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Chemistry

Steven S. Zumdahl, Susan A. Zumdahl

Chapter 18

Electrochemistry - all with Video Answers

Educators

Chapter Questions

06:57

Problem 1

Sketch a galvanic cell, and explain how it works. Look at Figs. $18.1$ and $18.2 .$ Explain what is occurring in each container and why the cell in Fig. $18.2$ "works" but the one in Fig. $18.1$ does not.

Margaret Calhoun
Margaret Calhoun
Numerade Educator
05:14

Problem 2

In making a specific galvanic cell, explain how one decides on the electrodes and the solutions to use in the cell.

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
00:55

Problem 3

You want to "plate out" nickel metal from a nickel nitrate solution onto a piece of metal inserted into the solution. Should you use copper or zinc? Explain.

David Collins
David Collins
Numerade Educator
02:41

Problem 4

A copper penny can be dissolved in nitric acid but not in hydrochloric acid. Using reduction potentials from the book, show why this is so. What are the products of the reaction? Newer pennies contain a mixture of zinc and copper. What happens to the zinc in the penny when the coin is placed in nitric acid? Hydrochloric acid? Support your explanations with data from the book, and include balanced equations for all reactions.

David Collins
David Collins
Numerade Educator
00:59

Problem 5

Sketch a cell that forms iron metal from iron(II) while changing chromium metal to chromium(III). Calculate the voltage, show the electron flow, label the anode and cathode, and balance the overall cell equation.

David Collins
David Collins
Numerade Educator
02:27

Problem 6

Which of the following is the best reducing agent: $\mathrm{F}_{2}, \mathrm{H}_{2}, \mathrm{Na}$, $\mathrm{Na}^{+}, \mathrm{F}^{-}$ ? Explain. Order as many of these species as possible from the best to the worst oxidizing agent. Why can't you order all of them? From Table $18.1$ choose the species that is the best oxidizing agent. Choose the best reducing agent. Explain.

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
04:40

Problem 7

You are told that metal $\mathrm{A}$ is a better reducing agent than metal $\mathrm{B}$. What, if anything, can be said about $\mathrm{A}^{+}$ and $\mathrm{B}^{+}$ ? Explain.

Margaret Calhoun
Margaret Calhoun
Numerade Educator
02:05

Problem 8

Explain the following relationships: $\Delta G$ and $w$, cell potential and $w$, cell potential and $\Delta G$, cell potential and $Q .$ Using these relationships, explain how you could make a cell in which both electrodes are the same metal and both solutions contain the same compound, but at different concentrations. Why does such a cell run spontaneously?

David Collins
David Collins
Numerade Educator
01:13

Problem 9

Explain why cell potentials are not multiplied by the coefficients in the balanced redox equation. (Use the relationship between $\Delta G$ and cell potential to do this.)

David Collins
David Collins
Numerade Educator
01:02

Problem 10

What is the difference between $\mathscr{E}$ and $\mathscr{\zeta}^{\circ} ?$ When is 8 equal to zero? When is $\mathscr{\zeta}^{\circ}$ equal to zero? (Consider "regular" galvanic cells as well as concentration cells.)

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
10:13

Problem 11

Consider the following galvanic cell: What happens to $\mathscr{C}$ as the concentration of $\mathrm{Zn}^{2+}$ is increased? As the concentration of $\mathrm{Ag}^{+}$ is increased? What happens to $8^{\circ}$ in these cases?

Margaret Calhoun
Margaret Calhoun
Numerade Educator
02:09

Problem 12

Look up the reduction potential for $\mathrm{Fe}^{3+}$ to $\mathrm{Fe}^{2+}$. Look up the reduction potential for $\mathrm{Fe}^{2+}$ to Fe. Finally, look up the reduction potential for $\mathrm{Fe}^{3+}$ to Fe. You should notice that adding the reduction potentials for the first two does not give the potential for the third. Why not? Show how you can use the first two potentials to calculate the third potential.

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
00:37

Problem 13

If the cell potential is proportional to work and the standard reduction potential for the hydrogen ion is zero, does this mean that the reduction of the hydrogen ion requires no work?

David Collins
David Collins
Numerade Educator
00:54

Problem 14

Is the following statement true or false? Concentration cells work because standard reduction potentials are dependent on concentration. Explain.

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
04:38

Problem 15

Define oxidation and reduction in terms of both change in oxidation number and electron loss or gain.

Margaret Calhoun
Margaret Calhoun
Numerade Educator
02:32

Problem 16

Assign oxidation numbers to all the atoms in each of the following.
a. $\mathrm{HNO}_{3}$
e. $\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}$
i. $\mathrm{Na}_{2} \mathrm{C}_{2} \mathrm{O}_{4}$
b. $\mathrm{CuCl}_{2}$
f. Ag
j. $\mathrm{CO}_{2}$
c. $\mathrm{O}_{2}$
g. $\mathrm{PbSO}_{4}$
k. $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{Ce}\left(\mathrm{SO}_{4}\right)_{3}$
d. $\mathrm{H}_{2} \mathrm{O}_{2}$
h. $\mathrm{PbO}_{2}$
1. $\mathrm{Cr}_{2} \mathrm{O}_{3}$

Lottie Adams
Lottie Adams
Numerade Educator
13:50

Problem 17

Specify which of the following equations represent oxidationreduction reactions, and indicate the oxidizing agent, the reducing agent, the species being oxidized, and the species being reduced.
a. $\mathrm{CH}_{4}(g)+\mathrm{H}_{2} \mathrm{O}(g) \rightarrow \mathrm{CO}(g)+3 \mathrm{H}_{2}(g)$
b. $2 \mathrm{AgNO}_{3}(a q)+\mathrm{Cu}(s) \rightarrow \mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}(a q)+2 \mathrm{Ag}(s)$
c. $\mathrm{Zn}(s)+2 \mathrm{HCl}(a q) \rightarrow \mathrm{ZnCl}_{2}(a q)+\mathrm{H}_{2}(g)$
d. $2 \mathrm{H}^{+}(a q)+2 \mathrm{CrO}_{4}^{2-}(a q) \rightarrow \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+\mathrm{H}_{2} \mathrm{O}(l)$

Margaret Calhoun
Margaret Calhoun
Numerade Educator
01:42

Problem 18

The Ostwald process for the commercial production of nitric acid involves the following three steps:
$$\begin{aligned}4 \mathrm{NH}_{3}(g)+5 \mathrm{O}_{2}(g) & \longrightarrow 4 \mathrm{NO}(g)+6 \mathrm{H}_{2} \mathrm{O}(g) \\
2 \mathrm{NO}(g)+\mathrm{O}_{2}(g) & \longrightarrow 2 \mathrm{NO}_{2}(g) \\
3 \mathrm{NO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l) & \longrightarrow 2 \mathrm{HNO}_{3}(a q)+\mathrm{NO}(g)
\end{aligned}$$
a. Which reactions in the Ostwald process are oxidationreduction reactions?
b. Identify each oxidizing agent and reducing agent.

David Collins
David Collins
Numerade Educator
13:52

Problem 19

What is electrochemistry? What are redox reactions? Explain the difference between a galvanic and an electrolytic cell.

Margaret Calhoun
Margaret Calhoun
Numerade Educator
01:37

Problem 20

When balancing reactions in Chapter 3 , we did not mention that reactions must be charge balanced as well as mass balanced. What do charge balanced and mass balanced mean? How are redox reactions charge balanced?

Anand Jangid
Anand Jangid
Numerade Educator
01:06

Problem 21

When magnesium metal is added to a beaker of $\mathrm{HCl}(a q)$, a gas is produced. Knowing that magnesium is oxidized and that hydrogen is reduced, write the balanced equation for the reaction. How many electrons are transferred in the balanced equation? What quantity of useful work can be obtained when $\mathrm{Mg}$ is added directly to the beaker of HCl? How can you harness this reaction to do useful work?

David Collins
David Collins
Numerade Educator
00:53

Problem 22

How can one construct a galvanic cell from two substances, each having a negative standard reduction potential?

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
09:11

Problem 23

The free energy change for a reaction, $\Delta G$, is an extensive property. What is an extensive property? Surprisingly, one can calculate $\Delta G$ from the cell potential, $\mathscr{b}$, for the reaction. This is surprising because $\mathscr{B}$ is an intensive property. How can the extensive property $\Delta G$ be calculated from the intensive property $\mathscr{E}$ ?

Margaret Calhoun
Margaret Calhoun
Numerade Educator
00:59

Problem 24

What is wrong with the following statement: The best concentration cell will consist of the substance having the most positive standard reduction potential. What drives a concentration cell to produce a large voltage?

David Collins
David Collins
Numerade Educator
00:32

Problem 25

. When jump-starting a car with a dead battery, the ground jumper should be attached to a remote part of the engine block. Why?

David Collins
David Collins
Numerade Educator
01:04

Problem 26

In theory, most metals should easily corrode in air. Why? A group of metals called the noble metals are relatively difficult to corrode in air. Some noble metals include gold, platinum, and silver. Reference Table $18.1$ to come up with a possible reason why the noble metals are relatively difficult to corrode.

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
01:26

Problem 27

Consider the electrolysis of a molten salt of some metal. What information must you know to calculate the mass of metal plated out in the electrolytic cell?

David Collins
David Collins
Numerade Educator
09:08

Problem 28

Although aluminum is one of the most abundant elements on earth, production of pure Al proved very difficult until the late 1800 s. At this time, the Hall-Heroult process made it relatively easy to produce pure Al. Why was pure Al so difficult to produce and what was the key discovery behind the Hall-Heroult process?

