.64 .

James Franklin
James Franklin
Numerade Educator
03:07

Problem 99

The diagrams here show three weak acids HA ( $\mathrm{A}=\mathrm{X}, \mathrm{Y}$, or Z ) in solution. (a) Arrange the acids in order of increasing $K_{\mathrm{a}}$. (b) Arrange the conjugate bases in increasing order of $K_{\mathrm{b}}$. (c) Calculate the percent ionization of each acid. (d) Which of the $0.1 M$ sodium salt solutions ( $\mathrm{NaX}, \mathrm{NaY}$, or NaZ ) has the lowest pH ? (The hydrated proton is shown as a hydronium ion. Water molecules are omitted for clarity.)
Diagrams can't copy

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:51

Problem 100

A typical reaction between an antacid and the hydrochloric acid in gastric juice is

$$
\begin{gathered}
\mathrm{NaHCO}_3(s)+\mathrm{HCl}(a q)= \\
\mathrm{NaCl}(a q)+\mathrm{H}_2 \mathrm{O}(l)+\mathrm{CO}_2(g)
\end{gathered}
$$

Calculate the volume (in L ) of $\mathrm{CO}_2$ generated from 0.350 g of $\mathrm{NaHCO}_3$ and excess gastric juice at 1.00 atm and $37.0^{\circ} \mathrm{C}$.

James Franklin
James Franklin
Numerade Educator
02:45

Problem 101

To which of the following would the addition of an equal volume of 0.60 M NaOH lead to a solution having a lower pH : (a) water, (b) $0.30 M \mathrm{HCl}$, (c) $0.70 M \mathrm{KOH}$, (d) $0.40 M \mathrm{NaNO}_3$ ?

Ahmed Ali
Ahmed Ali
Numerade Educator
01:17

Problem 102

The pH of a $0.0642 M$ solution of a monoprotic acid is 3.86 . Is this a strong acid?

James Franklin
James Franklin
Numerade Educator
02:19

Problem 103

Like water, liquid ammonia undergoes autoionization:

$$
\mathrm{NH}_3+\mathrm{NH}_3=\mathrm{NH}_4^{+}+\mathrm{NH} 2-
$$

(a) Identify the Brønsted acids and Brønsted acids in this reaction.
(b) What species correspond to $\mathrm{H}^{+}$and $\mathrm{OH}^{-}$and what is the condition for a neutral solution?

Nicole Krahulik
Nicole Krahulik
Numerade Educator
02:06

Problem 104

HA and HB are both weak acids although HB is the stronger of the two. Will it take a larger volume of a $0.10 M \mathrm{NaOH}$ solution to neutralize 50.0 mL of $0.10 M \mathrm{HB}$ than would be needed to neutralize 50.0 mL of $0.10 M \mathrm{HA}$ ?

James Franklin
James Franklin
Numerade Educator
01:25

Problem 105

A solution contains a weak monoprotic acid HA and its sodium salt NaA both at 0.1 $M$ concentration. Show that $\left[\mathrm{OH}^{-}\right]=K_{\mathrm{w}} / K_{\mathrm{a}}$.

Ahmed Ali
Ahmed Ali
Numerade Educator
00:34

Problem 106

The three common chromium oxides are $\mathrm{CrO}, \mathrm{Cr}_2 \mathrm{O}_3$, and $\mathrm{CrO}_3$. If $\mathrm{Cr}_2 \mathrm{O}_3$ is amphoteric, what can you say about the acid-base properties of CrO and $\mathrm{CrO}_3$ ?

Ahmed Ali
Ahmed Ali
Numerade Educator
04:03

Problem 107

Use the data in Table 15.3 to calculate the equilibrium constant for the following reaction:

$$
\mathrm{HCOOH}(a q)+\mathrm{OH}^{-}(a q)=\mathrm{HCOO}^{-}(a q)+\mathrm{H}_2 \mathrm{O}(l)
$$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:32

Problem 108

Use the data in Table 15.3 to calculate the equilibrium constant for the following reaction:

$$
\begin{aligned}
& \mathrm{CH}_3 \mathrm{COOH}(a q)+\mathrm{NO}_2^{-}(a q) \rightleftharpoons \\
& \mathrm{CH}_3 \mathrm{COO}^{-}(a q)+\mathrm{HNO}_2(a q)
\end{aligned}
$$

James Franklin
James Franklin
Numerade Educator
02:04

Problem 109

Most of the hydrides of Group 1 and Group 2 metals are ionic (the exceptions are $\mathrm{BeH}_2$ and $\mathrm{MgH}_2$, which are covalent compounds). (a) Describe the reaction between the hydride ion ( $\mathrm{H}^{-}$) and water in terms of a Brønsted acid-base reaction. (b) The same reaction can also be classified as a redox reaction. Identify the oxidizing and reducing agents.

