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Chemistry

Steven S. Zumdahl, Susan A. Zumdahls

Chapter 14

Acids and Bases - all with Video Answers

Educators

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Chapter Questions

05:07

Problem 1

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

MB
Marisa Bellino
Numerade Educator
08:39

Problem 2

Differentiate between the terms strength 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 base of a weak acid a strong base?

Eric Ferrara
Eric Ferrara
Numerade Educator
01:04

Problem 3

Sketch two graphs: (a) percent dissociation for weak acid HA versus the initial concentration of $\mathrm{HA}\left([\mathrm{HA}]_{0}\right)$ and (b) $\mathrm{H}^{+}$ concentration versus [HA] $_{0}$. Explain both.

David Collins
David Collins
Numerade Educator
02:23

Problem 4

Consider a solution prepared by mixing a weak acid HA and $\mathrm{HCl}$. What are the major species? Explain what is occurring in solution. How would you calculate the $\mathrm{pH}$ ? What if you added NaA to this solution? Then added $\mathrm{NaOH}$ ?

Eric Ferrara
Eric Ferrara
Numerade Educator
03:21

Problem 5

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

Anatole Borisov
Anatole Borisov
Numerade Educator
05:49

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 looks like at equilibrium.
b. What are the major species in each beaker?
c. From your pictures, calculate the $K_{a}$ values of each acid.
d. Order the following from the strongest to the weakest base:
$\mathrm{H}_{2} \mathrm{O}, \mathrm{A}^{-}, \mathrm{Cl}^{-} .$ Explain your order.

Eric Ferrara
Eric Ferrara
Numerade Educator
01:13

Problem 7

You are asked to calculate the $\mathrm{H}^{+}$ concentration in a solution of $\mathrm{NaOH}(a q) .$ Because sodium hydroxide is a base, can we say there is no $\mathrm{H}^{+}$, since having $\mathrm{H}^{+}$ would imply that the solution is acidic?

Anatole Borisov
Anatole Borisov
Numerade Educator
04:46

Problem 8

Consider a solution prepared by mixing a weak acid HA, HCl. and NaA. Which of the following statements best describes what happens?
a. The $\mathrm{H}^{+}$ from the $\mathrm{HCl}$ reacts completely with the $\mathrm{A}^{-}$ from the $\mathrm{NaA}$. Then the HA dissociates somewhat.
b. The $\mathrm{H}^{+}$ from the $\mathrm{HCl}$ reacts somewhat with the $\mathrm{A}^{-}$ from the NaA to make HA, while the HA is dissociating. Eventually you have equal amounts of everything.
c. The $\mathrm{H}^{+}$ from the $\mathrm{HCl}$ reacts 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 $\mathrm{HCl}$ reacts completely with the $\mathrm{A}^{-}$ from the $\mathrm{NaA}$. Then the HA dissociates somewhat until "too much" $\mathrm{H}^{+}$ and $\mathrm{A}^{-}$ are formed, so the $\mathrm{H}^{+}$ and $\mathrm{A}^{-}$ react to form $\mathrm{HA}$, 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
Ronald Prasad
Numerade Educator
View

Problem 9

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

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:37

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
Ronald Prasad
Numerade Educator
04:22

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 $K_{a}=1 / K_{\mathrm{b}}$. 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
02:38

Problem 12

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

Eric Ferrara
Eric Ferrara
Numerade Educator
01:18

Problem 13

What is meant by $p H ?$ True or false: A strong acid solution always has a lower $\mathrm{pH}$ than a weak acid solution. Explain.

Anand Jangid
Anand Jangid
Numerade Educator
02:42

Problem 14

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

Eric Ferrara
Eric Ferrara
Numerade Educator
01:26

Problem 15

Can the $\mathrm{pH}$ of a solution be negative? Explain.

Anatole Borisov
Anatole Borisov
Numerade Educator
03:23

Problem 16

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?

Ronald Prasad
Ronald Prasad
Numerade Educator
01:20

Problem 17

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

Cheryl Glor
Cheryl Glor
Numerade Educator
02:31

Problem 18

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
Eric Ferrara
Numerade Educator
08:07

Problem 19

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
Ian Kaigh
Numerade Educator
02:15

Problem 20

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

Ronald Prasad
Ronald Prasad
Numerade Educator
05:05

Problem 21

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.

Ian Kaigh
Ian Kaigh
Numerade Educator
05:00

Problem 22

Which of the following statements is(are) true? Correct the false statements.
a. When a base is dissolved in water, the lowest possible $\mathrm{pH}$ of the solution is $7.0$.
b. When an acid is dissolved in water, the lowest possible $\mathrm{pH}$ is $0 .$
c. A strong acid solution will have a lower $\mathrm{pH}$ than a weak acid solution.
d. A $0.0010 \mathrm{M} \mathrm{Ba}(\mathrm{OH})_{2}$ solution has a pOH that is twice the $\mathrm{pOH}$ value of a $0.0010 \mathrm{M} \mathrm{KOH}$ solution.

Cheryl Glor
Cheryl Glor
Numerade Educator
View

Problem 23

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. $\left[\mathrm{OH}^{-}\right]=2[\mathbf{B}]_{\text {? }}$
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 $\left[\mathrm{OH}^{-}\right] \cdot\left[\mathrm{Ha}_{0}\right]$ and $[\mathrm{B}]$ represent initial concentrations of an acid or a base.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:08

Problem 24

Consider a $0.10 \mathrm{M} \mathrm{H}_{2} \mathrm{CO}_{3}$ solution and a $0.10 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$ 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 $0.10 \mathrm{M}$
b. The $\left[\mathrm{H}^{+}\right]$ is $0.10 \mathrm{M}$.
c. The $\left[\mathrm{H}^{+}\right]$ is between $0.10 M$ and $0.20 \mathrm{M}$.
d. The $\left[\mathrm{H}^{+}\right]$ is $0.20 \mathrm{M}$.