Shalini Tyagi
Shalini Tyagi
Numerade Educator
06:45

Problem 29

Balance the following oxidation-reduction reactions that occur in acidic solution using the half-reaction method.
a. $\mathrm{I}^{-}(a q)+\mathrm{ClO}^{-}(a q) \rightarrow \mathrm{I}_{3}^{-}(a q)+\mathrm{Cl}^{-}(a q)$
b. $\mathrm{As}_{2} \mathrm{O}_{3}(s)+\mathrm{NO}_{3}^{-}(a q) \rightarrow \mathrm{H}_{3} \mathrm{AsO}_{4}(a q)+\mathrm{NO}(g)$
c. $\mathrm{Br}^{-}(a q)+\mathrm{MnO}_{4}^{-}(a q) \rightarrow \mathrm{Br}_{2}(l)+\mathrm{Mn}^{2+}(a q)$
d. $\mathrm{CH}_{3} \mathrm{OH}(a q)+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q) \rightarrow \mathrm{CH}_{2} \mathrm{O}(a q)+\mathrm{Cr}^{3+}(a q)$

David Collins
David Collins
Numerade Educator
06:37

Problem 30

Balance the following oxidation-reduction reactions that occur in acidic solution using the half-reaction method.
a. $\mathrm{Cu}(s)+\mathrm{NO}_{3}^{-}(a q) \rightarrow \mathrm{Cu}^{2+}(a q)+\mathrm{NO}(g)$
b. $\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+\mathrm{Cl}^{-}(a q) \rightarrow \mathrm{Cr}^{3+}(a q)+\mathrm{Cl}_{2}(g)$
c. $\mathrm{Pb}(s)+\mathrm{PbO}_{2}(s)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q) \rightarrow \mathrm{PbSO}_{4}(s)$
d. $\mathrm{Mn}^{2+}(a q)+\mathrm{NaBiO}_{3}(s) \rightarrow \mathrm{Bi}^{3+}(a q)+\mathrm{MnO}_{4}^{-}(a q)$
e. $\mathrm{H}_{3} \mathrm{AsO}_{4}(a q)+\mathrm{Zn}(s) \rightarrow \operatorname{AsH}_{3}(g)+\mathrm{Zn}^{2+}(a q)$

David Collins
David Collins
Numerade Educator
05:26

Problem 31

Balance the following oxidation-reduction reactions that occur in basic solution.
a. $\mathrm{Al}(s)+\mathrm{MnO}_{4}^{-}(a q) \rightarrow \mathrm{MnO}_{2}(s)+\mathrm{Al}(\mathrm{OH})_{4}^{-}(a q)$
b. $\mathrm{Cl}_{2}(\mathrm{~g}) \rightarrow \mathrm{Cl}^{-}(a q)+\mathrm{OCl}^{-}(a q)$
c. $\mathrm{NO}_{2}^{-}(a q)+\mathrm{Al}(s) \rightarrow \mathrm{NH}_{3}(g)+\mathrm{AlO}_{2}^{-}(a q)$

David Collins
David Collins
Numerade Educator
06:04

Problem 32

Balance the following oxidation-reduction reactions that occur in basic solution.
a. $\mathrm{Cr}(s)+\mathrm{CrO}_{4}^{2-}(a q) \rightarrow \mathrm{Cr}(\mathrm{OH})_{3}(s)$
b. $\mathrm{MnO}_{4}^{-}(a q)+\mathrm{S}^{2-}(a q) \rightarrow \mathrm{MnS}(s)+\mathrm{S}(s)$
c. $\mathrm{CN}^{-}(a q)+\mathrm{MnO}_{4}^{-}(a q) \rightarrow \mathrm{CNO}^{-}(a q)+\mathrm{MnO}_{2}(s)$

David Collins
David Collins
Numerade Educator
01:24

Problem 33

Chlorine gas was first prepared in 1774 by C. W. Scheele by oxidizing sodium chloride with manganese(IV) oxide. The reaction is $\mathrm{NaCl}(a q)+\mathrm{H}_{2} \mathrm{SO}_{4}(a q)+\mathrm{MnO}_{2}(s) \longrightarrow$
$\mathrm{Na}_{2} \mathrm{SO}_{4}(a q)+\mathrm{MnCl}_{2}(a q)+\mathrm{H}_{2} \mathrm{O}(l)+\mathrm{Cl}_{2}(g)$ Balance this equation.

William Mills
William Mills
Numerade Educator
01:04

Problem 34

Gold metal will not dissolve in either concentrated nitric acid on concentrated hydrochloric acid. It will dissolve, however, in aqua regia, a mixture of the two concentrated acids. The products of the reaction are the $\mathrm{AuCl}_{4}^{-}$ ion and gaseous NO. Write a balanced equation for the dissolution of gold in aqua regia.

David Collins
David Collins
Numerade Educator
03:20

Problem 35

Sketch the galvanic cells based on the following overall reactions. Show the direction of electron flow and identify the cathode and anode. Give the overall balanced equation. Assume that all concentrations are $1.0 M$ and that all partial pressures are $1.0 \mathrm{~atm}$.
a. $\mathrm{Cr}^{3+}(a q)+\mathrm{Cl}_{2}(g) \rightleftharpoons \mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+\mathrm{Cl}^{-}(a q)$
b. $\mathrm{Cu}^{2+}(a q)+\mathrm{Mg}(s) \rightleftharpoons \mathrm{Mg}^{2+}(a q)+\mathrm{Cu}(s)$

David Collins
David Collins
Numerade Educator
03:30

Problem 36

Sketch the galvanic cells based on the following overall reactions. Show the direction of electron flow, the direction of ion migration through the salt bridge, and identify the cathode and anode. Give the overall balanced equation. Assume that all concentrations are $1.0 M$ and that all partial pressures are $1.0 \mathrm{~atm}$.
a. $\mathrm{IO}_{3}^{-}(a q)+\mathrm{Fe}^{2+}(a q) \rightleftharpoons \mathrm{Fe}^{3+}(a q)+\mathrm{I}_{2}(a q)$
b. $\mathrm{Zn}(s)+\mathrm{Ag}^{+}(a q) \rightleftharpoons \mathrm{Zn}^{2+}(a q)+\mathrm{Ag}(s)$

David Collins
David Collins
Numerade Educator
02:26

Problem 37

Calculate $\mathscr{C}^{\circ}$ values for the galvanic cells in Exercise 35 .

David Collins
David Collins
Numerade Educator
00:27

Problem 38

Calculate $\mathscr{E}^{\circ}$ values for the galvanic cells in Exercise 36 .

David Collins
David Collins
Numerade Educator
04:25

Problem 39

Sketch the galvanic cells based on the following half-reactions. Show the direction of electron flow, show the direction of ion migration through the salt bridge, and identify the cathode and anode. Give the overall balanced equation, and determine $\mathscr{E}^{\circ}$ for the galvanic cells. Assume that all concentrations are $1.0 M$ and that all partial pressures are $1.0 \mathrm{~atm}$.
a. $\mathrm{Cl}_{2}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cl}^{-} \quad \mathscr{E}^{\circ}=1.36 \mathrm{~V}$
$\mathrm{Br}_{2}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{Br}^{-} \quad 8^{\circ}=1.09 \mathrm{~V}$
b. $\mathrm{MnO}_{4}^{-}+8 \mathrm{H}^{+}+5 \mathrm{e}^{-} \rightarrow \mathrm{Mn}^{2+}+4 \mathrm{H}_{2} \mathrm{O}$
$\mathscr{b}^{\circ}=1.51 \mathrm{~V}$
$\mathrm{IO}_{4}^{-}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow \mathrm{IO}_{3}^{-}+\mathrm{H}_{2} \mathrm{O} \quad \mathscr{E ^ { \circ }}=1.60 \mathrm{~V}$

Crystal Wang
Crystal Wang
Numerade Educator
02:09

Problem 40

Sketch the galvanic cells based on the following half-reactions. Show the direction of electron flow, show the direction of ion migration through the salt bridge, and identify the cathode and anode. Give the overall balanced equation, and determine $\mathscr{E}^{\circ}$ for the galvanic cells. Assume that all concentrations are $1.0 M$ and that all partial pressures are $1.0 \mathrm{~atm} .$ $\begin{array}{ll}\text { a. } \mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_{2} \mathrm{O} & \mathscr{6}^{\circ}=1.78 \mathrm{~V} \\ \mathrm{O}_{2}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow \mathrm{H}_{2} \mathrm{O}_{2} & \mathscr{6}^{\circ}=0.68 \mathrm{~V}\end{array}$
b. $\mathrm{Mn}^{2+}+2 \mathrm{e}^{-} \rightarrow \mathrm{Mn}$
$\mathscr{6}^{\circ}=-1.18 \mathrm{~V}$
$\mathrm{Fe}^{3+}+3 \mathrm{e}^{-} \rightarrow \mathrm{Fe} \quad \mathscr{6}^{\circ}=-0.036 \mathrm{~V}$

David Collins
David Collins
Numerade Educator
06:46

Problem 41

Give the standard line notation for each cell in Exercises 35 and $39 .$

David Collins
David Collins
Numerade Educator
01:17

Problem 42

Give the standard line notation for each cell in Exercises 36 and $40 .$

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
06:17

Problem 43

Consider the following galvanic cells: For each galvanic cell, give the balanced cell equation and determine $\mathscr{E}^{\circ} .$ Standard reduction potentials are found in Table $18.1$.

