Chemistry An Atoms First Approach

Steven S. Zumdahl, Susan A. Zumdahl

Chapter 13

Acids and Bases - all with Video Answers

Educators

Chapter Questions

Problem 1

Consider two beakers of pure wader at different temperatures. How do their pH values compare? Which is move acidic? More basic? Explain.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 1

What is meant by pH ? True or false: A strong acid solution always has a lower pH than a weak acid solution. Explain.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 2

Differentiate between the serms sarengrh and concentration as they apply to acids and bases. When is HCl strong? Weak? Concentrated? Dilute? Answer the same questions for ammonia. Is the conjugate has of a weak acid a strong base?

Eric Ferrara

Numerade Educator

Problem 3

Sketch two graphs: (a) percent dissociation for weak acid HA versus the initial concentration of $\mathrm{HA}_{\text {(fHA }}^{\mathrm{a}}$ ) and (b) $\mathrm{H}^{+}$concentration versius $(\mathrm{HA}$ ) Explain both.

Ronald Prasad

Numerade Educator

Problem 3

Explain why the following are done, both of which are related to acid-base chemistry.
a. Power plants burning coal with high sulfur content use scrubbers to help eliminate sulfur emissions.
b. A gardener mixes lime $(\mathrm{CaO})$ into the soil of his garden.

Eric Ferrara

Numerade Educator

Problem 4

Consider a solution prepared by mixing a weak acid HA and HCl. What are the major species? Explain what is occurring in soluation. Hore woald yoa calculate the pH? What if you added NaA to this solution? Then added NaOH ?

Eric Ferrara

Numerade Educator

Problem 4

Values of $K_{\mathrm{w}}$ as a function of temperature are as follows:

$$
\begin{array}{|cc|}
\hline \text { Temperature }{ }^{\circ} \mathrm{C} \text { ) } & \mathrm{K}_{\mathrm{w}} \\
\hline 0 & 1.14 \times 10^{-15} \\
25 & 1.00 \times 10^{-14} \\
35 & 2.09 \times 10^{-14} \\
40 . & 2.92 \times 10^{-14} \\
50 . & 5.47 \times 10^{-14} \\
\hline
\end{array}
$$

a. Is the autoionization of water exothermic or endothermic?
b. Calculate $\left[\mathrm{H}^{+}\right]$and $\left[\mathrm{OH}^{-}\right]$in a neutral solution at $50{ }^{\circ} \mathrm{C}$.

Sima Sarker

Numerade Educator

Problem 5

Explain why salts can be acidic, basic, oe neutral, and show evanples. Do this without specific numbers.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 6

Consider two separate aqueous solutions: one of a weak acid HA and one of HCL. Assuming you started with 10 molecules of each:
a. Draw a picture of what each solution lools like at equilibrium.
b. What are the major species in each beaker?
c. From your pictures, calculate the $K_4$ values of each acid.
d. Order the following from the sir congest to the weakest base: $\mathrm{H}_2 \mathrm{O}_4 \mathrm{~A}^{-}, \mathrm{Cl}^{-}$. Explain your conder.

Eric Ferrara

Numerade Educator

Problem 7

You are asked to calculate the $\mathrm{H}^{+}$concemaration in a solution of $\mathrm{NaOH}(\mathrm{aq})$. Because sodium hydroxide is a base, can we say there is mo $\mathrm{H}^{+}$, since having $\mathrm{H}^{+}$would imply that the solutice is acidic?

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 7

A solution of formic acid $\left(\mathrm{HCOOH}, K_{\mathrm{a}}=1.8 \times 10^{-4}\right)$ has a pH of 2.70 . Calculate the initial concentration of formic acid in this solution.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 8

Consider a solation prepared by mixing a weak acid HA, HCl, and N_A. Which of the following statements best describes what happens?
a. The $\mathrm{H}^{+}$from the HCl reacss completely with the $\mathrm{A}^{-}$from the NaA. Then the HA dissociates sonewhat.
b. The $\mathrm{H}^{+}$from the HCl reaces somewhat with the $\mathrm{A}^{-}$from the NaA to mabe HA, while the HA is diswociating.
Eventually yoa have equal ansouncs of everything.
c. The $\mathrm{H}^{+}$from the HCl reacss somewhat with the $\mathrm{A}^{-}$from the NaA to make HA while the HA is dissociating. Eventually all the reactions have equal rates.
d. The $\mathrm{H}^{+}$from the HCl reacsi completely with the $\mathrm{A}^{-}$from the NaA. Then the HA dissociates sonsewhat unal 'voo much $\mathrm{H}^{+}$and $\mathrm{A}^{-}$are formed, so the $\mathrm{H}^{+}$and $\mathrm{A}^{-}$react so form HA , and so on. Eventually equilibrium is reached.
Justify your choice, and for choices you did not pick, explain what is wrong with them.

Ronald Prasad

Numerade Educator

Problem 9

Concider a solution formed by mixing 100.0 mL of 0.10 M $\mathrm{HA}\left(K_4=1.0 \times 10^{-6}\right), 100.00 \mathrm{~mL}$ of 0.10 M NaA , and 100.0 mL . of 0.10 MCl . In calculating the pH for the final solution, you would make some assumptions about the order in which various reactions occur to simplify the calculations. Sates these assumptions. Does it matter whether the reactions actually occur in the assurned order? Explain.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 10

A certain sodium compound is dissolved in water to liberate $\mathrm{Na}^{+}$ions and a certain negative ion. What evidence would you look for to determine whether the anion is behaving as an acid or a base? How could you tell whether the anion is a strong base? Explain how the anion could behave simultaneously as an acid and a base.

Ronald Prasad

Numerade Educator

Problem 10

Calculate the percentage of pyridine $\left(\mathrm{C}_5 \mathrm{H}_5 \mathrm{~N}\right)$ that forms pyridinium ion, $\mathrm{C}_5 \mathrm{H}_5 \mathrm{NH}^{+}$, in a $0.10-M$ aqueous solution of pyridine $\left(K_{\mathrm{b}}=1.7 \times 10^{-9}\right)$.

James Irizarry

Numerade Educator

Problem 11

Acids and bases can be thought of as chemical opposites (acids are proton donors, and bases are proton acceptors). Therefore, one might think that $K_{\mathrm{a}}=1 / K_{\mathrm{b}}$. Why isn't this the case? What is the relationship between $K_{\mathrm{a}}$ and $K_{\mathrm{b}}$ ? Prove it with a derivation.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 12

Consider two solutions of the salts $\mathrm{NaX}(a q)$ and $\mathrm{NaY}(a q)$ at equal concentrations. What would you need to know to determine which solution has the higher pH ? Explain how you would decide (perhaps even provide a sample calculation).

Eric Ferrara

Numerade Educator

Problem 14

Why is the pH of water at $25^{\circ} \mathrm{C}$ equal to 7.00 ?

Eric Ferrara

Numerade Educator

Problem 15

Can the pH of a solution be negative? Explain.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 15

A 2.14-g sample of sodium hypoiodite is dissolved in water to make 1.25 L of solution. The solution pH is 11.32 . What is $K_{\mathrm{b}}$ for the hypoiodite ion?

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 16

Is the conjugate base of a weak acid a strong base? Explain. Explain why $\mathrm{Cl}^{-}$does not affect the pH of an aqueous solution.

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 16

The equilibrium constant $K_{\mathrm{a}}$ for the reaction
$$
\begin{aligned}
& \mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6{ }^{3+}(a q)+\mathrm{H}_2 \mathrm{O}(l) \rightleftharpoons \\
& \mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_5(\mathrm{OH})^{2+}(a q)+\mathrm{H}_3 \mathrm{O}^{+}(a q) \\
&
\end{aligned}
$$
is $6.0 \times 10^{-3}$.
a. Calculate the pH of a $0.10-\mathrm{M}$ solution of $\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6{ }^{3+}$.
b. Will a $1.0-M$ solution of iron(II) nitrate have a higher or lower pH than a $1.0-\mathrm{M}$ solution of iron(III) nitrate? Explain.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 17

Match the following pH values: $1,2,5,6,6.5,8,11,11$, and 13 with the following chemicals (of equal concentration): $\mathrm{HBr}, \mathrm{NaOH}, \mathrm{NaF}, \mathrm{NaCN}, \mathrm{NH}_4 \mathrm{~F}, \mathrm{CH}_3 \mathrm{NH}_3 \mathrm{~F}, \mathrm{HF}, \mathrm{HCN}$, and $\mathrm{NH}_3$. Answer this question without performing calculations.

Ronald Prasad

Numerade Educator

Problem 17

Calculate the pH of a $0.200-M$ solution of $\mathrm{C}_5 \mathrm{H}_5 \mathrm{NHF}$. Hint: $\mathrm{C}_5 \mathrm{H}_5 \mathrm{NHF}$ is a salt composed of $\mathrm{C}_5 \mathrm{H}_5 \mathrm{NH}^{+}$and $\mathrm{F}^{-}$ions. The principal equilibrium in this solution is the best acid reacting with the best base; the reaction for the principal equilibrium is
$$
\begin{array}{r}
\mathrm{C}_5 \mathrm{H}_5 \mathrm{NH}^{+}(a q)+\mathrm{F}^{-}(a q) \rightleftharpoons \\
\mathrm{C}_5 \mathrm{H}_5 \mathrm{~N}(a q)+\mathrm{HF}(a q) \quad K=8.2 \times 10^{-3}
\end{array}
$$

Ronald Prasad

Numerade Educator

Problem 18

The salt BX, when dissolved in water, produces an acidic solution. Which of the following could be true? (There may be more than one correct answer.)
a. The acid HX is a weak acid.
b. The acid HX is a strong acid.
c. The cation $\mathrm{B}^{+}$is a weak acid.
Explain.

Sima Sarker

Numerade Educator

Problem 18

An aqueous solution contains a mixture of 0.0500 M HCOOH $\left(K_{\mathrm{a}}=1.77 \times 10^{-4}\right)$ and $0.150 \mathrm{M} \mathrm{CH}_3 \mathrm{CH}_2 \mathrm{COOH}$ $\left(K_{\mathrm{a}}=1.34 \times 10^{-5}\right)$. Calculate the pH of this solution. Because both acids are of comparable strength, the $\mathrm{H}^{+}$contribution from both acids must be considered.