Tracy Tourville
Tracy Tourville
Numerade Educator
02:40

Problem 25

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

Ian Kaigh
Ian Kaigh
Numerade Educator
01:04

Problem 26

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
Eric Ferrara
Numerade Educator
02:44

Problem 27

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
Ian Kaigh
Numerade Educator
02:18

Problem 28

Write the dissociation reaction and the corresponding $K_{a}$ equilibrium expression for each of the following acids in water.
a. HCN
b. $\mathrm{HOC}_{6} \mathrm{H}_{5}$
c. $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{3}^{+}$

Eric Ferrara
Eric Ferrara
Numerade Educator
01:49

Problem 29

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. $\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{NH}^{+}+\mathrm{H}_{2} \mathrm{O} \rightleftharpoons \mathrm{C}_{3} \mathrm{H}_{5} \mathrm{~N}+\mathrm{H}_{3} \mathrm{O}^{+}$
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
02:43

Problem 30

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
Eric Ferrara
Numerade Educator
01:38

Problem 31

Classify each of the following as a strong acid or a weak acid.

Ian Kaigh
Ian Kaigh
Numerade Educator
01:44

Problem 32

Consider the following illustrations:

David Collins
David Collins
Numerade Educator
01:30

Problem 33

Use Table $14.2$ to order the following from the strongest to the weakest acid.
$$
\mathrm{HClO}_{2}, \mathrm{H}_{2} \mathrm{O}, \mathrm{NH}_{4}^{+}, \mathrm{HClO}_{4}
$$

Ian Kaigh
Ian Kaigh
Numerade Educator
02:49

Problem 34

Use Table $14.2$ to order the following from the strongest to the weakest base.
$$
\mathrm{ClO}_{2}^{-}, \mathrm{H}_{2} \mathrm{O}, \mathrm{NH}_{3}, \mathrm{ClO}_{4}^{-}
$$

Eric Ferrara
Eric Ferrara
Numerade Educator
02:02

Problem 35

You may need Table $14.2$ to answer the following questions.
a. Which is the stronger acid, $\mathrm{HCl}$ 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, $\mathrm{HCN}$ or $\mathrm{HOC}_{6} \mathrm{H}_{5}$ ?

Ian Kaigh
Ian Kaigh
Numerade Educator
00:20

Problem 36

You may need Table $14.2$ 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 $\mathrm{OC}_{6} \mathrm{H}_{5}^{-}$ ?

Eric Ferrara
Eric Ferrara
Numerade Educator
02:36

Problem 37

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. $\left[\mathrm{H}^{+}\right]=1.0 \times 10^{-7} M$
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
Ronald Prasad
Numerade Educator
03:13

Problem 38

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. $\left[\mathrm{OH}^{-}\right]=1.5 \mathrm{M}$
c. $\left[\mathrm{OH}^{-}\right]=1.0 \times 10^{-7} M$
b. $\left[\mathrm{OH}^{-}\right]=3.6 \times 10^{-15} \mathrm{M}$
d. $\left[\mathrm{OH}^{-}\right]=7.3 \times 10^{-4} \mathrm{M}$

Nicole Krahulik
Nicole Krahulik
Numerade Educator
02:36

Problem 39

Values of $K_{\mathrm{w}}$ as a function of temperature are as follows:
\begin{tabular}{cc}
Temperature $\left({ }^{\circ} \mathrm{C}\right)$ & $\boldsymbol{K}_{\mathrm{w}}$ \\
\hline 0 & $1.14 \times 10^{-15}$ \\
25 & $1.00 \times 10^{-14}$ \\
35 & $2.09 \times 10^{-14}$ \\
$40 .$ & $2.92 \times 10^{-14}$ \\
$50 .$ & $5.47 \times 10^{-14}$
\end{tabular}
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
Sima Sarker
Numerade Educator
02:43

Problem 40

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 $\mathrm{pH}$ of pure water at $40^{\circ} \mathrm{C} ?$
c. If the hydroxide ion concentration in a solution is $0.10 M$, what is the $\mathrm{pH}$ at $40^{\circ} \mathrm{C}$ ?

Eric Ferrara
Eric Ferrara
Numerade Educator
04:47

Problem 41

Calculate the $\mathrm{pH}$ and $\mathrm{pOH}$ of the solutions in Exercises 37 and $3 \overline{8}$.

David Collins
David Collins
Numerade Educator
08:08

Problem 42

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 $\mathrm{pH}$ 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
Ian Kaigh
Numerade Educator
05:18

Problem 43

Fill in the missing information in the following table.

Eric Ferrara
Eric Ferrara
Numerade Educator
05:18

Problem 44

Fill in the missing information in the following table.

Eric Ferrara
Eric Ferrara
Numerade Educator
01:03

Problem 45

The $\mathrm{pH}$ 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
Ronald Prasad
Numerade Educator
01:00

Problem 46

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?

Ronald Prasad
Ronald Prasad
Numerade Educator
01:10

Problem 47

What are the major species present in $0.250 \mathrm{M}$ solutions of each of the following acids? Calculate the $\mathrm{pH}$ of each of these solutions.
a. $\mathrm{HClO}_{4}$
b. $\mathrm{HNO}_{3}$

Ronald Prasad
Ronald Prasad
Numerade Educator
02:59

Problem 48

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

Sima Sarker
Sima Sarker
Numerade Educator
09:11

Problem 49

A solution is prepared by adding $50.0 \mathrm{~mL}$ of $0.050 \mathrm{M} \mathrm{HCl}$ to $150.0 \mathrm{~mL}$ of $0.10 \mathrm{M} \mathrm{HNO}_{3} .$ Calculate the concentrations of all species in this solution.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
05:30

Problem 50

A solution is prepared by mixing $90.0 \mathrm{~mL}$ of $5.00 \mathrm{M} \mathrm{HCl}$ and $30.0 \mathrm{~mL}$ of $8.00 \mathrm{M} \mathrm{HNO}_{3}$. Water is then added until the final volume is $1.00$ L. Calculate $\left[\mathrm{H}^{+}\right],\left[\mathrm{OH}^{-}\right]$, and the $\mathrm{pH}$ for this solution.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
02:04

Problem 51

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

Nicole Krahulik
Nicole Krahulik
Numerade Educator
02:27

Problem 52

What mass of $\mathrm{HNO}_{3}$ is present in $250.0 \mathrm{~mL}$ of a nitric acid solution having a $\mathrm{pH}=5.10 ?$