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
01:59

Problem 44

Give the balanced cell equation and determine $\mathscr{E}^{\circ}$ for the galvanic cells based on the following half-reactions. Standard reduction potentials are found in Table $18.1$. a. $\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}+14 \mathrm{H}^{+}+6 \mathrm{e}^{-} \rightarrow 2 \mathrm{Cr}^{3+}+7 \mathrm{H}_{2} \mathrm{O}$
$\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}$
b. $2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow \mathrm{H}_{2}$
$\mathrm{Al}^{3+}+3 \mathrm{e}^{-} \rightarrow \mathrm{Al}$

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
08:10

Problem 45

Calculate $\mathscr{E}^{\circ}$ values for the following cells. Which reactions are spontaneous as written (under standard conditions)? Balance the equations. Standard reduction potentials are found in Table 18.1.
a. $\mathrm{MnO}_{4}^{-}(a q)+\mathrm{I}^{-}(a q) \rightleftharpoons \mathrm{I}_{2}(a q)+\mathrm{Mn}^{2+}(a q)$
b. $\mathrm{MnO}_{4}^{-}(a q)+\mathrm{F}^{-}(a q) \rightleftharpoons \mathrm{F}_{2}(g)+\mathrm{Mn}^{2+}(a q)$

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
02:04

Problem 46

Calculate $8^{\circ}$ values for the following cells. Which reactions are spontaneous as written (under standard conditions)? Balance the equations that are not already balanced. Standard reduction potentials are found in Table $18.1$.
a. $\mathrm{H}_{2}(g) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{H}^{-}(a q)$
b. $\mathrm{Au}^{3+}(a q)+\mathrm{Ag}(s) \rightleftharpoons \mathrm{Ag}^{+}(a q)+\mathrm{Au}(s)$

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
02:04

Problem 47

Chlorine dioxide $\left(\mathrm{ClO}_{2}\right)$, which is produced by the reaction
$$2 \mathrm{NaClO}_{2}(a q)+\mathrm{Cl}_{2}(g) \longrightarrow 2 \mathrm{ClO}_{2}(g)+2 \mathrm{NaCl}(a q)$$
has been tested as a disinfectant for municipal water treatment. Using data from Table $18.1$, calculate $\underline{6}^{\circ}$ and $\Delta G^{\circ}$ at $25^{\circ} \mathrm{C}$ for the production of $\mathrm{ClO}_{2}$.

Kratika Bhadauria
Kratika Bhadauria
Numerade Educator
05:46

Problem 48

The amount of manganese in steel is determined by changing it to permanganate ion. The steel is first dissolved in nitric acid, producing $\mathrm{Mn}^{2+}$ ions. These ions are then oxidized to the deeply colored $\mathrm{MnO}_{4}^{-}$ ions by periodate ion $\left(\mathrm{IO}_{4}^{-}\right)$ in acid solution.
a. Complete and balance an equation describing each of the above reactions.
b. Calculate $\mathscr{C}^{\circ}$ and $\Delta G^{\circ}$ at $25^{\circ} \mathrm{C}$ for each reaction.

David Collins
David Collins
Numerade Educator
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Problem 49

Calculate the maximum amount of work that can be obtained from the galvanic cells at standard conditions in Exercise 43 .

Susan Hallstrom
Susan Hallstrom
Numerade Educator
View

Problem 50

Calculate the maximum amount of work that can be obtained from the galvanic cells at standard conditions in Exercise 44 .

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:22

Problem 51

Estimate $\mathscr{C}^{\circ}$ for the half-reaction
$$2 \mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_{2}+2 \mathrm{OH}^{-}$$
given the following values of $\Delta G_{\mathrm{f}}^{\circ}$ :
$$\begin{aligned}\mathrm{H}_{2} \mathrm{O}(l) &=-237 \mathrm{~kJ} / \mathrm{mol} \\
\mathrm{H}_{2}(g) &=0.0 \\\mathrm{OH}^{-}(a q) &=-157 \mathrm{~kJ} / \mathrm{mol} \\
\mathrm{e}^{-} &=0.0\end{aligned}$$
Compare this value of $\mathscr{E}^{\circ}$ with the value of $\mathscr{b}^{\circ}$ given in Table $18.1$.

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
02:59

Problem 52

The equation $\Delta G^{\circ}=-n F \mathscr{C}^{\circ}$ also can be applied to halfreactions. Use standard reduction potentials to estimate $\Delta G_{\mathrm{f}}^{\circ}$ for $\mathrm{Fe}^{2+}(a q)$ and $\mathrm{Fe}^{3+}(a q) .\left(\Delta G_{\mathrm{f}}^{\circ}\right.$ for $\left.\mathrm{e}^{-}=0 .\right)$

Lottie Adams
Lottie Adams
Numerade Educator
01:17

Problem 53

Using data from Table $18.1$, place the following in order of increasing strength as oxidizing agents (all under standard conditions).
$$\mathrm{Cd}^{2+}, \quad \mathrm{IO}_{3}^{-}, \quad \mathrm{K}^{+}, \quad \mathrm{H}_{2} \mathrm{O}, \quad \mathrm{AuCl}_{4}^{-}, \quad\mathrm{I}_{2}$$

Lottie Adams
Lottie Adams
Numerade Educator
01:54

Problem 54

Using data from Table $18.1$, place the following in order of increasing strength as reducing agents (all under standard conditions).
$$\mathrm{Cu}^{+}, \mathrm{F}^{-}, \mathrm{H}^{-}, \quad \mathrm{H}_{2} \mathrm{O}, \quad \mathrm{I}_{2}, \quad \mathrm{~K}$$

Lottie Adams
Lottie Adams
Numerade Educator
05:22

Problem 55

Answer the following questions using data from Table $18.1$ (all under standard conditions).
a. Is $\mathrm{H}^{+}(a q)$ capable of oxidizing $\mathrm{Cu}(s)$ to $\mathrm{Cu}^{2+}(a q)$ ?
b. Is $\mathrm{Fe}^{3+}(a q)$ capable of oxidizing $\mathrm{I}^{-}(a q)$ ?
c. Is $\mathrm{H}_{2}(g)$ capable of reducing $\mathrm{Ag}^{+}(a q)$ ?

Bhumika Jayee
Bhumika Jayee
Numerade Educator
02:38

Problem 56

Answer the following questions using data from Table $18.1$ (all under standard conditions).
a. Is $\mathrm{H}_{2}(g)$ capable of reducing $\mathrm{Ni}^{2+}(a q)$ ?
b. Is $\mathrm{Fe}^{2+}(a q)$ capable of reducing $\mathrm{VO}_{2}^{+}(a q)$ ?
c. Is $\mathrm{Fe}^{2+}(a q)$ capable of reducing $\mathrm{Cr}^{3+}(a q)$ to $\mathrm{Cr}^{2+}(a q)$ ?

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
09:56

Problem 57

Consider only the species (at standard conditions)
$$\mathrm{Na}^{+}, \mathrm{Cl}^{-}, \mathrm{Ag}^{+}, \mathrm{Ag}, \mathrm{Zn}^{2+}, \mathrm{Zn}, \mathrm{Pb}$$
in answering the following questions. Give reasons for your answers. (Use data from Table 18.1.)
a. Which is the strongest oxidizing agent?
b. Which is the strongest reducing agent?
c. Which species can be oxidized by $\mathrm{SO}_{4}^{2-}(a q)$ in acid?
d. Which species can be reduced by $\mathrm{Al}(s)$ ?

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
07:39

Problem 58

Consider only the species (at standard conditions)
$$\mathrm{Br}^{-}, \mathrm{Br}_{2}, \mathrm{H}^{+}, \quad \mathrm{H}_{2}, \quad \mathrm{La}^{3+}, \quad \mathrm{Ca}, \quad \mathrm{Cd}$$
in answering the following questions. Give reasons for your answers.
a. Which is the strongest oxidizing agent?
b. Which is the strongest reducing agent?
c. Which species can be oxidized by $\mathrm{MnO}_{4}^{-}$ in acid?
d. Which species can be reduced by $\mathrm{Zn}(s)$ ?

David Collins
David Collins
Numerade Educator
03:36

Problem 59

Use the table of standard reduction potentials (Table $18.1)$ to pick a reagent that is capable of each of the following oxidations (under standard conditions in acidic solution).
a. oxidize $\mathrm{Br}^{-}$ to $\mathrm{Br}_{2}$ but not oxidize $\mathrm{Cl}^{-}$ to $\mathrm{Cl}_{2}$
b. oxidize $\mathrm{Mn}$ to $\mathrm{Mn}^{2+}$ but not oxidize $\mathrm{Ni}$ to $\mathrm{Ni}^{2+}$

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
01:48

Problem 60

Use the table of standard reduction potentials (Table $18.1)$ to pick a reagent that is capable of each of the following reductions (under standard conditions in acidic solution).
a. reduce $\mathrm{Cu}^{2+}$ to $\mathrm{Cu}$ but not reduce $\mathrm{Cu}^{2+}$ to $\mathrm{Cu}^{+}$
b. reduce $\mathrm{Br}_{2}$ to $\mathrm{Br}^{-}$ but not reduce $\mathrm{I}_{2}$ to $\mathrm{I}^{-}$

Lottie Adams
Lottie Adams
Numerade Educator
01:51

Problem 61

Hydrazine is somewhat toxic. Use the half-reactions shown below to explain why household bleach (a highly alkaline solution of sodium hypochlorite) should not be mixed with household ammonia or glass cleansers that contain ammonia.
$\mathrm{ClO}^{-}+\mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{OH}^{-}+\mathrm{Cl}^{-} \quad \mathscr{E}^{\circ}=0.90 \mathrm{~V}$
$\mathrm{N}_{2} \mathrm{H}_{4}+2 \mathrm{H}_{2} \mathrm{O}+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{NH}_{3}+2 \mathrm{OH}^{-} \quad \mathscr{E}^{\circ}=-0.10 \mathrm{~V}$

Lottie Adams
Lottie Adams
Numerade Educator
02:10

Problem 62

The compound with the formula $\mathrm{TII}_{3}$ is a black solid. Given the following standard reduction potentials,
$\begin{aligned} \mathrm{Tl}^{3+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Tl}^{+} & & 8^{\circ}=1.25 \mathrm{~V} \\ \mathrm{I}_{3}^{-}+2 \mathrm{e}^{-} \longrightarrow 3 \mathrm{I}^{-} & & \mathscr{C}^{\circ} &=0.55 \mathrm{~V} \end{aligned}$
would you formulate this compound as thallium(III) iodide or thallium(I) triiodide?