James Irizarry

Numerade Educator

Problem 19

19. equations illustrating the amphoterism of these two anions.

Ian Kaigh

Numerade Educator

Problem 20

Which of the following conditions indicate an acidic solution at $25^{\circ} \mathrm{C}$ ?
a. $\mathrm{pH}=3.04$
b. $\left[\mathrm{H}^{+}\right]>1.0 \times 10^{-7} \mathrm{M}$
c. $\mathrm{pOH}=4.51$
d. $\left[\mathrm{OH}^{-}\right]=3.21 \times 10^{-12} \mathrm{M}$

Eric Ferrara

Numerade Educator

Problem 21

Which of the following conditions indicate a basic solution at $25^{\circ} \mathrm{C}$ ?
a. $\mathrm{pOH}=11.21$
b. $\mathrm{pH}=9.42$
c. $\left[\mathrm{OH}^{-}\right]>\left[\mathrm{H}^{+}\right]$
d. $\left[\mathrm{OH}^{-}\right]>1.0 \times 10^{-7} \mathrm{M}$

Ian Kaigh

Numerade Educator

Problem 22

Why is $\mathrm{H}_3 \mathrm{O}^{+}$the strongest acid and $\mathrm{OH}^{-}$the strongest base that can exist in significant amounts in aqueous solutions?

Shahina -

Numerade Educator

Problem 23

How many significant figures are there in the following numbers: $10.78,6.78,0.78$ ? If these were pH values, to how many significant figures can you express the $\left[\mathrm{H}^{+}\right]$? Explain any discrepancies between your answers to the two questions.

Ian Kaigh

Numerade Educator

Problem 24

In terms of orbitals and electron arrangements, what must be present for a molecule or an ion to act as a Lewis acid? What must be present for a molecule or an ion to act as a Lewis base?

Eric Ferrara

Numerade Educator

Problem 25

Consider the autoionization of liquid ammonia:
Label each of the species in the equation as an acid or a base and explain your answer.

Ian Kaigh

Numerade Educator

Problem 26

The following are representations of acid-base reactions:
a. Label each of the species in both equations as an acid or a base and explain your answers.
b. For those species that are acids, which labels apply: Arrhenius acid, Brønsted-Lowry acid, Lewis acid? What about the bases?

Ronald Prasad

Numerade Educator

Problem 27

Give three example solutions that fit each of the following descriptions.
a. a strong electrolyte solution that is very acidic
b. a strong electrolyte solution that is slightly acidic
c. a strong electrolyte solution that is very basic
d. a strong electrolyte solution that is slightly basic
e. a strong electrolyte solution that is neutral

Ian Kaigh

Numerade Educator

Problem 28

Derive an expression for the relationship between $\mathrm{p} K_{\mathrm{a}}$ and $\mathrm{p} K_{\mathrm{b}}$ for a conjugate acid-base pair. ( $\mathrm{p} K=-\log K$.)

Eric Ferrara

Numerade Educator

Problem 29

Consider the following statements. Write out an example reaction and $K$ expression that is associated with each statement.
a. The autoionization of water.
b. An acid reacts with water to produce the conjugate base of the acid and the hydronium ion.
c. A base reacts with water to produce the conjugate acid of the base and the hydroxide ion.

Ronald Prasad

Numerade Educator

Problem 30

Which of the following statements is(are) true? Correct the false statements.
a. When a base is dissolved in water, the lowest possible pH of the solution is 7.0 .
b. When an acid is dissolved in water, the lowest possible pH is 0 .
c. A strong acid solution will have a lower pH than a weak acid solution.
d. A $0.0010-\mathrm{MBa}(\mathrm{OH})_2$ solution has a pOH that is twice the pOH value of a $0.0010-M \mathrm{KOH}$ solution.

Cheryl Glor

Numerade Educator

Problem 31

Consider the following mathematical expressions.
a. $\left[\mathrm{H}^{+}\right]=[\mathrm{HA}]_0$
b. $\left[\mathrm{H}^{+}\right]=\left(K_{\mathrm{a}} \times[\mathrm{HA}]_0\right)^{1 / 2}$
c. $\left[\mathrm{OH}^{-}\right]=2[\mathrm{~B}]_0$
d. $\left[\mathrm{OH}^{-}\right]=\left(K_{\mathrm{b}} \times[\mathrm{B}]_{\mathrm{o}}\right)^{1 / 2}$
For each expression, give three solutions where the mathematical expression would give a good approximation for the $\left[\mathrm{H}^{+}\right]$or $\left[\mathrm{OH}^{-}\right]$. $[\mathrm{HA}]_0$ and $[\mathrm{B}]_0$ represent initial concentrations of an acid or a base.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 32

Consider a $0.10-M \mathrm{H}_2 \mathrm{CO}_3$ solution and a $0.10-M \mathrm{H}_2 \mathrm{SO}_4$ solution. Without doing any detailed calculations, choose one of the following statements that best describes the $\left[\mathrm{H}^{+}\right]$of each solution and explain your answer.
a. The $\left[\mathrm{H}^{+}\right]$is less than 0.10 M .
b. The $\left[\mathrm{H}^{+}\right]$is 0.10 M .
c. The $\left[\mathrm{H}^{+}\right]$is between 0.10 M and 0.20 M .
d. The $\left[\mathrm{H}^{+}\right]$is 0.20 M .

Eric Ferrara

Numerade Educator

Problem 33

Of the hydrogen halides, only HF is a weak acid. Give a possible explanation.

Ibrahim Abdullahi

Ibrahim Abdullahi

Numerade Educator

Problem 35

Write balanced equations that describe the following reactions.
a. the dissociation of perchloric acid in water
b. the dissociation of propanoic acid $\left(\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CO}_2 \mathrm{H}\right)$ in water
c. the dissociation of ammonium ion in water

Ian Kaigh

Numerade Educator

Problem 36

Write the dissociation reaction and the corresponding $K_{\mathrm{a}}$ equilibrium expression for each of the following acids in water.
a. HCN
b. $\mathrm{HOC}_6 \mathrm{H}_5$
c. $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}$

Ronald Prasad

Numerade Educator

Problem 37

For each of the following aqueous reactions, identify the acid, the base, the conjugate base, and the conjugate acid.
a. $\mathrm{H}_2 \mathrm{O}+\mathrm{H}_2 \mathrm{CO}_3 \rightleftharpoons \mathrm{H}_3 \mathrm{O}^{+}+\mathrm{HCO}_3^{-}$
b. $\mathrm{C}_5 \mathrm{H}_5 \mathrm{NH}^{+}+\mathrm{H}_2 \mathrm{O} \rightleftharpoons \mathrm{C}_5 \mathrm{H}_5 \mathrm{~N}+\mathrm{H}_3 \mathrm{O}^{+}$
c. $\mathrm{HCO}_3{ }^{-}+\mathrm{C}_5 \mathrm{H}_5 \mathrm{NH}^{+} \rightleftharpoons \mathrm{H}_2 \mathrm{CO}_3+\mathrm{C}_5 \mathrm{H}_5 \mathrm{~N}$

Nicole Krahulik

Nicole Krahulik

Numerade Educator

Problem 38

For each of the following aqueous reactions, identify the acid, the base, the conjugate base, and the conjugate acid.
a. $\mathrm{Al}\left(\mathrm{H}_2 \mathrm{O}\right)_6{ }^{3+}+\mathrm{H}_2 \mathrm{O} \rightleftharpoons \mathrm{H}_3 \mathrm{O}^{+}+\mathrm{Al}\left(\mathrm{H}_2 \mathrm{O}\right)_5(\mathrm{OH})^{2+}$
b. $\mathrm{H}_2 \mathrm{O}+\mathrm{HONH}_3^{+} \rightleftharpoons \mathrm{HONH}_2+\mathrm{H}_3 \mathrm{O}^{+}$
c. $\mathrm{HOCl}+\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2 \rightleftharpoons \mathrm{OCl}^{-}+\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}$

Eric Ferrara

Numerade Educator

Problem 39

Classify each of the following as a strong acid or a weak acid.
a.
b.
c.
d.
S

Ian Kaigh

Numerade Educator

Problem 40

Consider the following illustrations:
Which beaker best illustrates what happens when the following acids are dissolved in water?
a. $\mathrm{HNO}_2$
d. HF
b. $\mathrm{HNO}_3$
e. $\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2$
c. HCl

Ronald Prasad

Numerade Educator

Problem 41

Use Table 13.2 to order the following from the strongest to the weakest acid.
$$
\begin{array}{llll}
\mathrm{HClO}_2, & \mathrm{H}_2 \mathrm{O}, & \mathrm{NH}_4{ }^{+}, & \mathrm{HClO}_4
\end{array}
$$

Ronald Prasad

Numerade Educator

Problem 42

Use Table 13.2 to order the following from the strongest to the weakest base.
$$
\mathrm{ClO}_2^{-}, \quad \mathrm{H}_2 \mathrm{O}, \quad \mathrm{NH}_3, \quad \mathrm{ClO}_4^{-}
$$

Anish Wadhwa

Numerade Educator

Problem 43

You may need Table 13.2 to answer the following questions.
a. Which is the stronger acid, HCl or $\mathrm{H}_2 \mathrm{O}$ ?
b. Which is the stronger acid, $\mathrm{H}_2 \mathrm{O}$ or $\mathrm{HNO}_2$ ?
c. Which is the stronger acid, HCN or $\mathrm{HOC}_6 \mathrm{H}_5$ ?

Ronald Prasad

Numerade Educator

Problem 44

You may need Table 13.2 to answer the following questions.
a. Which is the stronger base, $\mathrm{Cl}^{-}$or $\mathrm{H}_2 \mathrm{O}$ ?
b. Which is the stronger base, $\mathrm{H}_2 \mathrm{O}$ or $\mathrm{NO}_2^{-}$?
c. Which is the stronger base, $\mathrm{CN}^{-}$or $\mathrm{OC}_6 \mathrm{H}_5^{-}$?