Nicole Krahulik
Nicole Krahulik
Numerade Educator
04:53

Problem 53

What are the major species present in $0.250 \mathrm{M}$ solutions of each of the following acids? Calculate the $\mathrm{pH}$ of each of these solutions.
a. HNO $_{2}$
b. $\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}\left(\mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}\right)$

Ronald Prasad
Ronald Prasad
Numerade Educator
04:33

Problem 54

What are the major species present in $0.250 M$ solutions of each of the following acids? Calculate the $\mathrm{pH}$ of each of these solutions.
a. $\mathrm{HOC}_{6} \mathrm{H}_{5}$
b. HCN

Ronald Prasad
Ronald Prasad
Numerade Educator
07:40

Problem 55

A $0.0560-\mathrm{g}$ sample of acetic acid is added to enough water to make $50.00 \mathrm{~mL}$ of solution. Calculate $\left[\mathrm{H}^{+}\right],\left[\mathrm{CH}_{3} \mathrm{COO}^{-}\right]$, $\left[\mathrm{CH}_{3} \mathrm{COOH}\right]$, and the $\mathrm{pH}$ at equilibrium. $K_{\mathrm{a}}$ for acetic acid is $1.8 \times 10^{-5}$

Shalini Tyagi
Shalini Tyagi
Numerade Educator
07:16

Problem 56

For propanoic acid $\left(\mathrm{HC}_{3} \mathrm{H}_{5} \mathrm{O}_{2}, K_{2}=1.3 \times 10^{-5}\right)$, determine the
concentration of all species present, the $\mathrm{pH}$, and the percent dissociation of a $0.100 M$ solution.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
05:41

Problem 57

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

Anatole Borisov
Anatole Borisov
Numerade Educator
03:11

Problem 58

Calculate the $\mathrm{pH}$ of a $0.20 \mathrm{M}$ solution of iodic acid $\left(\mathrm{HIO}_{3}, K_{\alpha}=0.17\right) .$

Shalini Tyagi
Shalini Tyagi
Numerade Educator
05:16

Problem 59

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 $K_{a}$ for monochloroacetic acid is $1.35 \times 10^{-3}$. Calculate the $\mathrm{pH}$ of a $0.10 \mathrm{M}$ solution of monochloroacetic acid.

James Irizarry
James Irizarry
Numerade Educator
06:48

Problem 60

A typical aspirin tablet contains $325 \mathrm{mg}$ of acetylsalicylic acid. $\mathrm{HC}_{9} \mathrm{H}_{7} \mathrm{O}_{4} .$ Calculate the $\mathrm{pH}$ of a solution that is prepared by dissolving two aspirin tablets in one cup ( $237 \mathrm{~mL}$ ) of solution. Assume the aspirin tablets are pure acetylsalicylic acid, $K_{a}=3.3 \times 10^{-4}$

Shalini Tyagi
Shalini Tyagi
Numerade Educator
04:52

Problem 61

Calculate the $\mathrm{pH}$ of each of the following.
a. a solution containing $0.10 \mathrm{M} \mathrm{HCl}$ and $0.10 \mathrm{M} \mathrm{HOCl}$
b. a solution containing $0.050 \mathrm{M} \mathrm{HNO}_{3}$ and $0.50 \mathrm{M} \mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}$.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
01:23

Problem 62

Calculate the $\mathrm{pH}$ of a solution that contains $1.0 \mathrm{M} \mathrm{HF}$ 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.

David Collins
David Collins
Numerade Educator
08:06

Problem 63

Calculate the percent dissociation of the acid in each of the following solutions.
a. $0.50 M$ acetic acid
b. $0.050 \mathrm{M}$ acetic acid
c. $0.0050 \mathrm{M}$ 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 $\mathrm{c}$, the $\left[\mathrm{H}^{+}\right]$ decreases. Explain.

Anatole Borisov
Anatole Borisov
Numerade Educator
02:03

Problem 64

Using the $K_{a}$ values in Table $14.2$, 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
David Collins
Numerade Educator
04:12

Problem 65

A $0.15 M$ solution of a weak acid is $3.0 \%$ dissociated. Calculate $K_{n}$.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
02:59

Problem 66

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

James Irizarry
James Irizarry
Numerade Educator
03:53

Problem 67

The $\mathrm{pH}$ of a $1.00 \times 10^{-2} \mathrm{M}$ solution of cyanic acid (HOCN) is $2.77$ at $25^{\circ} \mathrm{C}$. Calculate $K_{a}$ for HOCN from this result.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
04:00

Problem 68

Trichloroacetic acid $\left(\mathrm{CCl}_{3} \mathrm{CO}_{2} \mathrm{H}\right)$ is a corrosive acid that is used to precipitate proteins. The $\mathrm{pH}$ of a $0.050 \mathrm{M}$ solution of trichloroacetic acid is the same as the $\mathrm{pH}$ of a $0.040 \mathrm{M} \mathrm{HClO}_{4}$ solution. Calculate $K_{a}$ for trichloroacetic acid.

Sima Sarker
Sima Sarker
Numerade Educator
04:30

Problem 69

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
03:20

Problem 70

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

Anatole Borisov
Anatole Borisov
Numerade Educator
02:33

Problem 71

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
02:53

Problem 72

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
James Irizarry
Numerade Educator
01:44

Problem 73

Use Table $14.3$ to help order the following bases from strongest to weakest.
$$
\begin{array}{llll}
\mathrm{NO}_{3}^{-}, & \mathrm{H}_{2} \mathrm{O}, & \mathrm{NH}_{3}, & \mathrm{C}_{5} \mathrm{H}_{5} \mathrm{~N}
\end{array}
$$

Sima Sarker
Sima Sarker
Numerade Educator
04:59

Problem 74

Use Table $14.3$ to help order the following acids from strongest to weakest.
$$
\mathrm{HNO}_{3}, \quad \mathrm{H}_{2} \mathrm{O}, \quad \mathrm{NH}_{4}^{+}, \quad \mathrm{C}_{5} \mathrm{H}_{5} \mathrm{NH}^{+}
$$

Sima Sarker
Sima Sarker
Numerade Educator
02:28

Problem 75

Use Table $14.3$ 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 $\mathrm{CH}_{3} \mathrm{NH}_{2} ?$

Sima Sarker
Sima Sarker
Numerade Educator
05:31

Problem 76

Use Table $14.3$ 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 $\mathrm{CH}_{3} \mathrm{NH}_{3}{ }^{+}$ ?