Lottie Adams
Lottie Adams
Numerade Educator
01:48

Problem 63

A galvanic cell is based on the following half-reactions at $25^{\circ} \mathrm{C}$ :
$$\begin{aligned}\mathrm{Ag}^{+}+\mathrm{e}^{-} & \longrightarrow \mathrm{Ag} \\
\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} & \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}
\end{aligned}$$
Predict whether $\mathscr{G}_{\text {cell }}$ is larger or smaller than $\mathscr{C}_{\text {cell }}^{\circ}$ for the following cases.
a. $\left[\mathrm{Ag}^{+}\right]=1.0 \mathrm{M},\left[\mathrm{H}_{2} \mathrm{O}_{2}\right]=2.0 \mathrm{M},\left[\mathrm{H}^{+}\right]=2.0 \mathrm{M}$
b. $\left[\mathrm{Ag}^{+}\right]=2.0 \mathrm{M},\left[\mathrm{H}_{2} \mathrm{O}_{2}\right]=1.0 M,\left[\mathrm{H}^{+}\right]=1.0 \times 10^{-7} M$

David Collins
David Collins
Numerade Educator
01:17

Problem 64

Consider the concentration cell in Fig. $18.10$. If the $\mathrm{Fe}^{2+}$ concentration in the right compartment is changed from $0.1 M$ to $1 \times 10^{-7} M \mathrm{Fe}^{2+}$, predict the direction of electron flow, and designate the anode and cathode compartments.

David Collins
David Collins
Numerade Educator
02:03

Problem 65

Consider the concentration cell shown below. Calculate the cell potential at $25^{\circ} \mathrm{C}$ when the concentration of $\mathrm{Ag}^{+}$ in the compartment on the right is the following.
a. $1.0 \mathrm{M}$
b. $2.0 \mathrm{M}$
c. $0.10 \mathrm{M}$
d. $4.0 \times 10^{-5} M$
e. Calculate the potential when both solutions are $0.10 M$ in $\mathrm{Ag}^{+}$. For each case, also identify the cathode, the anode, and the direction in which electrons flow.

David Collins
David Collins
Numerade Educator
01:30

Problem 66

Consider a concentration cell similar to the one shown in Exercise 65 , except that both electrodes are made of $\mathrm{Ni}$ and in the left-hand compartment $\left[\mathrm{Ni}^{2+}\right]=1.0 M .$ Calculate the cell potential at $25^{\circ} \mathrm{C}$ when the concentration of $\mathrm{Ni}^{2+}$ in the compartment on the right has each of the following values.
a. $1.0 \mathrm{M}$
b. $2.0 \mathrm{M}$
c. $0.10 \mathrm{M}$
d. $4.0 \times 10^{-5} M$
e. Calculate the potential when both solutions are $2.5 M$ in $\mathrm{Ni}^{2+}$. For each case, also identify the cathode, anode, and the direction in which electrons flow.

David Collins
David Collins
Numerade Educator
01:49

Problem 67

The overall reaction in the lead storage battery is
$\mathrm{Pb}(s)+\mathrm{PbO}_{2}(s)+2 \mathrm{H}^{+}(a q)+2 \mathrm{HSO}_{4}^{-}(a q) \longrightarrow$
Calculate $\mathscr{8}$ at $25^{\circ} \mathrm{C}$ for this battery when $\left[\mathrm{H}_{2} \mathrm{SO}_{4}\right]=4.5 M$, that is, $\left[\mathrm{H}^{+}\right]=\left[\mathrm{HSO}_{4}^{-}\right]=4.5 M .$ At $25^{\circ} \mathrm{C}, \mathscr{b}^{\circ}=2.04 \mathrm{~V}$ for the lead
storage battery.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:49

Problem 68

Calculate the $\mathrm{pH}$ of the cathode compartment for the following reaction given $\mathscr{E}_{\text {cell }}=3.01 \mathrm{~V}$ when $\left[\mathrm{Cr}^{3+}\right]=0.15 \mathrm{M},\left[\mathrm{Al}^{3+}\right]=$
$0.30 M$, and $\left[\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}\right]=0.55 M$
$2 \mathrm{Al}(s)+\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+14 \mathrm{H}^{+}(a q) \longrightarrow$
$2 \mathrm{Al}^{3+}(a q)+2 \mathrm{Cr}^{3+}(a q)+7 \mathrm{H}_{2} \mathrm{O}(l)$

David Collins
David Collins
Numerade Educator
00:48

Problem 69

Consider the cell described below:
$$\mathrm{Zn}\left|\mathrm{Zn}^{2+}(1.00 M) \| \mathrm{Cu}^{2+}(1.00 M)\right| \mathrm{Cu}$$
Calculate the cell potential after the reaction has operated long enough for the $\left[\mathrm{Zn}^{2+}\right]$ to have changed by $0.20 \mathrm{~mol} / \mathrm{L}$. (Assume $\left.T=25^{\circ} \mathrm{C} .\right)$

David Collins
David Collins
Numerade Educator
00:58

Problem 70

Consider the cell described below:
$$\mathrm{Al}\left|\mathrm{Al}^{3+}(1.00 M)\right|\left|\mathrm{Pb}^{2+}(1.00 M)\right| \mathrm{Pb}$$
Calculate the cell potential after the reaction has operated long enough for the $\left[\mathrm{Al}^{3+}\right]$ to have changed by $0.60 \mathrm{~mol} / \mathrm{L}$. (Assume $\left.T=25^{\circ} \mathrm{C} .\right)$

David Collins
David Collins
Numerade Educator
06:13

Problem 71

Calculate $\Delta G^{\circ}$ and $K$ at $25^{\circ} \mathrm{C}$ for the reactions in Exercises 35 and 39 .

David Collins
David Collins
Numerade Educator
06:58

Problem 72

Calculate $\Delta G^{\circ}$ and $K$ at $25^{\circ} \mathrm{C}$ for the reactions in Exercises 36 and 40 .

David Collins
David Collins
Numerade Educator
01:17

Problem 73

Consider the galvanic cell based on the following half-reactions:
$$\begin{array}{ll}\mathrm{Zn}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Zn} & \mathscr{E}^{\circ}=-0.76 \mathrm{~V} \\
\mathrm{Fe}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Fe} & \mathscr{E}^{\circ}=-0.44 \mathrm{~V}
\end{array}$$
a. Determine the overall cell reaction and calculate $\mathscr{E}_{\mathrm{cell}}^{\circ}$
b. Calculate $\Delta G^{\circ}$ and $K$ for the cell reaction at $25^{\circ} \mathrm{C}$.
c. Calculate $\mathscr{B}_{\text {coll }}$ at $25^{\circ} \mathrm{C}$ when $\left[\mathrm{Zn}^{2+}\right]=0.10 \mathrm{M}$ and $\left[\mathrm{Fe}^{2+}\right]=$ $1.0 \times 10^{-5} M$

David Collins
David Collins
Numerade Educator
View

Problem 74

Consider the galvanic cell based on the following half-reactions:
$$\begin{array}{ll}\mathrm{Au}^{3+}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Au} & \mathscr{E}^{\circ}=1.50 \mathrm{~V} \\
\mathrm{Tl}^{+}+\mathrm{e}^{-} \longrightarrow \mathrm{Tl} & \mathscr{E}^{\circ}=-0.34 \mathrm{~V}
\end{array}$$
a. Determine the overall cell reaction and calculate $\mathscr{E}_{\mathrm{ccll}}^{\circ}$
b. Calculate $\Delta G^{\circ}$ and $K$ for the cell reaction at $25^{\circ} \mathrm{C}$.
c. Calculate $\mathscr{E}_{\text {cell }}$ at $25^{\circ} \mathrm{C}$ when $\left[\mathrm{Au}^{3+}\right]=1.0 \times 10^{-2} M$ and $\left[\mathrm{Tl}^{+}\right]=1.0 \times 10^{-4} \mathrm{M}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:04

Problem 75

An electrochemical cell consists of a standard hydrogen electrode and a copper metal electrode.
a. What is the potential of the cell at $25^{\circ} \mathrm{C}$ if the copper electrode is placed in a solution in which $\left[\mathrm{Cu}^{2+}\right]=2.5 \times 10^{-4} M ?$
b. The copper electrode is placed in a solution of unknown $\left[\mathrm{Cu}^{2+}\right]$. The measured potential at $25^{\circ} \mathrm{C}$ is $0.195 \mathrm{~V}$. What is $\left[\mathrm{Cu}^{2+}\right] ?$ (Assume $\mathrm{Cu}^{2+}$ is reduced.)

David Collins
David Collins
Numerade Educator
02:56

Problem 76

An electrochemical cell consists of a nickel metal electrode immersed in a solution with $\left[\mathrm{Ni}^{2+}\right]=1.0 M$ separated by a porous disk from an aluminum metal electrode.
a. What is the potential of this cell at $25^{\circ} \mathrm{C}$ if the aluminum electrode is placed in a solution in which $\left[\mathrm{Al}^{3+}\right]=7.2 \times 10^{-3} M ?$
b. When the aluminum electrode is placed in a certain solution in which $\left[\mathrm{Al}^{3+}\right]$ is unknown, the measured cell potential at $25^{\circ} \mathrm{C}$ is $1.62 \mathrm{~V} .$ Calculate $\left[\mathrm{Al}^{3+}\right]$ in the unknown solution. (Assume Al is oxidized.)