Nicole Smina
Nicole Smina
Numerade Educator
02:19

Problem 110

Calculate the pH of a $0.20 M$ ammonium acetate $\left(\mathrm{CH}_3 \mathrm{COONH}_4\right)$ solution.

James Franklin
James Franklin
Numerade Educator
05:34

Problem 111

Novocaine, used as a local anesthetic by dentists, is a weak base ( $K_{\mathrm{b}}=8.91 \times 10^{-6}$ ). What is the ratio of the concentration of the base to that of its acid in the blood plasma ( $\mathrm{pH}=7.40$ ) of a patient?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:09

Problem 112

Which of the following is the stronger base: $\mathrm{NF}_3$ or $\mathrm{NH}_3$ ? (Hint: F is more electronegative than H .)

Ahmed Ali
Ahmed Ali
Numerade Educator
01:05

Problem 113

Which of the following is a stronger base: $\mathrm{NH}_3$ or $\mathrm{PH}_3$ ? (Hint: The $\mathrm{N}-\mathrm{H}$ bond is stronger than the $\mathrm{P}-\mathrm{H}$ bond.)

Ahmed Ali
Ahmed Ali
Numerade Educator
03:04

Problem 114

The ion product of $\mathrm{D}_2 \mathrm{O}$ is $1.35 \times 10^{-15}$ at $25^{\circ} \mathrm{C}$. (a) Calculate pD where $\mathrm{pD}=-\log \left[\mathrm{D}^{+}\right]$. (b) For what values of pD will a solution be acidic in $\mathrm{D}_2 \mathrm{O}$ ? (c) Derive a relation between pD and pOD .

James Franklin
James Franklin
Numerade Educator
01:26

Problem 115

Give an example of the following: (a) a weak acid that contains oxygen atoms, (b) a weak acid that does not contain oxygen atoms, (c) a neutral molecule that acts as a Lewis acid, (d) a neutral molecule that acts as a Lewis base, (e) a weak acid that contains two ionizable H atoms, (f) a conjugate acid-base pair, both of which react with HCl to give carbon dioxide gas.

Ahmed Ali
Ahmed Ali
Numerade Educator
01:53

Problem 116

What is the pH of 250.0 mL of an aqueous solution containing 0.616 g of the strong acid trifluoromethane sulfonic acid $\left(\mathrm{CF}_3 \mathrm{SO}_3 \mathrm{H}\right)$ ?

James Franklin
James Franklin
Numerade Educator
02:37

Problem 117

(a) Use VSEPR to predict the geometry of the hydronium ion, $\mathrm{H}_3 \mathrm{O}^{+}$. (b) The O atom in $\mathrm{H}_2 \mathrm{O}$ has two lone pairs and in principle can accept two $\mathrm{H}^{+}$ions. Explain why the species $\mathrm{H}_4 \mathrm{O}^{2+}$ does not exist. What would be its geometry if it did exist?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:17

Problem 118

HF is a weak acid, but its strength increases with concentration. Explain. (Hint: $\mathrm{F}^{-}$ reacts with HF to form $\mathrm{HF} 2-$. The equilibrium constant for this reaction is 5.2 at $25^{\circ} \mathrm{C}$.)

James Franklin
James Franklin
Numerade Educator
03:34

Problem 119

When chlorine reacts with water, the resulting solution is weakly acidic and reacts with $\mathrm{AgNO}_3$ to give a white precipitate. Write balanced equations to represent these reactions. Explain why manufacturers of household bleaches add bases such as NaOH to their products to increase their effectiveness.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:37

Problem 120

When the concentration of a strong acid is not substantially higher than $1.0 \times 10^{-7} M$, the ionization of water must be taken into account in the calculation of the solution's pH . (a) Derive an expression for the pH of a strong acid solution, including the contribution to $\left[\mathrm{H}^{+}\right]$from $\mathrm{H}_2 \mathrm{O}$. (b) Calculate the pH of a $1.0 \times 10^{-7} M$ HCl solution.