Sima Sarker
Sima Sarker
Numerade Educator
01:39

Problem 77

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

Nicole Krahulik
Nicole Krahulik
Numerade Educator
04:56

Problem 78

Calculate [OH $^{-}$ ], pOH, and pH for each of the following.
a. $0.00040 \mathrm{M} \mathrm{Ca}(\mathrm{OH})_{2}$
b. a solution containing $25 \mathrm{~g}$ of $\mathrm{KOH}$ per liter
c. a solution containing $150.0 \mathrm{~g}$ of $\mathrm{NaOH}$ per liter

Cheryl Glor
Cheryl Glor
Numerade Educator
03:06

Problem 79

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 [OH $]$ and the $\mathrm{pH}$ of each of these solutions?

Cheryl Glor
Cheryl Glor
Numerade Educator
02:18

Problem 80

What are the major species present in the following mixtures of bases?
a. $0.050 \mathrm{M} \mathrm{NaOH}$ and $0.050 \mathrm{M} \mathrm{LiOH}$
b. $0.0010 \mathrm{M} \mathrm{Ca}(\mathrm{OH})_{2}$ and $0.020 \mathrm{M} \mathrm{RbOH}$
What is $\left[\mathrm{OH}^{-}\right]$ and the $\mathrm{pH}$ of each of these solutions?

David Collins
David Collins
Numerade Educator
02:37

Problem 81

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

Anatole Borisov
Anatole Borisov
Numerade Educator
03:55

Problem 82

Calculate the concentration of an aqueous $\mathrm{Sr}(\mathrm{OH})_{2}$ that has $\mathrm{pH}=10.50$

James Irizarry
James Irizarry
Numerade Educator
04:02

Problem 83

What are the major species present in a $0.150 \mathrm{M} \mathrm{NH}_{3}$ solution? Calculate the $\left[\mathrm{OH}^{-}\right]$ and the $\mathrm{pH}$ of this solution.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
04:10

Problem 84

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 $\mathrm{pH}$ of a $2.0 \mathrm{M}$ solution of hydrazine in water.

James Irizarry
James Irizarry
Numerade Educator
05:40

Problem 85

Calculate $\left[\mathrm{OH}^{-}\right],\left[\mathrm{H}^{+}\right]$, and the $\mathrm{pH}$ of $0.20 \mathrm{M}$ 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
Ronald Prasad
Numerade Educator
09:40

Problem 86

Calculate $\left[\mathrm{OH}^{-}\right],\left[\mathrm{H}^{+}\right]$, and the $\mathrm{pH}$ of $0.20 \mathrm{M}$ solutions of each of the following amines (the $K_{\triangleright}$ values are found in Table $14.3$.
a. aniline
b. methylamine

Shalini Tyagi
Shalini Tyagi
Numerade Educator
View

Problem 87

Calculate the $\mathrm{pH}$ of a $0.20 \mathrm{M} \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NH}_{2}$ solution $\left(K_{\mathrm{b}}=\right.$
$5.6 \times 10^{-4}$ ).

Tanvi Garg
Tanvi Garg
Numerade Educator
06:01

Problem 88

Calculate the $\mathrm{pH}$ of a $0.050 \mathrm{M}\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{2} \mathrm{NH}$ solution $\left(K_{\mathrm{b}}=1.3 \times\right.$
$\left.10^{-3}\right)$

James Irizarry
James Irizarry
Numerade Educator
06:59

Problem 89

Calculate the percent ionization in each of the following solutions.
a. $0.10 \mathrm{M} \mathrm{NH}_{3}$
b. $0.010 \mathrm{M} \mathrm{NH}_{3}$

Shalini Tyagi
Shalini Tyagi
Numerade Educator
02:48

Problem 90

Calculate the percentage of pyridine $\left(\mathrm{C}_{3} \mathrm{H}_{5} \mathrm{~N}\right)$ that forms pyridinium ion, $\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{NH}^{+}$, in a $0.10 \mathrm{M}$ aqueous solution of pyridine $\left(K_{\mathrm{b}}=1.7 \times 10^{-9}\right)$

Shalini Tyagi
Shalini Tyagi
Numerade Educator
04:54

Problem 91

Codeine $\left(\mathrm{C}_{18} \mathrm{H}_{21} \mathrm{NO}_{3}\right)$ is a derivative of morphine that is used as ân 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 $\mathrm{pH}$ of a $1.7 \times 10^{-3} \mathrm{M}$ solution of codeine is $9.59$, calculate $K_{\mathrm{b}}$.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
04:33

Problem 92

Calculate the mass of $\mathrm{HONH}_{2}$ required to dissolve in enough water to make $250.0 \mathrm{~mL}$ of solution having a $\mathrm{pH}$ of $10.00$. $\left(K_{\mathrm{b}}=1.1 \times 10^{-8}\right)$

Anatole Borisov
Anatole Borisov
Numerade Educator
01:11

Problem 93

Write out the stepwise $K_{\mathrm{a}}$ reactions for the diprotic acid $\mathrm{H}_{2} \mathrm{SO}_{3}$

Anatole Borisov
Anatole Borisov
Numerade Educator
01:51

Problem 94

Write out the stepwise $K_{a}$ reactions for citric acid $\left(\mathrm{H}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{O}_{7}\right)$, a triprotic acid.