Eric Ferrara
Eric Ferrara
Numerade Educator
View

Problem 77

An electrochemical cell consists of a standard hydrogen electrode and a copper metal electrode. If the copper electrode is placed in a solution of $0.10 \mathrm{M} \mathrm{NaOH}$ that is saturated with $\mathrm{Cu}(\mathrm{OH})_{2}$, what is the cell potential at $25^{\circ} \mathrm{C} ?\left[\right.$ For $\mathrm{Cu}(\mathrm{OH})_{2}, K_{\text {sp }}=1.6 \times 10^{-19}$ ]

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:46

Problem 78

An electrochemical cell consists of a nickel metal electrode immersed in a solution with $\left[\mathrm{Ni}^{2+}\right]=1.0 M$ separated by a porous disk from an aluminum metal electrode immersed in a solution with $\left[\mathrm{Al}^{3+}\right]=1.0 M .$ Sodium hydroxide is added to the aluminum compartment, causing $\mathrm{Al}(\mathrm{OH})_{3}(s)$ to precipitate. After precipitation of $\mathrm{Al}(\mathrm{OH})_{3}$ has ceased, the concentration of $\mathrm{OH}^{-}$ is $1.0 \times 10^{-4} M$ and the measured cell potential is $1.82 \mathrm{~V}$. Calculate the $K_{\mathrm{sp}}$ value for $\mathrm{Al}(\mathrm{OH})_{3}$.
$$\mathrm{Al}(\mathrm{OH})_{3}(s) \rightleftharpoons \mathrm{Al}^{3+}(a q)+3 \mathrm{OH}^{-}(a q) \quad K_{\mathrm{sp}}=?$$

Eric Ferrara
Eric Ferrara
Numerade Educator
View

Problem 79

Consider a concentration cell that has both electrodes made of some metal M. Solution A in one compartment of the cell contains $1.0 \mathrm{M} \mathrm{M}^{2+}$. Solution $\mathrm{B}$ in the other cell compartment has a volume of $1.00 \mathrm{~L}$. At the beginning of the experiment $0.0100$ $\mathrm{mol} \mathrm{M}\left(\mathrm{NO}_{3}\right)_{2}$ and $0.0100 \mathrm{~mol} \mathrm{Na}_{2} \mathrm{SO}_{4}$ are dissolved in solution
$\mathrm{B}$ (ignore volume changes), where the reaction
$$\mathrm{M}^{2+}(a q)+\mathrm{SO}_{4}{ }^{2-}(a q) \rightleftharpoons \operatorname{MSO}_{4}(s)$$
occurs. For this reaction equilibrium is rapidly established, whereupon the cell potential is found to be $+0.44 \mathrm{~V}$ at $25^{\circ} \mathrm{C}$. Assume that the process
$$\mathrm{M}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{M}$$
has a standard reduction potential of $-0.31 \mathrm{~V}$ and that no other redox process occurs in the cell. Calculate the value of $K_{\mathrm{sp}}$ for. $\mathrm{MSO}_{4}(s)$ at $25^{\circ} \mathrm{C}$.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:25

Problem 80

You have a concentration cell in which the cathode has a silver electrode with $0.10 \mathrm{MAg}^{+}$. The anode also has a silver electrode with $\mathrm{Ag}^{+}(a q), 0.050 \mathrm{M} \mathrm{S}_{2} \mathrm{O}_{3}{ }^{2-}$, and $1.0 \times 10^{-3} \mathrm{M} \mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}{ }^{3-}$.
You read the voltage to be $0.76 \mathrm{~V}$.
a. Calculate the concentration of $\mathrm{Ag}^{+}$ at the anode.
b. Determine the value of the equilibrium constant for the formation of $\mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}{ }^{3-}$
$\mathrm{Ag}^{+}(a q)+2 \mathrm{~S}_{2} \mathrm{O}_{3}{ }^{2-}(a q) \rightleftharpoons \mathrm{Ag}\left(\mathrm{S}_{2} \mathrm{O}_{3}\right)_{2}{ }^{3-}(a q) \quad K=?$

David Collins
David Collins
Numerade Educator
01:26

Problem 81

Under standard conditions, what reaction occurs, if any, when each of the following operations is performed?
a. Crystals of $\mathrm{I}_{2}$ are added to a solution of $\mathrm{NaCl}$.
b. $\mathrm{Cl}_{2}$ gas is bubbled into a solution of NaI.
c. A silver wire is placed in a solution of $\mathrm{CuCl}_{2}$.
d. An acidic solution of $\mathrm{FeSO}_{4}$ is exposed to air. For the reactions that occur, write a balanced equation and calculate $\mathscr{E}^{\circ}, \Delta G^{\circ}$, and $K$ at $25^{\circ} \mathrm{C}$.

David Collins
David Collins
Numerade Educator
View

Problem 82

A disproportionation reaction involves a substance that acts as both an oxidizing and a reducing agent, producing higher and lower oxidation states of the same element in the products. Which of the following disproportionation reactions are spontaneous under standard conditions? Calculate $\Delta G^{\circ}$ and $K$ at $25^{\circ} \mathrm{C}$ for those reactions that are spontaneous under standard conditions.
a. $2 \mathrm{Cu}^{+}(a q) \rightarrow \mathrm{Cu}^{2+}(a q)+\mathrm{Cu}(s)$
b. $3 \mathrm{Fe}^{2+}(a q) \rightarrow 2 \mathrm{Fe}^{3+}(a q)+\mathrm{Fe}(s)$
c. $\mathrm{HClO}_{2}(a q) \rightarrow \mathrm{ClO}_{3}^{-}(a q)+\mathrm{HClO}(a q) \quad$ (unbalanced)
Use the half-reactions:
$\mathrm{ClO}_{3}^{-}+3 \mathrm{H}^{+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{HClO}_{2}+\mathrm{H}_{2} \mathrm{O} \quad \mathscr{E}^{\circ}=1.21 \mathrm{~V}$
$\mathrm{HClO}_{2}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{HClO}+\mathrm{H}_{2} \mathrm{O} \quad \mathscr{E}^{\circ}=1.65 \mathrm{~V}$

David Collins
David Collins
Numerade Educator
01:32

Problem 83

Consider the following galvanic cell at $25^{\circ} \mathrm{C}$ :
$$\mathrm{Pt}\left|\mathrm{Cr}^{2+}(0.30 M), \mathrm{Cr}^{3+}(2.0 M)\right|\left|\mathrm{Co}^{2+}(0.20 M)\right| \mathrm{Co}$$
The overall reaction and equilibrium constant value are
$$2 \mathrm{Cr}^{2+}(a q)+\mathrm{Co}^{2+}(a q) \longrightarrow{2 \mathrm{Cr}^{3+}(a q)+\mathrm{Co}(s)} \quad K=2.79 \times 10^{7}$$
Calculate the cell potential, $\mathscr{E}$, for this galvanic cell and $\Delta G$ for the cell reaction at these conditions.

David Collins
David Collins
Numerade Educator
01:26

Problem 84

An electrochemical cell consists of a silver metal electrode im. mersed in a solution with $\left[\mathrm{Ag}^{+}\right]=1.0 M$ separated by a porous disk from a copper metal electrode. If the copper electrode is placed in a solution of $5.0 \mathrm{M} \mathrm{NH}_{3}$ that is also $0.010 \mathrm{M}$ in $\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}^{2+}$, what is the cell potential at $25^{\circ} \mathrm{C} ?$
$$\begin{aligned}\mathrm{Cu}^{2+}(a q)+4 \mathrm{NH}_{3}(a q) \rightleftharpoons \mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}{ }^{2+}(a q) & K=1.0 \times 10^{13}\end{aligned}$$

David Collins
David Collins
Numerade Educator
01:23

Problem 85

Calculate $K_{\mathrm{sp}}$ for iron(II) sulfide given the following data:
$$\begin{aligned}\mathrm{FeS}(s)+2 \mathrm{e}^{-} \longrightarrow \mathrm{Fe}(s)+\mathrm{S}^{2-}(a q) & & \mathscr{b}^{\circ} &=-1.01 \mathrm{~V} \\\mathrm{Fe}^{2+}(a q)+2 \mathrm{e}^{-} \longrightarrow \mathrm{Fe}(s) & & \mathscr{b}^{\circ} &=-0.44 \mathrm{~V}
\end{aligned}$$

David Collins
David Collins
Numerade Educator
03:50

Problem 86

For the following half-reaction, $\mathscr{E}^{\circ}=-2.07 \mathrm{~V}$ :
$$\mathrm{AlF}_{6}^{3-}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Al}+6 \mathrm{~F}^{-}$$
Using data from Table $18.1$, calculate the equilibrium constant at $25^{\circ} \mathrm{C}$ for the reaction
$$\mathrm{Al}^{3+}(a q)+6 \mathrm{~F}^{-}(a q) \rightleftharpoons \mathrm{AlF}_{6}^{3-}(a q) \quad K=?$$

Eric Ferrara
Eric Ferrara
Numerade Educator
03:07

Problem 87

Calculate $\mathscr{E}^{\circ}$ for the following half-reaction:
$$\operatorname{AgI}(s)+\mathrm{e}^{-} \longrightarrow \mathrm{Ag}(s)+\mathrm{I}^{-}$$

David Collins
David Collins
Numerade Educator
04:11

Problem 88

The solubility product for $\operatorname{Cul}(s)$ is $1.1 \times 10^{-12}$. Calculate the value of $\mathscr{E}^{\circ}$ for the half-reaction
$$\mathrm{CuI}+\mathrm{e}^{-} \longrightarrow \mathrm{Cu}+\mathrm{I}^{-}$$

Shalini Tyagi
Shalini Tyagi
Numerade Educator
10:54

Problem 89

How long will it take to plate out each of the following with a current of $100.0 \mathrm{~A}$ ?
a. $1.0 \mathrm{~kg} \mathrm{Al}$ from aqueous $\mathrm{Al}^{3+}$
b. $1.0 \mathrm{~g} \mathrm{Ni}$ from aqueous $\mathrm{Ni}^{2+}$
c. $5.0 \mathrm{~mol} \mathrm{Ag}$ from aqueous $\mathrm{Ag}^{+}$

Shalini Tyagi
Shalini Tyagi
Numerade Educator
02:57

Problem 90

The electrolysis of $\mathrm{BiO}^{+}$ produces pure bismuth. How long would it take to produce $10.0 \mathrm{~g} \mathrm{Bi}$ by the electrolysis of a $\mathrm{BiO}^{+}$ solution using a current of $25.0 \mathrm{~A}$ ?