Adriano Chikande
Adriano Chikande
Numerade Educator
04:06

Problem 121

Calculate the pH of a $2.00 M \mathrm{NH}_4 \mathrm{CN}$ solution.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:49

Problem 122

Calculate the concentrations of all species in a $0.100 M \mathrm{H}_3 \mathrm{PO}_4$ solution.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
04:13

Problem 123

Identify the Lewis acid and Lewis base that lead to the formation of the following species: (a) $\mathrm{AlCl}_4^{-}$, (b) $\mathrm{Cd}(\mathrm{CN})_4^{2-}$, (c) $\mathrm{HCO}_3^{-}$, (d) $\mathrm{H}_2 \mathrm{SO}_4$.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:50

Problem 124

Very concentrated NaOH solutions should not be stored in Pyrex glassware. Why? (Hint: See Section 11.7.)

Nicholas Mogoi
Nicholas Mogoi
Numerade Educator
08:25

Problem 125

In the vapor phase, acetic acid molecules associate to a certain extent to form dimers:

$$
2 \mathrm{CH}_3 \mathrm{COOH}(\mathrm{~g}) \rightleftharpoons\left(\mathrm{CH}_3 \mathrm{COOH}\right)_2(\mathrm{~g})
$$

At $51^{\circ} \mathrm{C}$ the pressure of a certain acetic acid vapor system is 0.0342 atm in a $360-\mathrm{mL}$ flask. The vapor is condensed and neutralized with 13.8 mL of $0.0568 M \mathrm{NaOH}$. (a) Calculate the degree of dissociation $(\alpha)$ of the dimer under these conditions:

$$
\left(\mathrm{CH}_3 \mathrm{COOH}\right)_2=2 \mathrm{CH}_3 \mathrm{COOH}
$$

(Hint: See Problem 14.117 for general procedure.) (b) Calculate the equilibrium constant $K_{\mathrm{P}}$ for the reaction in (a).

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:39

Problem 126

Calculate the concentrations of all the species in a $0.100 M \mathrm{Na}_2 \mathrm{CO}_3$ solution.

Nicole Krahulik
Nicole Krahulik
Numerade Educator
View

Problem 127

Henry's law constant for $\mathrm{CO}_2$ at $38^{\circ} \mathrm{C}$ is $2.28 \times 10^{-3} \mathrm{~mol} / \mathrm{L} \cdot \mathrm{atm}$. Calculate the pH of a solution of $\mathrm{CO}_2$ at $38^{\circ} \mathrm{C}$ in equilibrium with the gas at a partial pressure of 3.20 atm .

Dominador Tan
Dominador Tan
Numerade Educator
00:41

Problem 128

Hydrocyanic acid (HCN) is a weak acid and a deadly poisonous compound-in the gaseous form (hydrogen cyanide) it is used in gas chambers. Why is it dangerous to treat sodium cyanide with acids (such as HCl ) without proper ventilation?

Ahmed Ali
Ahmed Ali
Numerade Educator
02:00

Problem 129

How many grams of NaCN would you need to dissolve in enough water to make exactly 250 mL of solution with a pH of 10.00 ?

Lottie Adams
Lottie Adams
Numerade Educator
04:30

Problem 130

A solution of formic acid $(\mathrm{HCOOH})$ has a pH of 2.53 . How many grams of formic acid are there in 100.0 mL of the solution?

Anatole Borisov
Anatole Borisov
Numerade Educator
05:33

Problem 131

Calculate the pH of a 1-L solution containing 0.150 mole of $\mathrm{CH}_3 \mathrm{COOH}$ and 0.100 mole of HCl .

Susan Hallstrom
Susan Hallstrom
Numerade Educator
05:05

Problem 132

A 1.87-g sample of Mg reacts with 80.0 mL of a HCl solution whose pH is -0.544 . What is the pH of the solution after all the Mg has reacted? Assume constant volume.

Nicholas Mogoi
Nicholas Mogoi
Numerade Educator
03:25

Problem 133

You are given two beakers, one containing an aqueous solution of strong acid (HA) and the other an aqueous solution of weak acid (HB) of the same concentration. Describe how you would compare the strengths of these two acids by (a) measuring the pH , (b) measuring electrical conductance, (c) studying the rate of hydrogen gas evolution when these solutions are reacted with an active metal such as Mg or Zn .