Ronald Prasad

Numerade Educator

Problem 45

Calculate the $\left[\mathrm{OH}^{-}\right]$of each of the following solutions at $25^{\circ} \mathrm{C}$. Identify each solution as neutral, acidic, or basic.
a. $\left[\mathrm{H}^{+}\right]=1.0 \times 10^{-7} \mathrm{M}$
c. $\left[\mathrm{H}^{+}\right]=12 \mathrm{M}$
b. $\left[\mathrm{H}^{+}\right]=8.3 \times 10^{-16} \mathrm{M}$
d. $\left[\mathrm{H}^{+}\right]=5.4 \times 10^{-5} \mathrm{M}$

Ronald Prasad

Numerade Educator

Problem 46

Calculate the $\left[\mathrm{H}^{+}\right]$of each of the following solutions at $25^{\circ} \mathrm{C}$. Identify each solution as neutral, acidic, or basic.
a. $\left[\mathrm{OH}^{-}\right]=1.5 \mathrm{M}$
b. $\left[\mathrm{OH}^{-}\right]=3.6 \times 10^{-15} \mathrm{M}$
c. $\left[\mathrm{OH}^{-}\right]=1.0 \times 10^{-7} \mathrm{M}$
d. $\left[\mathrm{OH}^{-}\right]=7.3 \times 10^{-4} \mathrm{M}$

Nicole Krahulik

Nicole Krahulik

Numerade Educator

Problem 48

At $40 .^{\circ} \mathrm{C}$ the value of $K_{\mathrm{w}}$ is $2.92 \times 10^{-14}$.
a. Calculate the $\left[\mathrm{H}^{+}\right]$and $\left[\mathrm{OH}^{-}\right]$in pure water at $40 .{ }^{\circ} \mathrm{C}$.
b. What is the pH of pure water at $40 .{ }^{\circ} \mathrm{C}$ ?
c. If the hydroxide ion concentration in a solution is 0.10 M , what is the pH at $400^{\circ} \mathrm{C}$ ?

Eric Ferrara

Numerade Educator

Problem 49

Calculate the pH and pOH of the solutions in Exercises 45 and 46 .

David Collins

Numerade Educator

Problem 50

Calculate $\left[\mathrm{H}^{+}\right]$and $\left[\mathrm{OH}^{-}\right]$for each solution at $25^{\circ} \mathrm{C}$. Identify each solution as neutral, acidic, or basic.
a. $\mathrm{pH}=7.40$ (the normal pH of blood)
b. $\mathrm{pH}=15.3$
c. $\mathrm{pH}=-1.0$
d. $\mathrm{pH}=3.20$
e. $\mathrm{pOH}=5.0$
f. $\mathrm{pOH}=9.60$

Ian Kaigh

Numerade Educator

Problem 51

Fill in the missing information in the following table.

$$
\begin{array}{|c|c|c|c|c|c|}
\hline & \mathrm{pH} & \mathrm{pOH} & {\left[\mathrm{H}^{+}\right]} & {\left[\mathrm{OH}^{-}\right]} & \begin{array}{l}
\text { Acidic, } \\
\text { Basic, or } \\
\text { Neutral? }
\end{array} \\
\hline \text { Iution a } & 6.88 & ] & & & \\
\hline \text { Solution b } & & & & 8.4 \times 10^{-14} \mathrm{M} & \\
\hline \text { on } \mathrm{C} & & 3.11 & & & \\
\hline \text { Solution d } & & \square & 1.0 \times 10^{-7} \mathrm{M} & & \\
\hline
\end{array}
$$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 52

Fill in the missing information in the following table.

$$
\begin{array}{|c|c|c|c|c|c|}
\hline & \mathrm{pH} & \mathrm{pOH} & {\left[\mathrm{H}^{+}\right]} & {\left[\mathrm{OH}^{-}\right]} & \begin{array}{l}
\text { Acidic, Basic } \\
\text { or Neutral? }
\end{array} \\
\hline \text { Solution a } & 9.63 & & & & \\
\hline \text { Solution } \mathrm{b} & & & & 3.9 \times 10^{-6} M & \\
\hline \text { Solution c } & & & \underline{0.027 \mathrm{M}} & & \\
\hline \text { Solution d } & \text { _ } & 1.22 & & & \\
\hline
\end{array}
$$

Adriano Chikande

Adriano Chikande

Numerade Educator

Problem 53

The pH of a sample of gastric juice in a person's stomach is 2.1. Calculate the $\mathrm{pOH},\left[\mathrm{H}^{+}\right]$, and $\left[\mathrm{OH}^{-}\right]$for this sample. Is gastric juice acidic or basic?

Ronald Prasad

Numerade Educator

Problem 54

The pOH of a sample of baking soda dissolved in water is 5.74 at $25^{\circ} \mathrm{C}$. Calculate the $\mathrm{pH},\left[\mathrm{H}^{+}\right]$, and $\left[\mathrm{OH}^{-}\right]$for this sample. Is the solution acidic or basic?

Eric Ferrara

Numerade Educator

Problem 55

What are the major species present in 0.250 M solutions of each of the following acids? Calculate the pH of each of these solutions.
a. $\mathrm{HClO}_4$
b. $\mathrm{HNO}_3$

Ronald Prasad

Numerade Educator

Problem 56

A solution is prepared by adding 50.0 mL of 0.050 M HBr to 150.0 mL of 0.10 M HI . Calculate $\left[\mathrm{H}^{+}\right]$and the pH of this solution. HBr and HI are both considered strong acids.

Eric Ferrara

Numerade Educator

Problem 57

Calculate the pH of each of the following solutions of a strong acid in water.
a. 0.10 MHCl
c. $1.0 \times 10^{-11} \mathrm{MHCl}$
b. 5.0 M HCl

Sima Sarker

Numerade Educator

Problem 58

Calculate the pH of each of the following solutions containing a strong acid in water.
a. $2.0 \times 10^{-2} \mathrm{MHNO}_3$
c. $6.2 \times 10^{-12} \mathrm{MHNO}_3$
b. $4.0 \mathrm{M} \mathrm{HNO}_3$

Sima Sarker

Numerade Educator

Problem 59

Calculate the concentration of an aqueous HI solution that has $\mathrm{pH}=2.50 . \mathrm{HI}$ is a strong acid.

Vishal Sharma

Numerade Educator

Problem 60

Calculate the concentration of an aqueous HBr solution that has $\mathrm{pH}=4.25 . \mathrm{HBr}$ is a strong acid.

Ian Kaigh

Numerade Educator

Problem 61

How would you prepare 1600 mL of a $\mathrm{pH}=1.50$ solution using concentrated ( 12 M$) \mathrm{HCl}$ ?

Ian Kaigh

Numerade Educator

Problem 62

A solution is prepared by adding 50.0 mL concentrated hydrochloric acid and 20.0 mL concentrated nitric acid to 300 mL water. More water is added until the final volume is 1.00 L . Calculate $\left[\mathrm{H}^{+}\right],\left[\mathrm{OH}^{-}\right]$, and the pH for this solution. [Hint: Concentrated HCl is $38 \% \mathrm{HCl}$ (by mass) and has a density of $1.19 \mathrm{~g} / \mathrm{mL}$; concentrated $\mathrm{HNO}_3$ is $70 . \% \mathrm{HNO}_3$ (by mass) and has a density of $1.42 \mathrm{~g} / \mathrm{mL}$.]

Eric Ferrara

Numerade Educator

Problem 63

What are the major species present in 0.250 M solutions of each of the following acids? Calculate the pH of each of these solutions.
a. $\mathrm{HNO}_2$
b. $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}\left(\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2\right)$

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 64

What are the major species present in 0.250 M solutions of each of the following acids? Calculate the pH of each of these solutions.
a. $\mathrm{HOC}_6 \mathrm{H}_3$
b. HCN

Ronald Prasad

Numerade Educator

Problem 65

Calculate the concentration of all species present and the pH of a $0.020-M \mathrm{HF}$ solution.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 66

Calculate the percent dissociation for a $0.22-M$ solution of chlorous acid $\left(\mathrm{HClO}_2, K_{\mathrm{u}}=1.2 \times 10^{-2}\right)$.

Ronald Prasad

Numerade Educator

Problem 67

For propanoic acid $\left(\mathrm{HC}_3 \mathrm{H}_5 \mathrm{O}_2, K_{\mathrm{a}}=1.3 \times 10^{-5}\right)$, determine the concentration of all species present, the pH , and the percent dissociation of a $0.100-M$ solution.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 68

A solution is prepared by dissolving 0.56 g benzoic acid $\left(\mathrm{C}_6 \mathrm{H}_5 \mathrm{CO}_2 \mathrm{H}, K_{\mathrm{a}}=6.4 \times 10^{-5}\right)$ in enough water to make 1.0 L of solution. Calculate $\left[\mathrm{C}_6 \mathrm{H}_5 \mathrm{CO}_2 \mathrm{H}\right],\left[\mathrm{C}_6 \mathrm{H}_5 \mathrm{CO}_2^{-}\right],\left[\mathrm{H}^{+}\right],\left[\mathrm{OH}^{-}\right]$, and the pH of this solution.

James Irizarry

Numerade Educator

Problem 69

Monochloroacetic acid, $\mathrm{HC}_2 \mathrm{H}_2 \mathrm{ClO}_2$, is a skin irritant that is used in "chemical peels" intended to remove the top layer of dead skin from the face and ultimately improve the complexion. The value of $K_{\mathrm{a}}$ for monochloroacetic acid is $1.35 \times 10^{-3}$. Calculate the pH of a $0.10-\mathrm{M}$ solution of monochloroacetic acid.