Eric Ferrara
Eric Ferrara
Numerade Educator
14:17

Problem 91

What mass of each of the following substances can be produced in $1.0 \mathrm{~h}$ with a current of $15 \mathrm{~A}$ ?
a. Co from aqueous $\mathrm{Co}^{2+}$
b. Hf from aqueous $\mathrm{Hf}^{4+}$
c. $\mathrm{I}_{2}$ from aqueous $\mathrm{KI}$
d. Cr from molten $\mathrm{CrO}_{3}$

Julia G.
Julia G.
Numerade Educator
00:39

Problem 92

Aluminum is produced commercially by the electrolysis of $\mathrm{Al}_{2} \mathrm{O}_{3}$ in the presence of a molten salt. If a plant has a continuous capacity of $1.00$ million A, what mass of aluminum can be produced in $2.00 \mathrm{~h} ?$

David Collins
David Collins
Numerade Educator
00:49

Problem 93

An unknown metal $\mathrm{M}$ is electrolyzed. It took $74.1 \mathrm{~s}$ for a current of $2.00 \mathrm{~A}$ to plate out $0.107 \mathrm{~g}$ of the metal from a solution containing $\mathrm{M}\left(\mathrm{NO}_{3}\right)_{3}$. Identify the metal.

David Collins
David Collins
Numerade Educator
00:52

Problem 94

Electrolysis of an alkaline earth metal chloride using a current of $5.00 \mathrm{~A}$ for $748 \mathrm{~s}$ deposits $0.471 \mathrm{~g}$ of metal at the cathode. What is the identity of the alkaline earth metal chloride?

David Collins
David Collins
Numerade Educator
01:06

Problem 95

What volume of $\mathrm{F}_{2}$ gas, at $25^{\circ} \mathrm{C}$ and $1.00 \mathrm{~atm}$, is produced when molten $\mathrm{KF}$ is electrolyzed by a current of $10.0 \mathrm{~A}$ for $2.00 \mathrm{~h} ?$ What mass of potassium metal is produced? At which electrode does each reaction occur?

David Collins
David Collins
Numerade Educator
00:57

Problem 96

What volumes of $\mathrm{H}_{2}(g)$ and $\mathrm{O}_{2}(g)$ at STP are produced from the electrolysis of water by a current of $2.50 \mathrm{~A}$ in $15.0 \mathrm{~min} ?$

David Collins
David Collins
Numerade Educator
02:12

Problem 97

A single Hall-Heroult cell (as shown in Fig. $18.22$ ) produces about 1 ton of aluminum in $24 \mathrm{~h}$. What current must be used to accomplish this?

Bhumika Jayee
Bhumika Jayee
Numerade Educator
00:42

Problem 98

A factory wants to produce $1.00 \times 10^{3} \mathrm{~kg}$ barium from the electrolysis of molten barium chloride. What current must be applied for $4.00 \mathrm{~h}$ to accomplish this?

David Collins
David Collins
Numerade Educator
00:32

Problem 99

It took $2.30$ min using a current of $2.00$ A to plate out all the silver from $0.250 \mathrm{~L}$ of a solution containing $\mathrm{Ag}^{+}$. What was the original concentration of $\mathrm{Ag}^{+}$ in the solution?

David Collins
David Collins
Numerade Educator
00:27

Problem 100

A solution containing $\mathrm{Pt}^{4+}$ is electrolyzed with a current of $4.00 \mathrm{~A}$. How long will it take to plate out $99 \%$ of the platinum in $0.50 \mathrm{~L}$ of a $0.010 \mathrm{M}$ solution of $\mathrm{Pt}^{4+}$ ?

David Collins
David Collins
Numerade Educator
00:39

Problem 101

A solution at $25^{\circ} \mathrm{C}$ contains $1.0 \mathrm{M} \mathrm{Cd}^{2+}, 1.0 \mathrm{MAg}^{+}, 1.0 \mathrm{M} \mathrm{Au}^{3+}$,
and $1.0 \mathrm{M} \mathrm{Ni}^{2+}$ in the cathode compartment of an electrolytic cell. Predict the order in which the metals will plate out as the voltage is gradually increased.

David Collins
David Collins
Numerade Educator
04:50

Problem 102

Consider the following half-reactions:
$$\begin{array}{cc}\mathrm{IrCl}_{6}{ }^{3-}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Ir}+6 \mathrm{Cl}^{-} & \mathscr{E}^{\circ}=0.77 \mathrm{~V} \\
\mathrm{PtCl}_{4}{ }^{2-}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pt}+4 \mathrm{Cl}^{-} & \mathscr{E}^{\circ}=0.73 \mathrm{~V} \\
\mathrm{PdCl}_{4}{ }^{2-}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pd}+4 \mathrm{Cl}^{-} & \mathscr{E}^{\circ}=0.62 \mathrm{~V}
\end{array}$$
A hydrochloric acid solution contains platinum, palladium, and iridium as chloro-complex ions. The solution is a constant $1.0 \mathrm{M}$ in chloride ion and $0.020 \mathrm{M}$ in each complex ion. Is it feasible to separate the three metals from this solution by electrolysis? (Assume that $99 \%$ of a metal must be plated out before another metal begins to plate out.)

David Collins
David Collins
Numerade Educator
00:22

Problem 103

What reactions take place at the cathode and the anode when each of the following is electrolyzed?
a. molten $\mathrm{NiBr}_{2}$
b. molten $\mathrm{AlF}_{3}$
c. molten $\mathrm{MnI}_{2}$

David Collins
David Collins
Numerade Educator
01:58

Problem 104

What reaction will take place at the cathode and the anode when each of the following is electrolyzed?
a. molten $\mathrm{KF}$
b. molten $\mathrm{CuCl}_{2}$
c. molten $\mathrm{MgI}_{2}$

Eric Ferrara
Eric Ferrara
Numerade Educator
13:30

Problem 105

What reactions take place at the cathode and the anode when each of the following is electrolyzed? (Assume standard conditions.)
a. $1.0 M \mathrm{NiBr}_{2}$ solution
b. $1.0 \mathrm{M} \mathrm{AlF}_{3}$ solution
c. $1.0 \mathrm{M} \mathrm{MnI}_{2}$ solution

Shalini Tyagi
Shalini Tyagi
Numerade Educator
03:18

Problem 106

What reaction will take place at the cathode and the anode when each of the following is electrolyzed? (Assume standard conditions.)
a. $1.0 \mathrm{M}$ KF solution
b. $1.0 \mathrm{M} \mathrm{CuCl}_{2}$ solution
c. $1.0 \mathrm{M} \mathrm{MgI}_{2}$ solution

David Collins
David Collins
Numerade Educator
00:52

Problem 107

The blood alcohol $\left(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}\right)$ level can be determined by titrating a sample of blood plasma with an acidic potassium dichromate solution, resulting in the production of $\mathrm{Cr}^{3+}(a q)$ and carbon dioxide. The reaction can be monitored because the dichromate ion $\left(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}\right)$ is orange in solution, and the $\mathrm{Cr}^{3+}$ ion is green. The unbalanced redox equation is
$$\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}(a q)+\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(a q) \longrightarrow \mathrm{Cr}^{3+}(a q)+\mathrm{CO}_{2}(g)$$
If $31.05 \mathrm{~mL}$ of $0.0600 M$ potassium dichromate solution is required to titrate $30.0 \mathrm{~g}$ blood plasma, determine the mass percent of alcohol in the blood.

David Collins
David Collins
Numerade Educator
03:59

Problem 108

Direct methanol fuel cells (DMFCs) have shown some promise as a viable option for providing "green" energy to small electrical devices. Calculate $\mathscr{\ell}^{\circ}$ for the reaction that takes place in DMFCs:
$$\mathrm{CH}_{3} \mathrm{OH}(l)+3 / 2 \mathrm{O}_{2}(g) \longrightarrow \mathrm{CO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(l)$$
Use values of $\Delta G_{\mathrm{f}}^{\circ}$ from Appendix 4 .

Ronald Prasad
Ronald Prasad
Numerade Educator
04:13

Problem 109

A fuel cell designed to react grain alcohol with oxygen has the following net reaction:
$$\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(I)+3 \mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{CO}_{2}(g)+3 \mathrm{H}_{2} \mathrm{O}(l)$$
The maximum work that 1 mole of alcohol can do is $1.32 \times$ $10^{3} \mathrm{~kJ} .$ What is the theoretical maximum voltage this cell can achieve at $25^{\circ} \mathrm{C} ?$

Ronald Prasad
Ronald Prasad
Numerade Educator
04:05

Problem 110

Nerve impulses are electrical "signals" that pass through neurons in the body. The electrical potential is created by the differences in the concentration of $\mathrm{Na}^{+}$ and $\mathrm{K}^{+}$ ions across the nerve cell membrane. We can think about this potential as being caused by a concentration gradient, similar to what we see in a concentration cell (keep in mind that this is a very simple explanation of how nerves work; there is much more involved in the true biologic process). A typical nerve cell has a resting potential of about $-70 \mathrm{mV}$. Let's assume that this resting potential is due only to the $\mathrm{K}^{+}$ ion concentration difference. In nerve cells, the $\mathrm{K}^{+}$ concentration inside the cell is larger than the $\mathrm{K}^{+}$ concentration outside the cell. Calculate the $\mathrm{K}^{+}$ ion concentration ratio necessary to produce a resting potential of $-70 . \mathrm{mV}$.
$$\frac{\left[\mathrm{K}^{+}\right]_{\text {inside }}}{\left[\mathrm{K}^{+}\right]_{\text {outside }}}=?$$

Bryan Valdivia
Bryan Valdivia
Numerade Educator
06:33

Problem 111

Glucose is the major fuel for most living cells. The oxidative breakdown of glucose by our body to produce energy is called respiration. The reaction for the complete combustion of glucose is
$$\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}(s)+6 \mathrm{O}_{2}(g) \longrightarrow 6 \mathrm{CO}_{2}(g)+6 \mathrm{H}_{2} \mathrm{O}(l)$$
If this combustion reaction could be harnessed as a fuel cell, calculate the theoretical voltage that could be produced at standard conditions.