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:02

Problem 134

Use Le ChĂ¢telier's principle to predict the effect of the following changes on the extent of hydrolysis of sodium nitrite $\left(\mathrm{NaNO}_2\right)$ solution: (a) HCl is added, (b) NaOH is added, (c) NaCl is added, (d) the solution is diluted.

Adriano Chikande
Adriano Chikande
Numerade Educator
01:15

Problem 135

Describe the hydration of $\mathrm{SO}_2$ as a Lewis acid-base reaction. (Hint: Refer to the discussion of the hydration of $\mathrm{CO}_2$ in Section 15.12.)

Nicole Smina
Nicole Smina
Numerade Educator
00:32

Problem 136

The disagreeable odor of fish is mainly due to organic compounds $\left(\mathrm{RNH}_2\right)$ containing an amino group, $-\mathrm{NH}_2$, where R is the rest of the molecule. Amines are bases just like ammonia. Explain why putting some lemon juice on fish can greatly reduce the odor.

Ahmed Ali
Ahmed Ali
Numerade Educator
06:09

Problem 137

A solution of methylamine $\left(\mathrm{CH}_3 \mathrm{NH}_2\right)$ has a pH of 10.64 . How many grams of methylamine are there in 100.0 mL of the solution?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:01

Problem 138

$\mathrm{~A} 0.400 M$ formic acid $(\mathrm{HCOOH})$ solution freezes at $-0.758^{\circ} \mathrm{C}$. Calculate the $K_{\mathrm{a}}$ of the acid at that temperature. (Hint: Assume that molarity is equal to molality. Carry your calculations to three significant figures and round off to two for $K_{\mathrm{a}}$.)

David Collins
David Collins
Numerade Educator
01:54

Problem 139

Both the amide ion $\left(\mathrm{NH}_2^{-}\right)$and the nitride ion $\left(\mathrm{N}^{3-}\right)$ are stronger bases than the hydroxide ion and hence do not exist in aqueous solutions. (a) Write equations showing the reactions of these ions with water, and identify the Brønsted acid and base in each case. (b) Which of the two is the stronger base?

Adriano Chikande
Adriano Chikande
Numerade Educator
04:41

Problem 140

The atmospheric sulfur dioxide $\left(\mathrm{SO}_2\right)$ concentration over a certain region is 0.12 ppm by volume. Calculate the pH of the rainwater due to this pollutant. Assume that the dissolution of $\mathrm{SO}_2$ does not affect its pressure.

Adriano Chikande
Adriano Chikande
Numerade Educator
06:02

Problem 141

Calcium hypochlorite $\left[\mathrm{Ca}(\mathrm{OCl})_2\right]$ is used as a disinfectant for swimming pools. When dissolved in water it produces hypochlorous acid:

$$
\begin{aligned}
& \mathrm{Ca}(\mathrm{OCl})_2(s)+2 \mathrm{H}_2 \mathrm{O}(l)= \\
& 2 \mathrm{HClO}(a q)+\mathrm{Ca}(\mathrm{OH})_2(s)
\end{aligned}
$$

which ionizes as follows:

$$
\mathrm{HClO}(a q) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{ClO}^{-}(a q) K_{\mathrm{a}}=3.0 \times 10^{-8}
$$

As strong oxidizing agents, both HClO and $\mathrm{ClO}^{-}$can kill bacteria by destroying their cellular components. However, too high a HClO concentration is irritating to the eyes of swimmers and too high a concentration of $\mathrm{ClO}^{-}$will cause the ions to decompose in sunlight. The recommended pH for pool water is 7.8 . Calculate the percent of these species present at this pH .

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:17

Problem 142

Explain the action of smelling salt, which is ammonium carbonate $\left[\left(\mathrm{NH}_4\right)_2 \mathrm{CO}_3\right]$. (Hint: The thin film of aqueous solution that lines the nasal passage is slightly basic.)