James Irizarry

Numerade Educator

Problem 70

A typical aspirin tablet contains 325 mg acetylsalicylic acid $\left(\mathrm{HC}_9 \mathrm{H}_7 \mathrm{O}_4\right)$. Calculate the pH of a solution that is prepared by dissolving two aspirin tablets in enough water to make one cup ( 237 mL ) of solution. Assume the aspirin tablets are pure acetylsalicylic acid, $K_{\mathrm{a}}=3.3 \times 10^{-4}$.

Ian Kaigh

Numerade Educator

Problem 71

Calculate the pH of a solution that contains 1.0 MF and $1.0 \mathrm{M} \mathrm{HOC}_6 \mathrm{H}_5$. Also calculate the concentration of $\mathrm{OC}_6 \mathrm{H}_5^{-}$ in this solution at equilibrium.

Ronald Prasad

Numerade Educator

Problem 72

A solution is made by adding 50.0 mL of 0.200 M acetic acid $\left(K_{\mathrm{a}}=1.8 \times 10^{-5}\right.$ ) to 50.0 mL of $1.00 \times 10^{-3} \mathrm{M} \mathrm{HCl}$.
a. Calculate the pH of the solution.
b. Calculate the acetate ion concentration.

Ronald Prasad

Numerade Educator

Problem 73

Calculate the percent dissociation of the acid in each of the following solutions.
a. 0.50 M acetic acid
b. 0.050 M acetic acid
c. 0.0050 M acetic acid
d. Use Le Châtelier's principle to explain why percent dissociation increases as the concentration of a weak acid decreases.
e. Even though the percent dissociation increases from solutions a to c , the $\left[\mathrm{H}^{+}\right]$decreases. Explain.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 74

Using the $K_{\mathrm{a}}$ values in Table 13.2, calculate the percent dissociation in a $0.20-M$ solution of each of the following acids.
a. nitric acid $\left(\mathrm{HNO}_3\right)$
b. nitrous acid $\left(\mathrm{HNO}_2\right)$
c. phenol $\left(\mathrm{HOC}_6 \mathrm{H}_5\right)$
d. How is percent dissociation of an acid related to the $K_{\mathrm{a}}$ value for the acid (assuming equal initial concentrations of acids)?

David Collins

Numerade Educator

Problem 75

A $0.15-M$ solution of a weak acid is $3.0 \%$ dissociated. Calculate $K_a$.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 76

An acid HX is $25 \%$ dissociated in water. If the equilibrium concentration of HX is 0.30 M , calculate the $K_{\mathrm{a}}$ value for HX .

James Irizarry

Numerade Educator

Problem 77

Trichloroacetic acid $\left(\mathrm{CCl}_3 \mathrm{CO}_2 \mathrm{H}\right)$ is a corrosive acid that is used to precipitate proteins. The pH of a $0.050-M$ solution of trichloroacetic acid is the same as the pH of a $0.040-\mathrm{M} \mathrm{HClO}_4$ solution. Calculate $K_{\mathrm{a}}$ for trichloroacetic acid.

Sima Sarker

Numerade Educator

Problem 78

The pH of a $0.063-M$ solution of hypobromous acid $(\mathrm{HOBr}$ but usually written HBrO ) is 4.95 . Calculate $K_{\mathrm{a}}$.

James Irizarry

Numerade Educator

Problem 80

A typical sample of vinegar has a pH of 3.0 . Assuming that vinegar is only an aqueous solution of acetic acid $\left(K_{\mathrm{a}}=1.8 \times 10^{-5}\right)$, calculate the concentration of acetic acid in vinegar.

Ronald Prasad

Numerade Educator

Problem 81

One mole of a weak acid HA was dissolved in 2.0 L of solution. After the system had come to equilibrium, the concentration of HA was found to be 0.45 M . Calculate $K_{\mathrm{a}}$ for HA.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 82

You have 100.0 g saccharin, a sugar substitute, and you want to prepare a $\mathrm{pH}=5.75$ solution. What volume of solution can be prepared? For saccharin, $\mathrm{HC}_7 \mathrm{H}_4 \mathrm{NSO}_3, \mathrm{p} K_{\mathrm{a}}=11.70$ $\left(\mathrm{p} K_{\mathrm{a}}=-\log K_{\mathrm{a}}\right)$.

Ronald Prasad

Numerade Educator

Problem 83

Write the reaction and the corresponding $K_{\mathrm{b}}$ equilibrium expression for each of the following substances acting as bases in water.
a. $\mathrm{NH}_3$
b. $\mathrm{C}_5 \mathrm{H}_5 \mathrm{~N}$

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 84

Write the reaction and the corresponding $K_{\mathrm{b}}$ equilibrium expression for each of the following substances acting as bases in water.
a. aniline, $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2$
b. dimethylamine, $\left(\mathrm{CH}_3\right)_2 \mathrm{NH}$

James Irizarry

Numerade Educator

Problem 85

Use Table 13.3 to help order the following bases from strongest to weakest.
$$
\mathrm{NO}_3{ }^{-}, \quad \mathrm{H}_2 \mathrm{O}, \quad \mathrm{NH}_3, \quad \mathrm{C}_5 \mathrm{H}_5 \mathrm{~N}
$$

Ronald Prasad

Numerade Educator

Problem 86

Use Table 13.3 to help order the following acids from strongest to weakest.
$$
\mathrm{HNO}_3, \quad \mathrm{H}_2 \mathrm{O}, \quad \mathrm{NH}_4{ }^{+}, \quad \mathrm{C}_5 \mathrm{H}_5 \mathrm{NH}^{+}
$$

Ronald Prasad

Numerade Educator

Problem 87

Use Table 13.3 to help answer the following questions.
a. Which is the stronger base, $\mathrm{ClO}_4{ }^{-}$or $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2$ ?
b. Which is the stronger base, $\mathrm{H}_2 \mathrm{O}$ or $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2$ ?
c. Which is the stronger base, $\mathrm{OH}^{-}$or $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2$ ?
d. Which is the stronger base, $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2$ or $\mathrm{CH}_3 \mathrm{NH}_2$ ?

Ronald Prasad

Numerade Educator

Problem 88

Use Table 13.3 to help answer the following questions.
a. Which is the stronger acid, $\mathrm{HClO}_4$ or $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}$?
b. Which is the stronger acid, $\mathrm{H}_2 \mathrm{O}$ or $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}$?
c. Which is the stronger acid, $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}$or $\mathrm{CH}_3 \mathrm{NH}_3{ }^{+}$?

Ronald Prasad

Numerade Educator

Problem 89

Calculate the pH of the following solutions.
a. 0.10 M NaOH
b. $1.0 \times 10^{-10} \mathrm{M} \mathrm{NaOH}$
c. 2.0 M NaOH

Nicole Krahulik

Nicole Krahulik

Numerade Educator

Problem 90

Calculate $\left[\mathrm{OH}^{-}\right], \mathrm{pOH}$, and pH for each of the following.
a. $0.00040 \mathrm{M} \mathrm{Ca}(\mathrm{OH})_2$
b. a solution containing 25 g KOH per liter
c. a solution containing 150.0 g NaOH per liter

Cheryl Glor

Numerade Educator

Problem 91

What are the major species present in 0.015 M solutions of each of the following bases?
a. KOH
b. $\mathrm{Ba}(\mathrm{OH})_2$
What is $\left[\mathrm{OH}^{-}\right]$and the pH of each of these solutions?

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 92

What are the major species present in the following mixtures of bases?
a. 0.050 M NaOH and 0.050 MLiOH
b. $0.0010 \mathrm{M} \mathrm{Ca}(\mathrm{OH})_2$ and 0.020 M RbOH
What is $\left[\mathrm{OH}^{-}\right]$and the pH of each of these solutions?

Ronald Prasad

Numerade Educator

Problem 93

What mass of KOH is necessary to prepare 800.0 mL of a solution having a $\mathrm{pH}=11.56$ ?

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 94

Calculate the concentration of an aqueous $\mathrm{Sr}(\mathrm{OH})_2$ that has $\mathrm{pH}=10.50$.

James Irizarry

Numerade Educator

Problem 95

What are the major species present in a $0.150-M \mathrm{NH}_3$ solution? Calculate the $\left[\mathrm{OH}^{-}\right]$and the pH of this solution.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 96

For the reaction of hydrazine $\left(\mathrm{N}_2 \mathrm{H}_4\right)$ in water,
$$
\mathrm{H}_2 \mathrm{NNH}_2(a q)+\mathrm{H}_2 \mathrm{O}(l) \rightleftharpoons \mathrm{H}_2 \mathrm{NNH}_3{ }^{+}(a q)+\mathrm{OH}^{-}(a q)
$$
$K_{\mathrm{b}}$ is $3.0 \times 10^{-6}$. Calculate the concentrations of all species and the pH of a $2.0-M$ solution of hydrazine in water.

James Irizarry

Numerade Educator

Problem 97

Calculate $\left[\mathrm{OH}^{-}\right],\left[\mathrm{H}^{+}\right]$, and the pH of 0.20 M solutions of each of the following amines.
a. triethylamine $\left[\left(\mathrm{C}_2 \mathrm{H}_5\right)_3 \mathrm{~N}, K_{\mathrm{b}}=4.0 \times 10^{-4}\right]$
b. hydroxylamine $\left(\mathrm{HONH}_2, K_{\mathrm{b}}=1.1 \times 10^{-8}\right)$

Ronald Prasad

Numerade Educator

Problem 98

Calculate $\left[\mathrm{OH}^{-}\right],\left[\mathrm{H}^{+}\right]$, and the pH of 0.40 M solutions of each of the following amines (the $K_{\mathrm{b}}$ values are found in Table 13.3).
a. aniline
b. methylamine

Ronald Prasad

Numerade Educator

Problem 99

Calculate the pH of a $0.20-M \quad \mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2$ solution $\left(K_{\mathrm{b}}=5.6 \times 10^{-4}\right)$.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 100

Calculate the pH of a $0.050-\mathrm{M}\left(\mathrm{C}_2 \mathrm{H}_5\right)_2 \mathrm{NH}$ solution $\left(K_{\mathrm{b}}=1.3 \times 10^{-3}\right)$.