James Irizarry
James Irizarry
Numerade Educator
09:39

Problem 95

Using the $K_{\mathrm{a}}$ values in Table $14.4$ and only the first dissociation step, calculate the $\mathrm{pH}$ of $0.10 \mathrm{M}$ solutions of each of the following polyprotic acids.
a. $\mathrm{H}_{3} \mathrm{PO}_{4}$
b. $\mathrm{H}_{2} \mathrm{CO}_{3}$

Shalini Tyagi
Shalini Tyagi
Numerade Educator
View

Problem 96

Arsenic acid $\left(\mathrm{H}_{3} \mathrm{AsO}_{4}\right)$ is a triprotic acid with $K_{\mathrm{a}_{1}}=5 \times 10^{-3}$, $K_{L_{3}}=8 \times 10^{-8}$, and $K_{u_{k}}=6 \times 10^{-10}$. Calculate $\left[\mathrm{H}^{+}\right],\left[\mathrm{OH}^{-}\right]$,
$\left[\mathrm{H}_{3} \mathrm{AsO}_{4}\right],\left[\mathrm{H}_{2} \mathrm{As} \mathrm{O}_{4}^{-}\right],\left[\mathrm{HAsO}_{4}{ }^{2-}\right]$, and $\left[\mathrm{AsO}_{4}{ }^{3-}\right]$ in a $0.20 \mathrm{M}$
arsenic acid solution.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:40

Problem 97

Calculate the $\mathrm{pH}$ of a $2.0 \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$ solution.

Nicole Krahulik
Nicole Krahulik
Numerade Educator
01:34

Problem 98

Calculate the $\mathrm{pH}$ of a $5.0 \times 10^{-3} \mathrm{M}$ solution of $\mathrm{H}_{2} \mathrm{SO}_{4}$.

James Irizarry
James Irizarry
Numerade Educator
06:49

Problem 99

Arrange the following $0.10 M$ solutions in order of most acidic to most basic.
$\begin{array}{llll}\mathrm{KOH}, & \mathrm{KCl}, & \mathrm{KCN}, & \mathrm{NH}_{4} \mathrm{Cl}, & \mathrm{HCl}\end{array}$

Cheryl Glor
Cheryl Glor
Numerade Educator
03:50

Problem 100

Arrange the following $0.10 \mathrm{M}$ solutions in order from most acidic to most basic. See Appendix 5 for $K_{u}$ and $K_{\mathrm{b}}$ values.
$\mathrm{CaBr}_{2}, \mathrm{KNO}_{2}, \mathrm{HClO}_{4}, \mathrm{HNO}_{2}, \mathrm{HONH}_{3} \mathrm{ClO}_{4}$

David Collins
David Collins
Numerade Educator
00:55

Problem 101

Given that the $K_{a}$ value for acetic acid is $1.8 \times 10^{-5}$ and the $K_{a}$ 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
03:21

Problem 102

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
James Irizarry
Numerade Educator
05:44

Problem 103

Sodium azide $\left(\mathrm{NaN}_{3}\right)$ is sometimes added to water to kill bacteria. Calculate the concentration of all species in a $0.010 \mathrm{M}$ 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
Sima Sarker
Numerade Educator
04:11

Problem 104

Calculate the concentrations of all species present in a $0.25 \mathrm{M}$ solution of ethylammonium chloride $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NH}_{3} \mathrm{Cl}\right)$.

James Irizarry
James Irizarry
Numerade Educator
02:43

Problem 105

Calculate the $\mathrm{pH}$ of each of the following solutions.
a. $0.10 \mathrm{M} \mathrm{CH}_{3} \mathrm{NH}_{3} \mathrm{Cl}$
b. $0.050 \mathrm{M} \mathrm{NaCN}$

David Collins
David Collins
Numerade Educator
03:52

Problem 106

Calculate the $\mathrm{pH}$ of each of the following solutions.
a. $0.12 \mathrm{M} \mathrm{KNO}_{2}$
c. $0.40 \mathrm{M} \mathrm{NH}_{4} \mathrm{ClO}_{4}$
b. $0.45 \mathrm{M} \mathrm{NaOCl}$

David Collins
David Collins
Numerade Educator
View

Problem 107

An unknown salt is either $\mathrm{NaCN}, \mathrm{NaC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}, \mathrm{NaF}, \mathrm{NaCl}$, of $\mathrm{NaOCl}$. When $0.100 \mathrm{~mol}$ of the salt is dissolved in $1.00 \mathrm{~L}$ of solution, the $\mathrm{pH}$ of the solution is $8.07$. What is the identity of the salt?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:18

Problem 108

Consider a solution of an unknown salt having the general formula $\mathrm{BHCl}$, where $\mathrm{B}$ is one of the weak bases in Table $14.3 . \mathrm{A}$ $0.10 \mathrm{M}$ solution of the unknown salt has a pH of $5.82 .$ What is the actual formula of the salt?

James Irizarry
James Irizarry
Numerade Educator
01:36

Problem 109

Calculate the $\mathrm{pH}$ of a $0.050 \mathrm{M} \mathrm{Al}\left(\mathrm{NO}_{3}\right)_{3}$ solution. The $K_{u}$ value for $\mathrm{Al}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}^{3+}$ is $1.4 \times 10^{-5}$

David Collins
David Collins
Numerade Educator
01:31

Problem 110

Calculate the $\mathrm{pH}$ of a $0.10 \mathrm{M} \mathrm{CoCl}_{3}$ solution. The $K_{\alpha}$ value for $\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}^{3+}$ is $1.0 \times 10^{-5}$

David Collins
David Collins
Numerade Educator
01:19

Problem 111

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 $K_{a}$ and $K_{\mathrm{b}}$ values are found in Tables $14.2$ and $14.3$.
a. $\mathrm{NaNO}_{3}$
c. $\mathrm{C}_{5} \mathrm{H}_{5} \mathrm{NHClO}_{4}$
e. $\mathrm{KOCl}$
b. $\mathrm{NaNO}_{2}$
d. $\mathrm{NH}_{4} \mathrm{NO}_{2}$
f. $\mathrm{NH}_{4} \mathrm{OCl}$

Anand Jangid
Anand Jangid
Numerade Educator
View

Problem 112

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 $K_{a}$ and $K_{\mathrm{b}}$ values are found in Tables $14.2$ and $14.3 .$
a. KCl
c. $\mathrm{CH}_{3} \mathrm{NH}_{3} \mathrm{Cl}$
c. $\mathrm{NH}_{4} \mathrm{~F}$
b. $\mathrm{NH}_{4} \mathrm{C}_{2} \mathrm{H}_{3} \mathrm{O}_{2}$
d. $\overline{K F}$
f. $\mathrm{CH}_{3} \mathrm{NH}_{3} \mathrm{CN}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:27