Adriano Chikande
Adriano Chikande
Numerade Educator
10:03

Problem 143

About half of the hydrochloric acid produced annually in the United States ( 3.0 billion pounds) is used in metal pickling. This process involves the removal of metal oxide layers from metal surfaces to prepare them for coating. (a) Write the overall and net ionic equations for the reaction between iron(III) oxide, which represents the rust layer over iron, and HCl . Identify the Brønsted acid and base. (b) Hydrochloric acid is also used to remove scale (which is mostly $\mathrm{CaCO}_3$ ) from water pipes (see Chemistry in Action essay "An Undesirable Precipitation Reaction" in Section 4.2). Hydrochloric acid reacts with calcium carbonate in two stages; the first stage forms the bicarbonate ion, which then reacts further to form carbon dioxide. Write equations for these two stages and for the overall reaction. (c) Hydrochloric acid is used to recover oil from the ground. It dissolves rocks (often $\mathrm{CaCO}_3$ ) so that the oil can flow more easily. In one process, a $15 \%$ (by mass) HCl solution is injected into an oil well to dissolve the rocks. If the density of the acid solution is $1.073 \mathrm{~g} / \mathrm{mL}$, what is the pH of the solution?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:40

Problem 144

Which of the following does not represent a Lewis acid-base reaction?
(a) $\mathrm{H}_2 \mathrm{O}+\mathrm{H}^{+} \rightarrow \mathrm{H}_3 \mathrm{O}^{+}$
(b) $\mathrm{NH}_3+\mathrm{BF}_3 \rightarrow \mathrm{H}_3 \mathrm{NBF}_3$
(c) $\mathrm{PF}_3+\mathrm{F}_2 \rightarrow \mathrm{PF}_5$
(d) $\mathrm{Al}(\mathrm{OH})_3+\mathrm{OH}^{-} \longrightarrow \mathrm{Al}(\mathrm{OH})_4^{-}$

Anatole Borisov
Anatole Borisov
Numerade Educator
04:01

Problem 145

True or false? If false, explain why each statement is wrong. (a) All Lewis acids are Bronsted acids. (b) The conjugate base of an acid always carries a negative charge. (c) The percent ionization of a base increases with its concentration in solution. (d) A solution of barium fluoride is acidic.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
07:41

Problem 146

How many milliliters of a strong monoprotic acid solution at $\mathrm{pH}=4.12$ must be added to 528 mL of the same acid solution at $\mathrm{pH}=5.76$ to change its pH to 5.34 ? Assume that the volumes are additive.

Vishal Sharma
Vishal Sharma
Numerade Educator
04:38

Problem 147

Calculate the pH and percent ionization of a $0.80 M \mathrm{HNO}_2$ solution.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:30

Problem 148

Consider the two weak acids HX (molar mass $=180 \mathrm{~g} / \mathrm{mol}$ ) and HY (molar mass = $78.0 \mathrm{~g} / \mathrm{mol}$ ). If a solution of $16.9 \mathrm{~g} / \mathrm{L}$ of HX has the same pH as one containing 9.05 $\mathrm{g} / \mathrm{L}$ of HY , which is the stronger acid at these concentrations?

Adriano Chikande
Adriano Chikande
Numerade Educator
05:06

Problem 149

Hemoglobin $(\mathrm{Hb})$ is a blood protein that is responsible for transporting oxygen. It can exist in the protonated form as $\mathrm{HbH}^{+}$. The binding of oxygen can be represented by the simplified equation

$$
\mathrm{HbH}^{+}+\mathrm{O}_2=\mathrm{HbO}_2+\mathrm{H}^{+}
$$

(a) What form of hemoglobin is favored in the lungs where oxygen concentration is highest? (b) In body tissues, where the cells release carbon dioxide produced by metabolism, the blood is more acidic due to the formation of carbonic acid. What form of hemoglobin is favored under this condition? (c) When a person hyperventilates, the concentration of $\mathrm{CO}_2$ in his or her blood decreases. How does this action affect the abovementioned equilibrium? Frequently a person who is hyperventilating is advised to breathe into a paper bag. Why does this action help the individual?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
View

Problem 150

A 1.294-g sample of a metal carbonate ( $\mathrm{MCO}_3$ ) is reacted with 500 mL of a 0.100 M HCl solution. The excess HCl acid is then neutralized by 32.80 mL of $0.588 M$ NaOH . Identify M .