James Irizarry

Numerade Educator

Problem 101

What is the percent ionization in each of the following solutions?
a. $0.10 \mathrm{MH}_3$
c. $0.10 \mathrm{M} \mathrm{CH}_3 \mathrm{NH}_2$
b. $0.010 \mathrm{MH}_3$

Ronald Prasad

Numerade Educator

Problem 103

The pH of a $0.016-M$ aqueous solution of $p$-toluidine $\left(\mathrm{CH}_3 \mathrm{C}_6 \mathrm{H}_4 \mathrm{NH}_2\right)$ is 8.60. Calculate $K_{\mathrm{b}}$.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 104

Calculate the mass of $\mathrm{HONH}_2$ required to dissolve in enough water to make 250.0 mL of solution having a pH of $10.00\left(K_{\mathrm{b}}=\right.$ $1.1 \times 10^{-8}$.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 105

Write out the stepwise $K_{\mathrm{a}}$ reactions for the diprotic acid $\mathrm{H}_2 \mathrm{SO}_3$.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 106

Write out the stepwise $K_2$ reactions for citric acid $\left(\mathrm{H}_3 \mathrm{C}_6 \mathrm{H}_5 \mathrm{O}_7\right)$, a triprotic acid.

James Irizarry

Numerade Educator

Problem 107

A typical vitamin C tablet (containing pure ascorbic acid, $\mathrm{H}_2 \mathrm{C}_6 \mathrm{H}_6 \mathrm{O}_6$ ) weighs 500 . mg. One vitamin C tablet is dissolved in enough water to make 200.0 mL of solution. Calculate the pH of this solution. Ascorbic acid is a diprotic acid.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 108

Arsenic acid $\left(\mathrm{H}_3 \mathrm{AsO}_4\right)$ is a triprotic acid with $K_{a_1}=5.5 \times 10^{-3}$, $K_{\mathrm{a}_1}=1.7 \times 10^{-7}$, and $K_{\mathrm{a}_3}=5.1 \times 10^{-12}$. Calculate $\left[\mathrm{H}^{+}\right]$, $\left[\mathrm{OH}^{-}\right],\left[\mathrm{H}_3 \mathrm{AsO}_4\right],\left[\mathrm{H}_2 \mathrm{AsO}_4^{-}\right],\left[\mathrm{HAsO}_4{ }^{2-}\right]$, and $\left[\mathrm{AsO}_4{ }^{3-}\right]$ in a $0.20-M$ arsenic acid solution.

James Irizarry

Numerade Educator

Problem 109

Calculate the pH and $\left[\mathrm{S}^{2-}\right]$ in a $0.10-\mathrm{H}_2 \mathrm{~S}$ solution. Assume $K_{\mathrm{a}_1}=1.0 \times 10^{-7} ; K_{\mathrm{a}_2}=1.0 \times 10^{-19}$.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 110

Calculate $\left[\mathrm{CO}_3^{2-}\right]$ in a $0.010-M$ solution of $\mathrm{CO}_2$ in water (usually written as $\mathrm{H}_2 \mathrm{CO}_3$ ). If all the $\mathrm{CO}_3{ }^{2-}$ in this solution comes from the reaction
$$
\mathrm{HCO}_3{ }^{-}(a q) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{CO}_3{ }^{2-}(a q)
$$
what percentage of the $\mathrm{H}^{+}$ions in the solution is a result of the dissociation of $\mathrm{HCO}_3{ }^{-}$? When acid is added to a solution of sodium hydrogen carbonate $\left(\mathrm{NaHCO}_3\right)$, vigorous bubbling occurs. How is this reaction related to the existence of carbonic acid $\left(\mathrm{H}_2 \mathrm{CO}_3\right)$ molecules in aqueous solution?

James Irizarry

Numerade Educator

Problem 111

Calculate the pH of a $2.0-M \mathrm{H}_2 \mathrm{SO}_4$ solution.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 112

Calculate the pH of a $5.0 \times 10^{-3}-M$ solution of $\mathrm{H}_2 \mathrm{SO}_4$.

James Irizarry

Numerade Educator

Problem 113

Arrange the following 0.10 M solutions in order of most acidic to most basic.
$$
\mathrm{KOH}, \quad \mathrm{KNO}_3, \quad \mathrm{KCN}, \quad \mathrm{NH}_4 \mathrm{Cl}, \quad \mathrm{HCl}
$$

Sima Sarker

Numerade Educator

Problem 114

Arrange the following 0.10 M solutions in order from most acidic to most basic. See Appendix 5 for $K_{\mathrm{a}}$ and $K_{\mathrm{b}}$ values.

James Irizarry

Numerade Educator

Problem 115

Given that the $K_{\mathrm{a}}$ value for acetic acid is $1.8 \times 10^{-5}$ and the $K_{\mathrm{a}}$ value for hypochlorous acid is $3.5 \times 10^{-8}$, which is the stronger base, $\mathrm{OCl}^{-}$or $\mathrm{C}_2 \mathrm{H}_3 \mathrm{O}_2^{-}$?

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 116

The $K_{\mathrm{b}}$ values for ammonia and methylamine are $1.8 \times 10^{-5}$ and $4.4 \times 10^{-4}$, respectively. Which is the stronger acid, $\mathrm{NH}_4{ }^{+}$ or $\mathrm{CH}_3 \mathrm{NH}_3{ }^{+}$?

James Irizarry

Numerade Educator

Problem 117

Determine $\left[\mathrm{OH}^{-}\right],\left[\mathrm{H}^{+}\right]$, and the pH of each of the following solutions.
a. 1.0 M KCl
b. $1.0 \mathrm{MKC} \mathrm{KC}_2 \mathrm{H}_3 \mathrm{O}_2$

David Collins

Numerade Educator

Problem 118

Calculate the concentrations of all species present in a $0.25-M$ solution of ethylammonium chloride $\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_3 \mathrm{Cl}\right)$.

James Irizarry

Numerade Educator

Problem 119

Calculate the pH of each of the following solutions.
a. $0.10 \mathrm{MCH}_3 \mathrm{NH}_3 \mathrm{Cl}$
b. 0.050 M NaCN

David Collins

Numerade Educator

Problem 120

Calculate the pH of each of the following solutions.
a. 0.12 MKNO
c. $0.40 \mathrm{MNH}_4 \mathrm{ClO}_4$
b. 0.45 MNaOCl

David Collins

Numerade Educator

Problem 121

Sodium azide $\left(\mathrm{NaN}_3\right)$ is sometimes added to water to kill bacteria. Calculate the concentration of all species in a $0.010-M$ solution of $\mathrm{NaN}_3$. The $K_{\mathrm{a}}$ value for hydrazoic acid $\left(\mathrm{HN}_3\right)$ is $1.9 \times 10^{-5}$.

Sima Sarker

Numerade Educator

Problem 122

Papaverine hydrochloride (abbreviated $\mathrm{papH}^{+} \mathrm{Cl}^{-}$; molar mass $=378.85 \mathrm{~g} / \mathrm{mol}$ ) is a drug that belongs to a group of medicines called vasodilators, which cause blood vessels to expand, thereby increasing blood flow. This drug is the conjugate acid of the weak base papaverine (abbreviated pap; $K_{\mathrm{b}}=$ $8.33 \times 10^{-9}$ at $35.0^{\circ} \mathrm{C}$ ). Calculate the pH of a $30.0-\mathrm{mg} / \mathrm{mL}$ aqueous dose of $\mathrm{papH}^{+} \mathrm{Cl}^{-}$prepared at $35.0^{\circ} \mathrm{C}$. $K_{\mathrm{w}}$ at $35.0^{\circ} \mathrm{C}$ is $2.1 \times 10^{-14}$.

James Irizarry

Numerade Educator

Problem 123

An unknown salt is either $\mathrm{NaCN}, \mathrm{NaC}_2 \mathrm{H}_3 \mathrm{O}_2, \mathrm{NaF}, \mathrm{NaCl}$, or NaOCl . When 0.100 mole of the salt is dissolved in 1.00 L of solution, the pH of the solution is 8.07 . What is the identity of the salt?

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 124

Consider a solution of an unknown salt having the general formula BHCl , where B is one of the weak bases in Table 13.3. A $0.10-M$ solution of the unknown salt has a pH of 5.82 . What is the actual formula of the salt?

Hailey Tomashek

Hailey Tomashek

Numerade Educator

Problem 125

A $0.050-M$ solution of the salt NaB has a pH of 9.00 . Calculate the pH of a $0.010-M$ solution of HB .

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 126

A $0.20-M$ sodium chlorobenzoate $\left(\mathrm{NaC}_7 \mathrm{H}_4 \mathrm{ClO}_2\right)$ solution has a pH of 8.65. Calculate the pH of a $0.20-\mathrm{M}$ chlorobenzoic acid $\left(\mathrm{HC}_7 \mathrm{H}_4 \mathrm{ClO}_2\right)$ solution.

Ronald Prasad

Numerade Educator

Problem 127

Calculate the pH of a $0.050-\mathrm{MAl}\left(\mathrm{NO}_3\right)_3$ solution. The $K_{\mathrm{a}}$ value for $\mathrm{Al}\left(\mathrm{H}_2 \mathrm{O}\right)_6{ }^{3+}$ is $1.4 \times 10^{-5}$.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 128

Calculate the pH of $\mathrm{a} 0.10-\mathrm{M} \mathrm{CoCl}_3$ solution. The $K_{\mathrm{a}}$ value for $\mathrm{Co}\left(\mathrm{H}_2 \mathrm{O}\right)_6{ }^{3+}$ is $1.0 \times 10^{-5}$.