Problem 113

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. HOCl, 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
03:37

Problem 114

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
James Irizarry
Numerade Educator
View

Problem 115

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
05:10

Problem 116

Using your results from Exercise 115, 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
James Irizarry
Numerade Educator
View

Problem 117

Will the following oxides give acidic, basic, or neutral solutions when dissolved in water? Write reactions to justify your answers.
a. $\mathrm{CaO}$
b. $\mathrm{SO}_{2}$
c. $\mathrm{Cl}_{2} \mathrm{O}$

Anatole Borisov
Anatole Borisov
Numerade Educator
02:13

Problem 118

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. $\mathrm{Sr} \mathrm{O}$

James Irizarry
James Irizarry
Numerade Educator
02:40

Problem 119

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
01:32

Problem 120

Identify the Lewis acid and the Lewis base in each of the following reactions.
a. $\mathrm{Fe}^{3+}(a q)+6 \mathrm{H}_{2} \mathrm{O}(I) \rightleftharpoons \mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}^{3+}(a q)$
b. $\mathrm{H}_{2} \mathrm{O}(l)+\mathrm{CN}^{-}(a q) \rightleftharpoons \mathrm{HCN}(a q)+\mathrm{OH}^{-}(a q)$
c. $\mathrm{Hgl}_{2}(s)+2 \mathrm{I}^{-}(a q) \rightleftharpoons \mathrm{Hgl}_{4}{ }^{2-}(a q)$

Anand Jangid
Anand Jangid
Numerade Educator
01:19

Problem 121

Aluminum hydroxide is an amphoteric substance. It can act as either a Bronsted-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 $\mathrm{OH}^{-}$.

Anand Jangid
Anand Jangid
Numerade Educator
01:07

Problem 122

Zinc hydroxide is an amphoteric substance. Write equations that describe $\mathrm{Zn}(\mathrm{OH})_{2}$ acting as a Brónsted-Lowry base toward $\mathrm{H}^{+}$ and as a Lewis acid toward $\mathrm{OH}^{-}$.

Ronald Prasad
Ronald Prasad
Numerade Educator
01:46

Problem 123

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

Anatole Borisov
Anatole Borisov
Numerade Educator
02:29

Problem 124

Use the Lewis acid-base model to explain the following reaction.
$$
\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(l) \longrightarrow \mathrm{H}_{2} \mathrm{CO}_{3}(a q)
$$

James Irizarry
James Irizarry
Numerade Educator
03:32

Problem 125

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

Anatole Borisov
Anatole Borisov
Numerade Educator
01:35

Problem 126

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
Sima Sarker
Numerade Educator
05:36

Problem 127

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

Ronald Prasad
Ronald Prasad
Numerade Educator
09:21

Problem 128

You have $100.0 \mathrm{~g}$ of saccharin, a sugar substitute, and you want to prepare a $\mathrm{pH}=5.75$ solution. What volume of solution can be prepared? For saccharin, $\mathrm{HC}_{7} \mathrm{H}_{4} \mathrm{NSO}_{3}, \mathrm{p} K_{\mathrm{a}}=11.70\left(\mathrm{p} K_{u}=\right.$
$\left.-\log K_{2}\right)$

Shalini Tyagi
Shalini Tyagi
Numerade Educator
View

Problem 129

A solution is tested for $\mathrm{pH}$ and conductivity as pictured below:
The solution contains one of the following substances: $\mathrm{HCl}$. $\mathrm{NaOH}, \mathrm{NH}_{4} \mathrm{Cl}, \mathrm{HCN}, \mathrm{NH}_{3}, \mathrm{HF}$, or $\mathrm{NaCN}$. If the solute concen-
tration is about $1.0 M$, what is the identity of the solute?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:16

Problem 130

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

James Irizarry
James Irizarry
Numerade Educator
02:53

Problem 131

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
View

Problem 132

Calculate the $\mathrm{pH}$ and $\left[\mathrm{S}^{2-}\right]$ in a $0.10 \mathrm{M} \mathrm{H}_{2} \mathrm{~S}$ solution. Assume $K_{\mathrm{a}_{1}}=1.0 \times 10^{-7} ; \boldsymbol{K}_{\Delta_{\mathrm{x}}}=1.0 \times 10^{-19}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
11:26

Problem 133

A typical vitamin C tablet (containing pure ascorbic acid, $\mathrm{H}_{2} \mathrm{C}_{6} \mathrm{H}_{6} \mathrm{O}_{6}$ ) weighs $500 . \mathrm{mg}$. One vitamin C tablet is dissolved n enough water to make $200.0 \mathrm{~mL}$ of solution. Calculate the $\mathrm{pH}$ of this solution. Ascorbic acid is a diprotic acid.

Shalini Tyagi
Shalini Tyagi
Numerade Educator
08:52

Problem 134

Calculate the $\mathrm{pH}$ of an aqueous solution containing $1.0 \times 10^{-2} M$ $\mathrm{HCl}, 1.0 \times 10^{-2} \mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$, and $1.0 \times 10^{-2} \mathrm{M} \mathrm{HCN}$

James Irizarry
James Irizarry
Numerade Educator
06:07

Problem 135

Acrylic acid $\left(\mathrm{CH}_{2}=\mathrm{CHCO}_{2} \mathrm{H}\right)$ is a precursor for many important plastics. $K_{a}$ for acrylic acid is $5.6 \times 10^{-5}$.
a. Calculate the $\mathrm{pH}$ of a $0.10 M$ solution of acrylic acid.
b. Calculate the percent dissociation of a $0.10 \mathrm{M}$ solution of acrylic acid.
c. Calculate the pH of a $0.050 M$ solution of sodium acrylate $\left(\mathrm{NaC}_{3} \mathrm{H}_{3} \mathrm{O}_{2}\right)$

Anatole Borisov
Anatole Borisov
Numerade Educator
05:14

Problem 136

A $0.20 M$ sodium chlorobenzoate $\left(\mathrm{NaC}_{7} \mathrm{H}_{4} \mathrm{ClO}_{2}\right)$ solution has a $\mathrm{pH}$ of $8.65 .$ Calculate the $\mathrm{pH}$ of a $0.20 \mathrm{M}$ chlorobenzoic acid $\left(\mathrm{HC}_{7} \mathrm{H}_{4} \mathrm{ClO}_{2}\right)$ solution.