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
01:08

Problem 112

The ultimate electron acceptor in the respiration process is molecular oxygen. Electron transfer through the respiratory chain takes place through a complex series of oxidation-reduction reactions. Some of the electron transport steps use iron-containing proteins called cytochromes. All cytochromes transport electrons by converting the iron in the cytochromes from the $+3$ to the $+2$ oxidation state. Consider the following reduction potentials for three different cytochromes used in the transfer process of electrons to oxygen (the potentials have been corrected for $\mathrm{pH}$ and for temperature):
$\begin{aligned} \text { cytochrome } \mathrm{a}\left(\mathrm{Fe}^{3+}\right)+\mathrm{e}^{-} \longrightarrow \text { cytochrome } \mathrm{a}\left(\mathrm{Fe}^{2+}\right) & \\ \mathscr{B} &=0.385 \mathrm{~V} \\ \text { cytochrome } \mathrm{b}\left(\mathrm{Fe}^{3+}\right)+\mathrm{e}^{-} \longrightarrow \text { cytochrome } \mathrm{b}\left(\mathrm{Fe}^{2+}\right) & \\ \mathscr{E} &=0.030 \mathrm{~V} \\ \text { cytochrome } \mathrm{c}\left(\mathrm{Fe}^{3+}\right)+\mathrm{e}^{-} \longrightarrow \text { cytochrome } \mathrm{c}\left(\mathrm{Fe}^{2+}\right) & \\ \mathscr{Z} &=0.254 \mathrm{~V} \end{aligned}$
In the electron transfer series, electrons are transferred from one cytochrome to another. Using this information, determine the cytochrome order necessary for spontaneous transport of electrons from one cytochrome to another, which eventually will lead to electron transfer to $\mathrm{O}_{2}$.

David Collins
David Collins
Numerade Educator
02:58

Problem 113

One of the few industrial-scale processes that produce organic compounds electrochemically is used by the Monsanto Company to produce 1,4 -dicyanobutane. The reduction reaction is
$$2 \mathrm{CH}_{2}=\mathrm{CHCN}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{NC}-\left(\mathrm{CH}_{2}\right)_{4}-\mathrm{CN}$$
The $\mathrm{NC}-\left(\mathrm{CH}_{2}\right)_{4}-\mathrm{CN}$ is then chemically reduced using hydrogen gas to $\mathrm{H}_{2} \mathrm{~N}-\left(\mathrm{CH}_{2}\right)_{6}-\mathrm{NH}_{2}$, which is used in the production of nylon. What current must be used to produce $150 . \mathrm{kg}$ $\mathrm{NC}-\left(\mathrm{CH}_{2}\right)_{4}-\mathrm{CN}$ per hour?

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
01:52

Problem 114

Mercury is a toxic substance, and specifically hazardous when it is present in the $+1$ or $+2$ oxidation states. However, the American Dental Association has determined that dental fillings composed of elemental mercury pose minimal health risks, even if the filling is swallowed. Use Table $18.1$ to propose a possible explanation for this apparent contradiction.

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
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Problem 115

The saturated calomel electrode, abbreviated SCE, is often used as a reference electrode in making electrochemical measurements. The SCE is composed of mercury in contact with a saturated solution of calomel $\left(\mathrm{Hg}_{2} \mathrm{Cl}_{2}\right) .$ The electrolyte solution is saturated KCl. $\mathscr{C}_{\mathrm{SCE}}$ is $+0.242 \mathrm{~V}$ relative to the standard hydrogen electrode. Calculate the potential for each of the following galvanic cells containing a saturated calomel electrode and the given half-cell components at standard conditions. In each case, indicate whether the SCE is the cathode or the anode. Standard reduction potentials are found in Table $18.1$.
a. $\mathrm{Cu}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Cu}$
d. $\mathrm{Al}^{3+}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Al}$
b. $\mathrm{Fe}^{3+}+\mathrm{e}^{-} \longrightarrow \mathrm{Fe}^{2+}$
e. $\mathrm{Ni}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Ni}$
c. $\mathrm{AgCl}+\mathrm{e}^{-} \longrightarrow \mathrm{Ag}+\mathrm{Cl}^{-}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:33

Problem 116

Consider the following half-reactions:
$$\begin{aligned}\mathrm{Pt}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pt} & & \mathscr{E}^{\circ}=1.188 \mathrm{~V} \\
\mathrm{PtCl}_{4}^{2-}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pt}+4 \mathrm{Cl}^{-} & & \mathscr{C}^{\circ}=0.755 \mathrm{~V} \\
\mathrm{NO}_{3}^{-}+4 \mathrm{H}^{+}+3 \mathrm{e}^{-} \longrightarrow \mathrm{NO}+2 \mathrm{H}_{2} \mathrm{O} & & \mathscr{C}^{\circ}=0.96 \mathrm{~V}\end{aligned}$$
Explain why platinum metal will dissolve in aqua regia (a mixture of hydrochloric and nitric acids) but not in either concentrated nitric or concentrated hydrochloric acid individually.

Eric Ferrara
Eric Ferrara
Numerade Educator
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Problem 117

Consider the standard galvanic cell based on the following halfreactions:
$$\begin{array}{r}\mathrm{Cu}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Cu} \\
\mathrm{Ag}^{+}+\mathrm{e}^{-} \longrightarrow \mathrm{Ag}\end{array}$$
The electrodes in this cell are $\mathrm{Ag}(s)$ and $\mathrm{Cu}(s)$. Does the cell potential increase, decrease, or remain the same when the following changes occur to the standard cell?
a. $\operatorname{CuSO}_{4}(s)$ is added to the copper half-cell compartment (assume no volume change).
b. $\mathrm{NH}_{3}(a q)$ is added to the copper half-cell compartment. [Hint:
$\mathrm{Cu}^{2+}$ reacts with $\mathrm{NH}_{3}$ to form $\left.\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}^{2+}(a q) .\right]$
c. $\mathrm{NaCl}(s)$ is added to the silver half-cell compartment. [Hint:
$\mathrm{Ag}^{+}$ reacts with $\mathrm{Cl}^{-}$ to form $\left.\mathrm{AgCl}(s) .\right]$
d. Water is added to both half-cell compartments until the volume of solution is doubled.
e. The silver electrode is replaced with a platinum electrode.
$$\mathrm{Pt}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Pt} \quad \mathscr{E}^{\circ}=1.19 \mathrm{~V}$$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:11

Problem 118

A standard galvanic cell is constructed so that the overall cell reaction is
$$2 \mathrm{Al}^{3+}(a q)+3 \mathrm{M}(s) \longrightarrow 3 \mathrm{M}^{2+}(a q)+2 \mathrm{Al}(s)$$
where $\mathrm{M}$ is an unknown metal. If $\Delta G^{\circ}=-411 \mathrm{~kJ}$ for the overall cell reaction, identify the metal used to construct the standard cell.

David Collins
David Collins
Numerade Educator
01:30

Problem 119

The black silver sulfide discoloration of silverware can be removed by heating the silver article in a sodium carbonate solution in an aluminum pan. The reaction is
$$3 \mathrm{Ag}_{2} \mathrm{~S}(s)+2 \mathrm{Al}(s) \rightleftharpoons 6 \mathrm{Ag}(s)+3 \mathrm{~S}^{2-}(a q)+2 \mathrm{Al}^{3+}(a q)$$
a. Using data in Appendix 4 , calculate $\Delta G^{\circ}, K$, and $\mathscr{C}^{\circ}$ for the above reaction at $25^{\circ} \mathrm{C}$. (For $\mathrm{Al}^{3+}(a q), \Delta G_{\mathrm{f}}^{\circ}=-480 . \mathrm{kJ} / \mathrm{mol}$.)
b. Calculate the value of the standard reduction potential for the following half-reaction:
$$2 \mathrm{e}^{-}+\mathrm{Ag}_{2} \mathrm{~S}(s) \longrightarrow 2 \mathrm{Ag}(s)+\mathrm{S}^{2-}(a q)$$

David Collins
David Collins
Numerade Educator
00:43

Problem 120

In 1973 the wreckage of the Civil War ironclad USS Monitor was discovered near Cape Hatteras, North Carolina. [The Monitor and the CSS Virginia (formerly the USS Merrimack) fought the first battle between iron-armored ships.] In 1987 investigations were begun to see if the ship could be salvaged. It was reported in Time (June 22,1987 ) that scientists were considering adding sacrificial anodes of zinc to the rapidly corroding metal hull of the Monitor. Describe how attaching zinc to the hull would protect the Monitor from further corrosion.

David Collins
David Collins
Numerade Educator
02:25

Problem 121

When aluminum foil is placed in hydrochloric acid, nothing happens for the first 30 seconds or so. This is followed by vigorous bubbling and the eventual disappearance of the foil. Explain these observations.

Jennifer Hudspeth
Jennifer Hudspeth
Numerade Educator
02:03

Problem 122

Which of the following statements concerning corrosion is/are true? For the false statements, correct them.
a. Corrosion is an example of an electrolytic process.
b. Corrosion of steel involves the reduction of iron coupled with the oxidation of oxygen.
c. Steel rusts more easily in the dry (arid) Southwest states than in the humid Midwest states.
d. Salting roads in the winter has the added benefit of hindering the corrosion of steel.
e. The key to cathodic protection is to connect via a wire a metal more easily oxidized than iron to the steel surface to be protected.

David Collins
David Collins
Numerade Educator
01:35

Problem 123

A patent attorney has asked for your advice concerning the merits of a patent application that describes a single aqueous galvanic cell capable of producing a 12-V potential. Comment.