James Irizarry

Numerade Educator

Problem 129

Are solutions of the following salts acidic, basic, or neutral? For those that are not neutral, write balanced chemical equations for the reactions causing the solution to be acidic or basic. The relevant $K_{\mathrm{a}}$ and $K_{\mathrm{b}}$ values are found in Tables 13.2 and 13.3 .
a. $\mathrm{NaNO}_3$
c. $\mathrm{C}_5 \mathrm{H}_5 \mathrm{NHClO}_4$
e. KOCl
b. $\mathrm{NaNO}_2$
d. $\mathrm{NH}_4 \mathrm{NO}_2$
f. $\mathrm{NH}_4 \mathrm{OCl}$

Anand Jangid

Numerade Educator

Problem 130

Are solutions of the following salts acidic, basic, or neutral? For those that are not neutral, write balanced equations for the reactions causing the solution to be acidic or basic. The relevant $K_{\mathrm{a}}$ and $K_{\mathrm{b}}$ values are found in Tables 13.2 and 13.3.
a. $\mathrm{Sr}\left(\mathrm{NO}_3\right)_2$
c. $\mathrm{CH}_3 \mathrm{NH}_3 \mathrm{Cl}$
e. $\mathrm{NH}_4 \mathrm{~F}$
b. $\mathrm{NH}_4 \mathrm{C}_2 \mathrm{H}_3 \mathrm{O}_2$
d. $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3 \mathrm{ClO}_2$
f. $\mathrm{CH}_3 \mathrm{NH}_3 \mathrm{CN}$

Ronald Prasad

Numerade Educator

Problem 131

Place the species in each of the following groups in order of increasing acid strength. Explain the order you chose for each group.
a. $\mathrm{HIO}_3, \mathrm{HBrO}_3$
c. $\mathrm{HOCl}, \mathrm{HOI}$
b. $\mathrm{HNO}_2, \mathrm{HNO}_3$
d. $\mathrm{H}_3 \mathrm{PO}_4, \mathrm{H}_3 \mathrm{PO}_3$

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 132

Place the species in each of the following groups in order of increasing base strength. Give your reasoning in each case.
a. $\mathrm{IO}_3{ }^{-}, \mathrm{BrO}_3{ }^{-}$
b. $\mathrm{NO}_2{ }^{-}, \mathrm{NO}_3{ }^{-}$
c. $\mathrm{OCl}^{-}, \mathrm{OI}^{-}$

James Irizarry

Numerade Educator

Problem 133

Place the species in each of the following groups in order of increasing acid strength.
a. $\mathrm{H}_2 \mathrm{O}, \mathrm{H}_2 \mathrm{~S}, \mathrm{H}_2 \mathrm{Se}$ (bond energies: $\mathrm{H}-\mathrm{O}, 467 \mathrm{~kJ} / \mathrm{mol}$; $\mathrm{H}-\mathrm{S}, 363 \mathrm{~kJ} / \mathrm{mol} ; \mathrm{H}-\mathrm{Se}, 276 \mathrm{~kJ} / \mathrm{mol}$ )
b. $\mathrm{CH}_3 \mathrm{CO}_2 \mathrm{H}, \mathrm{FCH}_2 \mathrm{CO}_2 \mathrm{H}, \mathrm{F}_2 \mathrm{CHCO}_2 \mathrm{H}, \mathrm{F}_3 \mathrm{CCO}_2 \mathrm{H}$
c. $\mathrm{NH}_4{ }^{+}, \mathrm{HONH}_3{ }^{+}$
d. $\mathrm{NH}_4{ }^{+}, \mathrm{PH}_4{ }^{+}$(bond energies: $\mathrm{N}-\mathrm{H}, 391 \mathrm{~kJ} / \mathrm{mol} ; \mathrm{P}-\mathrm{H}$, $322 \mathrm{~kJ} / \mathrm{mol}$ )
Give reasons for the orders you chose.

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 134

Using your results from Exercise 133, place the species in each of the following groups in order of increasing base strength.
a. $\mathrm{OH}^{-}, \mathrm{SH}^{-}, \mathrm{SeH}^{-}$
b. $\mathrm{NH}_3, \mathrm{PH}_3$
c. $\mathrm{NH}_3, \mathrm{HONH}_2$

James Irizarry

Numerade Educator

Problem 135

Will the following oxides give acidic, basic, or neutral solutions when dissolved in water? Write reactions to justify your answers.
a. CaO
b. $\mathrm{SO}_2$
c. $\mathrm{Cl}_2 \mathrm{O}$

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 136

Will the following oxides give acidic, basic, or neutral solutions when dissolved in water? Write reactions to justify your answers.
a. $\mathrm{Li}_2 \mathrm{O}$
b. $\mathrm{CO}_2$
c. SrO

James Irizarry

Numerade Educator

Problem 137

Identify the Lewis acid and the Lewis base in each of the following reactions.
a. $\mathrm{B}(\mathrm{OH})_3(a q)+\mathrm{H}_2 \mathrm{O}(l) \rightleftharpoons \mathrm{B}(\mathrm{OH})_4^{-}(a q)+\mathrm{H}^{+}(a q)$
b. $\mathrm{Ag}^{+}(a q)+2 \mathrm{NH}_3(a q) \rightleftharpoons \mathrm{Ag}\left(\mathrm{NH}_3\right)_2^{+}(a q)$
c. $\mathrm{BF}_3(g)+\mathrm{F}^{-}(a q) \rightleftharpoons \mathrm{BF}_4^{-}(a q)$

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 138

Identify the Lewis acid and the Lewis base in each of the following reactions.
a. $\mathrm{Fe}^{3+}(a q)+6 \mathrm{H}_2 \mathrm{O}(l) \rightleftharpoons \mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6{ }^{3+}(a q)$
b. $\mathrm{H}_2 \mathrm{O}(l)+\mathrm{CN}^{-}(a q) \rightleftharpoons \mathrm{HCN}(a q)+\mathrm{OH}^{-}(a q)$
c. $\mathrm{HgI}_2(s)+2 \mathrm{I}^{-}(a q) \rightleftharpoons \mathrm{HgI}_4{ }^{2-}(a q)$

Anand Jangid

Numerade Educator

Problem 139

Aluminum hydroxide is an amphoteric substance. It can act as either a Brønsted-Lowry base or a Lewis acid. Write a reaction showing $\mathrm{Al}(\mathrm{OH})_3$ acting as a base toward $\mathrm{H}^{+}$and as an acid toward $\mathrm{OH}^{-}$.

Ronald Prasad

Numerade Educator

Problem 140

Zinc hydroxide is an amphoteric substance. Write equations that describe $\mathrm{Zn}(\mathrm{OH})_2$ acting as a Bronsted-Lowry base toward $\mathrm{H}^{+}$and as a Lewis acid toward $\mathrm{OH}^{-}$.

James Irizarry

Numerade Educator

Problem 141

Would you expect $\mathrm{Fe}^{3+}$ or $\mathrm{Fe}^{2+}$ to be the stronger Lewis acid? Explain.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 142

Use the Lewis acid-base model to explain the following reaction.
$$
\mathrm{CO}_2(g)+\mathrm{H}_2 \mathrm{O}(l) \longrightarrow \mathrm{H}_2 \mathrm{CO}_3(a q)
$$

James Irizarry

Numerade Educator

Problem 143

A $10.0-\mathrm{mL}$ sample of an HCl solution has a pH of 2.000 . What volume of water must be added to change the pH to 4.000 ?

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 144

Which of the following represent conjugate acid-base pairs? For those pairs that are not conjugates, write the correct conjugate acid or base for each species in the pair.
a. $\mathrm{H}_2 \mathrm{O}, \mathrm{OH}^{-}$
c. $\mathrm{H}_3 \mathrm{PO}_4, \mathrm{H}_2 \mathrm{PO}_4^{-}$
b. $\mathrm{H}_2 \mathrm{SO}_4, \mathrm{SO}_4{ }^{2-}$
d. $\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2, \mathrm{C}_2 \mathrm{H}_3 \mathrm{O}_2^{-}$

Sima Sarker

Numerade Educator

Problem 145

For solutions of the same concentration, as acid strength increases, indicate what happens to each of the following (increases, decreases, or doesn't change).
a. $\left[\mathrm{H}^{+}\right]$
d. pOH
b. pH
e. $K_{\mathrm{a}}$
c. $\left[\mathrm{OH}^{-}\right]$

Ronald Prasad

Numerade Educator

Problem 146

Complete the table for each of the following solutions:
$$
\begin{array}{|c|c|c|c|c|}
\hline & {\left[\mathrm{H}^{+}\right]} & \mathrm{pH} & \mathrm{pOH} & {\left[\mathrm{OH}^{-}\right]} \\
\hline 0.0070 \mathrm{MHNO}_3 & & & & \\
\hline 3.0 \mathrm{M} \mathrm{KOH} & \text { - } & & & 工 \\
\hline
\end{array}
$$

Sima Sarker

Numerade Educator

Problem 147

Consider a $0.60-\mathrm{M}$ solution of $\mathrm{HC}_3 \mathrm{H}_5 \mathrm{O}_3$, lactic acid ( $K_{\mathrm{a}}=$ $1.4 \times 10^{-4}$ ).
a. Which of the following are major species in the solution?
i. $\mathrm{HC}_3 \mathrm{H}_5 \mathrm{O}_3$
ii. $\mathrm{C}_3 \mathrm{H}_5 \mathrm{O}_3^{-}$
iii. $\mathrm{H}^{+}$
iv. $\mathrm{H}_2 \mathrm{O}$
v. $\mathrm{OH}^{-}$
b. Complete the following ICE table in terms of $x$, the amount ( $\mathrm{mol} / \mathrm{L}$ ) of lactic acid that dissociates to reach equilibrium.

$$
\begin{array}{llll}
& {\left[\mathrm{HC}_3 \mathrm{H}_5 \mathrm{O}_3\right]} & {\left[\mathrm{H}^{+}\right]} & {\left[\mathrm{C}_3 \mathrm{H}_5 \mathrm{O}_3^{-}\right]} \\
\hline \text { Initial } & - & - & \\
\text { Change } & - & - & \\
\text { Equilibrium } & 0.60-x & - & \\
\hline
\end{array}
$$

c. What is the equilibrium concentration for $\mathrm{C}_3 \mathrm{H}_5 \mathrm{O}_3^{-}$?
d. Calculate the pH of the solution.