Ronald Prasad
Ronald Prasad
Numerade Educator
02:40

Problem 137

The equilibrium constant $K_{\mathrm{a}}$ for the reaction
$\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}^{3+}(a q)+\mathrm{H}_{2} \mathrm{O}(l) \rightleftharpoons$
$\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{5}(\mathrm{OH})^{2+}(a q)+\mathrm{H}_{3} \mathrm{O}^{+}(a q)$
is $6.0 \times 10^{-3}$
a. Calculate the $\mathrm{pH}$ 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 $1.0 M$ solution of iron(III) nitrate? Explain.

Anatole Borisov
Anatole Borisov
Numerade Educator
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Problem 138

Rank the following $0.10 M$ solutions in order of increasing $\mathrm{pH}$.
a. HI, HF, NaF, Nal
b. $\mathrm{NH}_{4} \mathrm{Br}, \mathrm{HBr}, \mathrm{KBr}, \mathrm{NH}_{3}$
c. $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{3} \mathrm{NO}_{3}, \mathrm{NaNO}_{3}, \mathrm{NaOH}, \mathrm{HOC}_{6} \mathrm{H}_{5}, \mathrm{KOC}_{6} \mathrm{H}_{5}, \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}$,
$\mathrm{HNO}_{3}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:38

Problem 139

Is an aqueous solution of $\mathrm{NaHSO}_{4}$ acidic, basic, or neutral? What reaction occurs with water? Calculate the $\mathrm{pH}$ of a $0.10 \mathrm{M}$ solution of $\mathrm{NaHSO}_{4}$.

Anand Jangid
Anand Jangid
Numerade Educator
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Problem 140

Calculate $\left[\mathrm{CO}_{3}^{2-}\right]$ in a $0.010 M$ solution of $\mathrm{CO}_{2}$ in water $\left(\mathrm{H}_{2} \mathrm{CO}_{3}\right) .$ 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?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
07:47

Problem 141

Hemoglobin (abbreviated $\mathrm{Hb}$ ) 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 $\mathrm{pH}$ 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 oxygen-binding equilibrium? How does breathing into a paper bag help to counteract this effect?
c. When a person has suffered a cardiac arrest, injection of a sodium bicarbonate solution is given. Why is this necessary?

Julian Taurozzi
Julian Taurozzi
Numerade Educator
04:05

Problem 142

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
James Irizarry
Numerade Educator
05:43

Problem 143

Students are often surprised to learn that organic acids, such as acetic acid, contain - OH groups. Actually, all oxyacids contain hydroxyl groups. Sulfuric acid, usually written as $\mathrm{H}_{2} \mathrm{SO}_{4}$, has the structural formula $\mathrm{SO}_{2}(\mathrm{OH})_{2}$, where $\mathrm{S}$ is the central atom. Identify the acids whose structural formulas are shown below. Why do they behave as acids, while $\mathrm{NaOH}$ and $\mathrm{KOH}$ are bases?
a. $\mathrm{SO}(\mathrm{OH})_{2}$
b. $\mathrm{ClO}_{2}(\mathrm{OH})$
c. $\mathrm{HPO}(\mathrm{OH})_{2}$

Ian Kaigh
Ian Kaigh
Numerade Educator
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Problem 144

The pH of $1.0 \times 10^{-8} M$ hydrochloric acid is not $8.00$. The correct $\mathrm{pH}$ can be calculated by considering the relationship between the molarities of the three principal ions in the solution $\left(\mathrm{H}^{+}\right.$, $\mathrm{Cl}^{-}$, 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 $K_{\mathrm{u}}$. Calculate the $\mathrm{pH}$ of a $1.0 \times 10^{-8} \mathrm{HCl}$ solution.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:43

Problem 145

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

Ronald Prasad
Ronald Prasad
Numerade Educator
01:04

Problem 146

Calculate $\left[\mathrm{OH}^{-}\right]$ in a $3.0 \times 10^{-7} \mathrm{M}$ solution of $\mathrm{Ca}(\mathrm{OH})_{2}$.

James Irizarry
James Irizarry
Numerade Educator
05:56

Problem 147

Consider $50.0 \mathrm{~mL}$ of a solution of weak acid HA = $K_{\mathrm{a}}\left(1.00 \times 10^{-6}\right)$, 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
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Problem 148

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

Susan Hallstrom
Susan Hallstrom
Numerade Educator
06:07

Problem 149

Calculate the $\mathrm{pH}$ of a $0.200 M$ solution of $\mathrm{C}_{s} \mathrm{H}_{5} \mathrm{NHF}$. 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 prin-
cipal equilibrium in this solution is the best acid reacting with the best base; the reaction for the principal equilibrium is
$\begin{aligned} \mathrm{C}_{5} \mathrm{H}_{5} \mathrm{NH}^{+}(a q)+\mathrm{F}^{-}(a q) & \rightleftharpoons \\ \mathrm{C}_{5} \mathrm{H}_{5} \mathrm{~N}(a q)+\mathrm{HF}(a q) & K=8.2 \times 10^{-3} \end{aligned}$

Ronald Prasad
Ronald Prasad
Numerade Educator
08:23

Problem 150

Determine the $\mathrm{pH}$ of a $0.50 \mathrm{M}$ solution of $\mathrm{NH}_{4} \mathrm{OCl}$. See Exercise 149 .

Shalini Tyagi
Shalini Tyagi
Numerade Educator
03:37

Problem 151

Calculate $\left[\mathrm{OH}^{-}\right]$ in a solution obtained by adding $0.0100 \mathrm{~mol}$ of solid $\mathrm{NaOH}$ to $1.00 \mathrm{~L}$ of $15.0 \mathrm{M} \mathrm{NH}_{3}$

Anatole Borisov
Anatole Borisov
Numerade Educator
04:27

Problem 152

What mass of $\mathrm{NaOH}(s)$ must be added to $1.0 \mathrm{~L}$ of $0.050 \mathrm{M} \mathrm{NH}_{3}$ to ensure that the percent ionization of $\mathrm{NH}_{3}$ is no greater than $0.0010 \%$ ? Assume no volume change on addition of $\mathrm{NaOH}$.