Tom Comey
Tom Comey
Numerade Educator
07:22

Problem 151

Prove the statement that when the concentration of a weak acid HA decreases by a factor of 10 , its percent ionization increases by a factor of $\sqrt{10}$. State any assumptions.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:28

Problem 152

Calculate the pH of a solution that is $1.00 M \mathrm{HCN}$ and $1.00 M \mathrm{HF}$. Compare the concentration (in molarity) of the $\mathrm{CN}^{-}$ion in this solution with that in a $1.00 M \mathrm{HCN}$ solution. Comment on the difference.

David Collins
David Collins
Numerade Educator
04:18

Problem 153

Teeth enamel is hydroxyapatite $\left[\mathrm{Ca}_3\left(\mathrm{PO}_4\right)_3 \mathrm{OH}\right]$. When it dissolves in water (a process called demineralization), it dissociates as follows:

$$
\mathrm{Ca}_5\left(\mathrm{PO}_4\right)_3 \mathrm{OH} \rightarrow 5 \mathrm{Ca}^{2+}+3 \mathrm{PO} 43-+\mathrm{OH}^{-}
$$

The reverse process, called remineralization, is the body's natural defense against tooth decay. Acids produced from food remove the $\mathrm{OH}^{-}$ions and thereby weaken the enamel layer. Most toothpastes contain a fluoride compound such as NaF or $\mathrm{SnF}_2$. What is the function of these compounds in preventing tooth decay?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:57

Problem 154

Use the van't Hoff equation (see Problem 14.119) and the data in Appendix 2 to calculate the pH of water at its normal boiling point.

David Collins
David Collins
Numerade Educator
07:37

Problem 155

At $28^{\circ} \mathrm{C}$ and 0.982 atm , gaseous compound HA has a density of $1.16 \mathrm{~g} / \mathrm{L}$. A quantity of 2.03 g of this compound is dissolved in water and diluted to exactly 1 L . If the pH of the solution is 5.22 (due to the ionization of HA ) at $25^{\circ} \mathrm{C}$, calculate the $K_{\mathrm{a}}$ of the acid.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
10:07

Problem 156

A 10.0-g sample of white phosphorus was burned in an excess of oxygen. The product was dissolved in enough water to make 500 mL of solution. Calculate the pH of the solution at $25^{\circ} \mathrm{C}$.

Arpit Gupta
Arpit Gupta
Numerade Educator
03:24

Problem 157

Calculate the pH of a $0.20 M \mathrm{NaHCO}_3$ solution. (Hint: As an approximation, calculate hydrolysis and ionization separately first, followed by partial neutralization.)

David Collins
David Collins
Numerade Educator
03:47

Problem 158

(a) Shown here is a solution containing hydroxide ions and hydronium ions. What is the pH of the solution? (b) How many $\mathrm{H}_3 \mathrm{O}^{+}$ions would you need to draw for every $\mathrm{OH}^{-}$ion if the pH of the solution is 5.0 ? The color codes are $\mathrm{H}_3 \mathrm{O}^{+}$(red) and $\mathrm{OH}^{-}$ (green). Water molecules and counter ions are omitted for clarity.
Diagram can't copy

David Collins
David Collins
Numerade Educator
01:43

Problem 159

In this chapter, $\mathrm{HCl}, \mathrm{HBr}$, and HI are all listed as strong acids because they are assumed to be ionized completely in water. If, however, we choose a solvent such as acetic acid that is a weaker Brønsted acid than water, it is possible to rank the acids in increasing strength as $\mathrm{HCl}<\mathrm{HBr}<\mathrm{HI}$. (a) Write equations showing proton transfer between the acids and $\mathrm{CH}_3 \mathrm{COOH}$. Describe how you would compare the strength of the acids in this solvent experimentally. (b) Draw a Lewis structure of the conjugate acid $\mathrm{CH}_3 \mathrm{COOH}_2^{+}$.

David Collins
David Collins
Numerade Educator
01:31

Problem 160

Use the data in Appendix 2 to calculate the $\Delta H_{\mathrm{nin}}$ for the following reactions: (a) $\mathrm{NaOH}(a q)+\mathrm{HCl}(a q) \rightarrow \mathrm{NaCl}(a q)+\mathrm{H}_2 \mathrm{O}(l)$; (b) $\mathrm{KOH}(a q)+\mathrm{HNO}_3(a q) \rightarrow \mathrm{KNO}_3(a q)+\mathrm{H}_2 \mathrm{O}(l)$. Comment on your results.

David Collins
David Collins
Numerade Educator