Ronald Prasad

Numerade Educator

Problem 148

Consider a $0.67-M$ solution of $\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2\left(K_{\mathrm{b}}=5.6 \times 10^{-4}\right)$.
a. Which of the following are major species in the solution?
i. $\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_2$
ii. $\mathrm{H}^{+}$
iii. $\mathrm{OH}^{-}$
iv. $\mathrm{H}_2 \mathrm{O}$
v. $\mathrm{C}_2 \mathrm{H}_5 \mathrm{NH}_3{ }^{+}$
b. Calculate the pH of this solution.

Ronald Prasad

Numerade Educator

Problem 149

Rank the following 0.10 M solutions in order of increasing pH .
a. $\mathrm{NH}_3$
d. KCl
b. KOH
e. HCl
c. $\mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2$

Ronald Prasad

Numerade Educator

Problem 150

Consider 0.25 M solutions of the following salts: NaCl , $\mathrm{RbOCl}, \mathrm{KI}, \mathrm{Ba}\left(\mathrm{ClO}_4\right)_2$, and $\mathrm{NH}_4 \mathrm{NO}_3$. For each salt, indicate whether the solution is acidic, basic, or neutral.

Sima Sarker

Numerade Educator

Problem 152

A solution is tested for pH and conductivity as pictured below:
The solution contains one of the following substances: HCl , $\mathrm{NaOH}, \mathrm{NH}_4 \mathrm{Cl}, \mathrm{HCN}, \mathrm{NH}_3, \mathrm{HF}$, or NaCN . If the solute concentration is about 1.0 M , what is the identity of the solute?

Ronald Prasad

Numerade Educator

Problem 153

Consider 0.10 M solutions of the following compounds: $\mathrm{AlCl}_3$, $\mathrm{NaCN}, \mathrm{KOH}, \mathrm{CsClO}_4$, and NaF . Place these solutions in order of increasing pH .

Sima Sarker

Numerade Educator

Problem 154

The pH of human blood is steady at a value of approximately 7.4 owing to the following equilibrium reactions:
$$
\mathrm{CO}_2(a q)+\mathrm{H}_2 \mathrm{O}(l) \rightleftharpoons \mathrm{H}_2 \mathrm{CO}_3(a q) \rightleftharpoons \mathrm{HCO}_3{ }^{-}(a q)+\mathrm{H}^{+}(a q)
$$

Acids formed during normal cellular respiration react with the $\mathrm{HCO}_3{ }^{-}$to form carbonic acid, which is in equilibrium with $\mathrm{CO}_2(a q)$ and $\mathrm{H}_2 \mathrm{O}(l)$. During vigorous exercise, a person's $\mathrm{H}_2 \mathrm{CO}_3$ blood levels were 26.3 mM , whereas his $\mathrm{CO}_2$ levels were $1.63 \mathrm{~m} M$. On resting, the $\mathrm{H}_2 \mathrm{CO}_3$ levels declined to $24.9 \mathrm{~m} M$. What was the CO , blood level at rest?

James Irizarry

Numerade Educator

Problem 155

Hemoglobin (abbreviated Hb ) is a protein that is responsible for the transport of oxygen in the blood of mammals. Each hemoglobin molecule contains four iron atoms that are the binding sites for $\mathrm{O}_2$ molecules. The oxygen binding is pH dependent. The relevant equilibrium reaction is
$$
\mathrm{HbH}_4{ }^{4+}(a q)+4 \mathrm{O}_2(g) \rightleftharpoons \mathrm{Hb}\left(\mathrm{O}_2\right)_4(a q)+4 \mathrm{H}^{+}(a q)
$$

Use Le Châtelier's principle to answer the following.
a. What form of hemoglobin, $\mathrm{HbH}_4{ }^{4+}$ or $\mathrm{Hb}\left(\mathrm{O}_2\right)_4$, is favored in the lungs? What form is favored in the cells?
b. When a person hyperventilates, the concentration of $\mathrm{CO}_2$ in the blood is decreased. How does this affect the oxygenbinding equilibrium? How does breathing into a paper bag help to counteract this effect? (See Exercise 154.)
c. When a person has suffered a cardiac arrest, injection of a sodium bicarbonate solution is given. Why is this necessary?

Ronald Prasad

Numerade Educator

Problem 157

A $0.25-\mathrm{g}$ sample of lime $(\mathrm{CaO})$ is dissolved in enough water to make 1500 mL of solution. Calculate the pH of the solution.

James Irizarry

Numerade Educator

Problem 158

At $25^{\circ} \mathrm{C}$, a saturated solution of benzoic acid ( $\left.K_{\mathrm{a}}=6.4 \times 10^{-5}\right)$ has a pH of 2.80 . Calculate the water solubility of benzoic acid in moles per liter.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 159

Calculate the pH of an aqueous solution containing $1.0 \times 10^{-2} M \mathrm{HCl}, 1.0 \times 10^{-2} \mathrm{MH}_2 \mathrm{SO}_4$, and $1.0 \times 10^{-2} \mathrm{MHCN}$.

James Irizarry

Numerade Educator

Problem 160

Acrylic acid $\left(\mathrm{CH}_2=\mathrm{CHCO}_2 \mathrm{H}\right)$ is a precursor for many important plastics. $K_{\mathrm{a}}$ for acrylic acid is $5.6 \times 10^{-5}$.
a. Calculate the pH of a $0.10-\mathrm{M}$ solution of acrylic acid.
b. Calculate the percent dissociation of a $0.10-M$ solution of acrylic acid.
c. Calculate the pH of a $0.050-\mathrm{M}$ solution of sodium acrylate $\left(\mathrm{NaC}_3 \mathrm{H}_3 \mathrm{O}_2\right)$.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 161

Classify each of the following as a strong acid, weak acid, strong base, or weak base in aqueous solution.
a. $\mathrm{HNO}_2$
b. $\mathrm{HNO}_3$
c. $\mathrm{CH}_3 \mathrm{NH}_2$
g. $\mathrm{HC}-\mathrm{OH}$
d. NaOH
h. $\mathrm{Ca}(\mathrm{OH})_2$
e. $\mathrm{NH}_3$
i. $\mathrm{H}_2 \mathrm{SO}_4$
f. HF

Sima Sarker

Numerade Educator

Problem 162

The following illustration displays the relative number of species when an acid, HA, is added to water.

a. Is HA a weak or strong acid? How can you tell?
b. Using the relative numbers given in the illustration, determine the value for $K_{\mathrm{a}}$ and the percent dissociation of the acid. Assume the initial acid concentration is 0.20 M .

Ronald Prasad

Numerade Educator

Problem 163

Isocyanic acid (HNCO) can be prepared by heating sodium cyanate in the presence of solid oxalic acid according to the equation
$$
2 \mathrm{NaOCN}(s)+\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4(s) \longrightarrow 2 \mathrm{HNCO}(l)+\mathrm{Na}_2 \mathrm{C}_2 \mathrm{O}_4(s)
$$

Upon isolating pure $\mathrm{HNCO}(l)$, an aqueous solution of HNCO can be prepared by dissolving the liquid HNCO in water. What is the pH of a $100 .-\mathrm{mL}$ solution of HNCO prepared from the reaction of 10.0 g each of NaOCN and $\mathrm{H}_2 \mathrm{C}_2 \mathrm{O}_4$, assuming all of the HNCO produced is dissolved in solution? $\left(K_{\mathrm{a}}\right.$ of $\mathrm{HNCO}=$ $1.2 \times 10^{-4}$.)

James Irizarry

Numerade Educator

Problem 164

Quinine $\left(\mathrm{C}_{20} \mathrm{H}_{24} \mathrm{~N}_2 \mathrm{O}_2\right)$ is the most important alkaloid derived from cinchona bark. It is used as an antimalarial drug. For quinine, $\mathrm{p} K_{\mathrm{b}_1}=5.1$ and $\mathrm{p} K_{\mathrm{b}_2}=9.7\left(\mathrm{p} K_{\mathrm{b}}=-\log K_{\mathrm{b}}\right)$. Only 1 g quinine will dissolve in 1900.0 mL of solution. Calculate the pH of a saturated aqueous solution of quinine. Consider only the reaction $\mathrm{Q}+\mathrm{H}_2 \mathrm{O} \rightleftharpoons \mathrm{QH}^{+}+\mathrm{OH}^{-}$described by $\mathrm{p} K_{\mathrm{b},}$, where $\mathrm{Q}=$ quinine.

James Irizarry

Numerade Educator

Problem 165

Codeine $\left(\mathrm{C}_{18} \mathrm{H}_{21} \mathrm{NO}_3\right)$ is a derivative of morphine that is used as an analgesic, narcotic, or antitussive. It was once commonly used in cough syrups but is now available only by prescription because of its addictive properties. If the pH of a $1.7 \times 10^{-3}-M$ solution of codeine is 9.59 , calculate $K_{\mathrm{b}-}$

James Irizarry

Numerade Educator

Problem 167

Rank the following 0.10 M solutions in order of increasing pH .
a. $\mathrm{HI}, \mathrm{HF}, \mathrm{NaF}, \mathrm{NaI}$
b. $\mathrm{NH}_4 \mathrm{Br}, \mathrm{HBr}, \mathrm{KBr}, \mathrm{NH}_3$
c. $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3 \mathrm{NO}_3, \mathrm{NaNO}_3, \mathrm{NaOH}, \mathrm{HOC}_6 \mathrm{H}_5, \mathrm{KOC}_6 \mathrm{H}_5$, $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2, \mathrm{HNO}_3$

Ronald Prasad

Numerade Educator

Problem 168

Is an aqueous solution of $\mathrm{NaHSO}_4$ acidic, basic, or neutral? What reaction occurs with water? Calculate the pH of a $0.10-\mathrm{M}$ solution of $\mathrm{NaHSO}_4$.