James Irizarry
James Irizarry
Numerade Educator
03:48

Problem 153

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 $1.00 \mathrm{~atm}$. When $1.50 \mathrm{~g}$ of this acid is dissolved in enough water to make $100.0 \mathrm{~mL}$ of solution, the $\mathrm{pH}$ is found to be $1.80 .$ Calculate $K_{\mathrm{a}}$ for the acid.

Anatole Borisov
Anatole Borisov
Numerade Educator
08:05

Problem 154

Calculate the mass of sodium hydroxide that must be added to $1.00 \mathrm{~L}$ of $1.00 \mathrm{M} \mathrm{HC}_{2} \mathrm{H}_{3} \mathrm{O}_{2}$ to double the $\mathrm{pH}$ of the solution
(assume that the NaOH does not change the volume of the solution).

Tracy Tourville
Tracy Tourville
Numerade Educator
03:11

Problem 155

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
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Problem 156

Calculate the pH of a $0.10 M$ solution of sodium phosphate. See Exercise 155 .

Susan Hallstrom
Susan Hallstrom
Numerade Educator
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Problem 157

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

Susan Hallstrom
Susan Hallstrom
Numerade Educator
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Problem 158

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 $\mathrm{pH}$ of the solution in terms of $K_{\mathrm{a}_{1}}$ and $K_{\iota_{2}}$ using the result from part b.
d. What is the $\mathrm{pH}$ of a solution of $\mathrm{NaHCO}_{3}$ ?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
08:11

Problem 159

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

Shalini Tyagi
Shalini Tyagi
Numerade Educator
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Problem 160

A sample containing $0.0500 \mathrm{~mol}$ of $\mathrm{Fe}_{2}\left(\mathrm{SO}_{4}\right)_{3}$ is dissolved in enough water to make $1.00 \mathrm{~L}$ of solution. This solution contains hydrated $\mathrm{SO}_{4}^{2-}$ and $\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}{ }^{3+}$ 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 $6.73 \mathrm{~atm}$ at $25^{\circ} \mathrm{C} .$ Calculate $K_{a}$ 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 goes through the semipermeable membrane. Actually, this is not a great assumption for the tiny $\mathrm{H}^{+}$ ion.)

Susan Hallstrom
Susan Hallstrom
Numerade Educator
03:51

Problem 161

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

Anatole Borisov
Anatole Borisov
Numerade Educator
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Problem 162

Isocyanic acid (HNCO) can be prepared by heating sodium cyanate in the presence of solid oxalic acid according to the equation
$$
2 \mathrm{NaOCN}(s)+\mathrm{H}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(s) \longrightarrow 2 \mathrm{HNCO}(t)+\mathrm{Na}_{2} \mathrm{C}_{2} \mathrm{O}_{4}(s)
$$
Upon isolating pure $\mathrm{HNCO}(l)$, an aqueous solution of $\mathrm{HNCO}$ can be prepared by dissolving the liquid HNCO in water. What is the pH of a 100.-mL solution of HNCO prepared from the reaction of $10.0 \mathrm{~g}$ each of $\mathrm{NaOCN}$ 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 $\left.\mathrm{HNCO}=1.2 \times 10^{-4} .\right)$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:42

Problem 163

Papaverine hydrochloride (abbreviated 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 $\mathrm{pH}$ of a $30.0 \mathrm{mg} / \mathrm{mL}$ aqueous dose of $\mathrm{papH}^{+} \mathrm{Cl}^{-}$ prepared at $35.0^{\circ} \mathrm{C} . K_{w}$ at $35.0^{\circ} \mathrm{C}$ is $2.1 \times 10^{-14}$.

James Irizarry
James Irizarry
Numerade Educator
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Problem 164

Captain Kirk, of the Starship Enterprise, has been told by his superiors that only a chemist can be trusted with the combination to the safe containing the dilithium crystals that power the ship. The combination is the $\mathrm{pH}$ of solution A, described below, followed by the $\mathrm{pH}$ of solution $\mathrm{C}$. (Example: If the $\mathrm{pH}$ of solution $\mathrm{A}$ is $3.47$ and that of solution $\mathrm{C}$ is $8.15$, then the combination to the safe is $3-47-8-15 .$ The chemist must determine the combination using only the information below (all solutions are at $25^{\circ} \mathrm{C}$ ):
Solution $\mathrm{A}$ is $50.0 \mathrm{~mL}$ of a $0.100 \mathrm{M}$ solution of the weak monoprotic acid HX. Solution $\mathrm{B}$ is a $0.0500 \mathrm{M}$ solution of the salt $\mathrm{NaX}$. It has a $\mathrm{pH}$ of $10.02$. Solution $\mathrm{C}$ is made by adding $15.0 \mathrm{~mL}$ of $0.250 \mathrm{M} \mathrm{KOH}$ to soIution A. What is the combination to the safe?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
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Problem 165

For the following, mix equal volumes of one solution from Group I with one solution from Group II to achieve the indicated $\mathrm{pH}$. Calculate the $\mathrm{pH}$ of each solution.
Group I: $0.20 \mathrm{M} \mathrm{NH}_{4} \mathrm{Cl}, 0.20 \mathrm{M} \mathrm{HCl}, 0.20 \mathrm{M} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{3} \mathrm{Cl}, 0.20$
$M\left(\mathrm{C}_{2} \mathrm{H}_{5}\right)_{3} \mathrm{NHCl}$
Group II: $0.20 \mathrm{M} \mathrm{KOI}, 0.20 \mathrm{M} \mathrm{NaCN}, 0.20 \mathrm{M} \mathrm{KOCl}, 0.20 \mathrm{M}$
$\mathrm{NaNO}_{2}$
a. the solution with the lowest $\mathrm{pH}$
b. the solution with the highest $\mathrm{pH}$
c. the solution with the pH closest to $7.00$

Susan Hallstrom
Susan Hallstrom
Numerade Educator