Anand Jangid

Numerade Educator

Problem 169

Calculate the value for the equilibrium constant for each of the following aqueous reactions.
a. $\mathrm{NH}_3+\mathrm{H}_3 \mathrm{O}^{+} \rightleftharpoons \mathrm{NH}_4^{+}+\mathrm{H}_2 \mathrm{O}$
b. $\mathrm{NO}_2^{-}+\mathrm{H}_3 \mathrm{O}^{+} \rightleftharpoons \mathrm{HNO}_2+\mathrm{H}_2 \mathrm{O}$
c. $\mathrm{NH}_4^{+}+\mathrm{OH}^{-} \rightleftharpoons \mathrm{NH}_3+\mathrm{H}_2 \mathrm{O}$
d. $\mathrm{HNO}_2+\mathrm{OH}^{-} \rightleftharpoons \mathrm{H}_2 \mathrm{O}+\mathrm{NO}_2^{-}$

James Irizarry

Numerade Educator

Problem 170

Students are often surprised to learn that organic acids, such as acetic acid, contain - OH groups. Actually, all oxyacids contain hydroxy1 groups. Sulfuric acid, usually written as $\mathrm{H}_2 \mathrm{SO}_4$, has the structural formula $\mathrm{SO}_2(\mathrm{OH})_2$, where S is the central atom. Identify the acids whose structural formulas are shown below. Why do they behave as acids, while NaOH and KOH are bases?
a. $\mathrm{SO}(\mathrm{OH})_2$
b. $\mathrm{ClO}_2(\mathrm{OH})$
c. $\mathrm{HPO}(\mathrm{OH})_2$

Ian Kaigh

Numerade Educator

Problem 171

A certain acid, HA, has a vapor density of $5.11 \mathrm{~g} / \mathrm{L}$ when in the gas phase at a temperature of $25^{\circ} \mathrm{C}$ and a pressure of 1.00 atm . When 1.50 g of this acid is dissolved in enough water to make 100.0 mL of solution, the pH is found to be 1.80. Calculate $K_{\mathrm{a}}$ for the acid.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 172

The pH of $1.0 \times 10^{-8} \mathrm{M}$ hydrochloric acid is not 8.00 . The correct pH can be calculated by considering the relationship between the molarities of the three principal ions in the solution $\left(\mathrm{H}^{+}, \mathrm{Cl}^{-}\right.$, and $\left.\mathrm{OH}^{-}\right)$. These molarities can be calculated from algebraic equations that can be derived from the considerations given below.
a. The solution is electrically neutral.
b. The hydrochloric acid can be assumed to be $100 \%$ ionized.
c. The product of the molarities of the hydronium ions and the hydroxide ions must equal $K_{\mathrm{w}}$.
Calculate the pH of a $1.0 \times 10^{-8}-M \mathrm{HCl}$ solution.

James Irizarry

Numerade Educator

Problem 173

Calculate the pH of a $1.0 \times 10^{-7}-M$ solution of NaOH in water.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 174

Calculate $\left[\mathrm{OH}^{-}\right]$in a $3.0 \times 10^{-7}-M$ solution of $\mathrm{Ca}(\mathrm{OH})_2$.

James Irizarry

Numerade Educator

Problem 175

Consider 50.0 mL of a solution of weak acid HA ( $K_{\mathrm{a}}=$ $1.00 \times 10^{-6}$ ), which has a pH of 4.000 . What volume of water must be added to make the $\mathrm{pH}=5.000$ ?

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 176

Making use of the assumptions we ordinarily make in calculating the pH of an aqueous solution of a weak acid, calculate the pH of a $1.0 \times 10^{-6}-\mathrm{M}$ solution of hypobromous acid $(\mathrm{HBrO}$, $K_{\mathrm{a}}=2 \times 10^{-9}$ ). What is wrong with your answer? Why is it wrong? Without trying to solve the problem, explain what has to be included to solve the problem correctly.

James Irizarry

Numerade Educator

Problem 178

Determine the pH of $\mathrm{a} .50-\mathrm{M}$ solution of $\mathrm{NH}_4 \mathrm{OCl}$. (See Exercise 177.)

Shalini Tyagi

Numerade Educator

Problem 179

Calculate $\left[\mathrm{OH}^{-}\right]$in a solution obtained by adding 0.0100 mol solid NaOH to 1.00 L of $15.0 \mathrm{MHH}_3$.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 180

What mass of $\mathrm{NaOH}(\mathrm{s})$ must be added to 1.0 L of 0.050 M $\mathrm{NH}_3$ to ensure that the percent ionization of $\mathrm{NH}_3$ is no greater than $0.0010 \%$ ? Assume no volume change on addition of NaOH .

James Irizarry

Numerade Educator

Problem 181

Consider 1000 mL of a $1.00 \times 10^{-4}-M$ solution of a certain acid HA that has a $K_{\mathrm{a}}$ value equal to $1.00 \times 10^{-4}$. How much water was added or removed (by evaporation) so that a solution remains in which $25.0 \%$ of HA is dissociated at equilibrium? Assume that HA is nonvolatile.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 182

Calculate the mass of sodium hydroxide that must be added to 1.00 L of $1.00-M \mathrm{HC}_2 \mathrm{H}_3 \mathrm{O}_2$ to double the pH of the solution (assume that the added NaOH does not change the volume of the solution).

James Irizarry

Numerade Educator

Problem 183

Consider the species $\mathrm{PO}_4{ }^{3-}, \mathrm{HPO}_4{ }^{2-}$, and $\mathrm{H}_2 \mathrm{PO}_4{ }^{-}$. Each ion can act as a base in water. Determine the $K_{\mathrm{b}}$ value for each of these species. Which species is the strongest base?

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 184

Calculate the pH of a $0.10-M$ solution of sodium phosphate. (See Exercise 183.)

James Irizarry

Numerade Educator

Problem 185

Will 0.10 M solutions of the following salts be acidic, basic, or neutral? See Appendix 5 for $K_{\mathrm{a}}$ values.
a. ammonium bicarbonate
b. sodium dihydrogen phosphate
c. sodium hydrogen phosphate
d. ammonium dihydrogen phosphate
e. ammonium formate

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 186

a. The principal equilibrium in a solution of $\mathrm{NaHCO}_3$ is
$$
\mathrm{HCO}_3{ }^{-}(a q)+\mathrm{HCO}_3{ }^{-}(a q) \rightleftharpoons \mathrm{H}_2 \mathrm{CO}_3(a q)+\mathrm{CO}_3{ }^{2-}(a q)
$$

Calculate the value of the equilibrium constant for this reaction.
b. At equilibrium, what is the relationship between $\left[\mathrm{H}_2 \mathrm{CO}_3\right]$ and $\left[\mathrm{CO}_3{ }^{2-}\right]$ ?
c. Using the equilibrium
$$
\mathrm{H}_2 \mathrm{CO}_3(a q) \rightleftharpoons 2 \mathrm{H}^{+}(a q)+\mathrm{CO}_3{ }^{2-}(a q)
$$
derive an expression for the pH of the solution in terms of $K_{\mathrm{a}_4}$ and $K_{\mathrm{a}_4}$ using the result from part b.
d. What is the pH of a solution of $\mathrm{NaHCO}_3$ ?

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 187

A $0.100-\mathrm{g}$ sample of the weak acid HA (molar mass $=$ $100.0 \mathrm{~g} / \mathrm{mol}$ ) is dissolved in 500.0 g water. The freezing point of the resulting solution is $-0.0056^{\circ} \mathrm{C}$. Calculate the value of $K_a$ for this acid. Assume molality equals molarity in this solution.

Anatole Borisov

Anatole Borisov

Numerade Educator

Problem 188

A sample containing 0.0500 mole of $\mathrm{Fe}_2\left(\mathrm{SO}_4\right)_3$ is dissolved in enough water to make 1.00 L of solution. This solution contains hydrated $\mathrm{SO}_4{ }^{2-}$ and $\mathrm{Fe}^{3+}$ ions. The latter behaves as an acid:
$$
\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6{ }^{3+}(a q) \rightleftharpoons \mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_5 \mathrm{OH}^{2+}(a q)+\mathrm{H}^{+}(a q)
$$
a. Calculate the expected osmotic pressure of this solution at $25^{\circ} \mathrm{C}$ if the above dissociation is negligible.
b. The actual osmotic pressure of the solution is 6.73 atm at $25^{\circ} \mathrm{C}$. Calculate $K_\alpha$ for the dissociation reaction of $\mathrm{Fe}\left(\mathrm{H}_2 \mathrm{O}\right)_6{ }^{3+}$. (To do this calculation, you must assume that none of the ions go through the semipermeable membrane. Actually, this is not a great assumption for the tiny $\mathrm{H}^{+}$ion.)

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 190

For the following, mix equal volumes of one solution from Group I with one solution from Group II to achieve the indicated pH . Calculate the pH of each solution.
Group I: $\quad 0.20 \mathrm{MNH} \mathrm{Nl}_4, 0.20 \mathrm{MHCl}, 0.20 \mathrm{MC}_6 \mathrm{H}_5 \mathrm{NH}_3 \mathrm{Cl}$, $0.20 \mathrm{M}\left(\mathrm{C}_2 \mathrm{H}_5\right)_3 \mathrm{NHCl}$
Group II: $\quad 0.20 \mathrm{MOI}, 0.20 \mathrm{MNaCN}, 0.20 \mathrm{MKOCl}, 0.20$ $M \mathrm{NaNO}_2$
a. the solution with the lowest pH
b. the solution with the highest pH
c. the solution with the pH closest to 7.00

Susan Hallstrom

Susan Hallstrom

Numerade Educator

Problem 1541

Calculate the pH of the following solutions:
a. $1.2 \mathrm{M} \mathrm{CaBr}_2$
b. $0.84 M \mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_3 \mathrm{NO}_3\left(K_{\mathrm{b}}\right.$ for $\mathrm{C}_6 \mathrm{H}_5 \mathrm{NH}_2=3.8 \times 10^{-10}$ )
c. $0.57 \mathrm{MKC}_7 \mathrm{H}_5 \mathrm{O}_2\left(K_2\right.$ for $\left.\mathrm{HC}_7 \mathrm{H}_5 \mathrm{O}_2=6.4 \times 10^{-5}\right)$

Ronald Prasad

Numerade Educator