David Collins
David Collins
Numerade Educator
01:35

Problem 124

The overall reaction and equilibrium constant value for a hydrogen-oxygen fuel cell at $298 \mathrm{~K}$ is
$$2 \mathrm{H}_{2}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{H}_{2} \mathrm{O}(I) \quad K=1.28 \times 10^{83}$$
a. Calculate $\mathscr{C}^{\circ}$ and $\Delta G^{\circ}$ at $298 \mathrm{~K}$ for the fuel cell reaction.
b. Predict the signs of $\Delta H^{\circ}$ and $\Delta S^{\circ}$ for the fuel cell reaction.
c. As temperature increases, does the maximum amount of work obtained from the fuel cell reaction increase, decrease, or remain the same? Explain.

David Collins
David Collins
Numerade Educator
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Problem 125

What is the maximum work that can be obtained from a hydrogen-oxygen fuel cell at standard conditions that produces $1.00 \mathrm{~kg}$ water at $25^{\circ} \mathrm{C} ?$ Why do we say that this is the maximum work that can be obtained? What are the advantages and disadvantages in using fuel cells rather than the corresponding combustion reactions to produce electricity?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:21

Problem 126

The overall reaction and standard cell potential at $25^{\circ} \mathrm{C}$ for the rechargeable nickel-cadmium alkaline battery is
$\mathrm{Cd}(s)+\mathrm{NiO}_{2}(s)+2 \mathrm{H}_{2} \mathrm{O}(l) \longrightarrow$
$\mathrm{Ni}(\mathrm{OH})_{2}(s)+\mathrm{Cd}(\mathrm{OH})_{2}(s) \quad \mathscr{E}^{\circ}=1.10 \mathrm{~V}$
For every mole of Cd consumed in the cell, what is the maximum useful work that can be obtained at standard conditions?

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
02:18

Problem 127

An experimental fuel cell has been designed that uses carbon monoxide as fuel. The overall reaction is
$$2 \mathrm{CO}(g)+\mathrm{O}_{2}(g) \longrightarrow 2 \mathrm{CO}_{2}(g)$$
The two half-cell reactions are
$$\begin{array}{l}\mathrm{CO}+\mathrm{O}^{2-} \longrightarrow \mathrm{CO}_{2}+2 \mathrm{e}^{-} \\\mathrm{O}_{2}+4 \mathrm{e}^{-} \longrightarrow 2 \mathrm{O}^{2-}
\end{array}$$
The two half-reactions are carried out in separate compartments connected with a solid mixture of $\mathrm{CeO}_{2}$ and $\mathrm{Gd}_{2} \mathrm{O}_{3} .$ Oxide ions can move through this solid at high temperatures (about $800^{\circ} \mathrm{C}$ ). $\Delta G$ for the overall reaction at $800^{\circ} \mathrm{C}$ under certain concentration conditions is $-380 \mathrm{~kJ} .$ Calculate the cell potential for this fuel cell at the same temperature and concentration conditions.

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
00:51

Problem 128

It took $150 . \mathrm{s}$ for a current of $1.25 \mathrm{~A}$ to plate out $0.109 \mathrm{~g}$ of $\mathrm{a}$ metal from a solution containing its cations. Show that it is not possible for the cations to have a charge of $1+$.

David Collins
David Collins
Numerade Educator
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Problem 129

Gold is produced electrochemically from an aqueous solution of $\mathrm{Au}(\mathrm{CN})_{2}^{-}$ containing an excess of $\mathrm{CN}^{-}$. Gold metal and oxygen gas are produced at the electrodes. What amount (moles) of $\mathrm{O}_{2}$ will be produced during the production of $1.00 \mathrm{~mol}$ gold?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:01

Problem 130

In the electrolysis of a sodium chloride solution, what volume of $\mathrm{H}_{2}(g)$ is produced in the same time it takes to produce $257 \mathrm{~L}$ $\mathrm{Cl}_{2}(\mathrm{~g})$, with both volumes measured at $50 .{ }^{\circ} \mathrm{C}$ and $2.50 \mathrm{~atm} ?$

David Collins
David Collins
Numerade Educator
00:41

Problem 131

An aqueous solution of an unknown salt of ruthenium is electrolyzed by a current of $2.50$ A passing for $50.0 \mathrm{~min}$. If $2.618 \mathrm{~g}$ Ru is produced at the cathode, what is the charge on the ruthenium ions in solution?

David Collins
David Collins
Numerade Educator
03:29

Problem 132

It takes $15 \mathrm{kWh}$ (kilowatt-hours) of electrical energy to produce 1.0 kg aluminum metal from aluminum oxide by the HallHeroult process. Compare this to the amount of energy necessary to melt $1.0 \mathrm{~kg}$ aluminum metal. Why is it economically feasible to recycle aluminum cans?

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
00:50

Problem 133

a. In the electrolysis of an aqueous solution of $\mathrm{Na}_{2} \mathrm{SO}_{4}$, what reactions occur at the anode and the cathode (assuming standard conditions)?
b. When water containing a small amount $(-0.01 M)$ of sodium sulfate is electrolyzed, measurement of the volume of gases generated consistently gives a result that the volume ratio of hydrogen to oxygen is not quite $2: 1 .$ To what do you attribute this discrepancy? Predict whether the measured ratio is greater than or less than $2: 1 .$ (Hint: Consider overvoltage.)

David Collins
David Collins
Numerade Educator
01:26

Problem 134

Balance the following equations by the half-reaction method.
a. $\mathrm{Fe}(s)+\mathrm{HCl}(a q) \longrightarrow \mathrm{HFeCl}_{4}(a q)+\mathrm{H}_{2}(g)$
b. $\mathrm{IO}_{3}^{-}(a q)+\mathrm{I}^{-}(a q) \stackrel{\text { Acid }}{\longrightarrow} \mathbf{I}_{3}^{-}(a q)$
c. $\begin{aligned} \mathrm{Cr}(\mathrm{NCS})_{6}^{4-}(a q)+\mathrm{Ce}^{4+}(a q) \stackrel{\mathrm{Acid}}{\longrightarrow} \\ & \mathrm{Cr}^{3+}(a q)+\mathrm{Ce}^{3+}(a q)+\mathrm{NO}_{3}^{-}(a q)+\mathrm{CO}_{2}(g)+\mathrm{SO}_{4}^{2-}(a q) \\ \text { d. } \mathrm{CrI}_{3}(s)+\mathrm{Cl}_{2}(g) \stackrel{\text { Base }}{\longrightarrow} \mathrm{CrO}_{4}^{2-}(a q)+\mathrm{IO}_{4}^{-}(a q)+\mathrm{Cl}^{-}(a q) \\ \text { e. } \mathrm{Fe}(\mathrm{CN})_{6}^{4-}(a q)+\mathrm{Ce}^{4+}(a q) \stackrel{\text { Base }}{\longrightarrow} \\ \mathrm{Ce}(\mathrm{OH})_{3}(s)+\mathrm{Fe}(\mathrm{OH})_{3}(s)+\mathrm{CO}_{3}^{2-}(a q)+\mathrm{NO}_{3}^{-}(a q) \end{aligned}$

Anand Jangid
Anand Jangid
Numerade Educator
07:04

Problem 135

Combine the equations
$$\Delta G^{\circ}=-n F \mathscr{\zeta}^{\circ} \text { and } \Delta G^{\circ}=\Delta H^{\circ}-T \Delta S^{\circ}$$
to derive an expression for $8^{\circ}$ as a function of temperature. Describe how one can graphically determine $\Delta H^{\circ}$ and $\Delta S^{\circ}$ from measurements of $\mathscr{E}^{\circ}$ at different temperatures, assuming that $\Delta H^{\circ}$ and $\Delta S^{\circ}$ do not depend on temperature. What property would you look for in designing a reference half-cell that would produce a potential relatively stable with respect to temperature?

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
01:10

Problem 136

The overall reaction in the lead storage battery is
$\mathrm{Pb}(s)+\mathrm{PbO}_{2}(s)+2 \mathrm{H}^{+}(a q)+2 \mathrm{HSO}_{4}^{-}(a q) \longrightarrow$
$2 \mathrm{PbSO}_{4}(s)+2 \mathrm{H}_{2} \mathrm{O}(l)$
a. For the cell reaction $\Delta H^{\circ}=-315.9 \mathrm{~kJ}$ and $\Delta S^{\circ}=263.5 \mathrm{~J} / \mathrm{K}$.
Calculate $\mathscr{}^{\circ}$ at $-20 .{ }^{\circ} \mathrm{C}$. Assume $\Delta H^{\circ}$ and $\Delta S^{\circ}$ do not depend on temperature.
b. Calculate 8 at $-20 .^{\circ} \mathrm{C}$ when $\left[\mathrm{HSO}_{4}^{-}\right]=\left[\mathrm{H}^{+}\right]=4.5 M$.
c. Consider your answer to Exercise $67 .$ Why does it seem that batteries fail more often on cold days than on warm days?

David Collins
David Collins
Numerade Educator
01:19

Problem 137

Consider the following galvanic cell: Calculate the $K_{\text {sp }}$ value for $\mathrm{Ag}_{2} \mathrm{SO}_{4}(s)$. Note that to obtain silver ions in the right compartment (the cathode compartment), excess solid $\mathrm{Ag}_{2} \mathrm{SO}_{4}$ was added and some of the salt dissolved.

David Collins
David Collins
Numerade Educator
09:55

Problem 138

A zinc-copper battery is constructed as follows at $25^{\circ} \mathrm{C}:$
$$\mathrm{Zn}\left|\mathrm{Zn}^{2+}(0.10 \mathrm{M}) \| \mathrm{Cu}^{2+}(2.50 \mathrm{M})\right| \mathrm{Cu}$$
The mass of each electrode is $200 . \mathrm{g}$.
a. Calculate the cell potential when this battery is first connected.
b. Calculate the cell potential after $10.0 \mathrm{~A}$ of current has flowed for $10.0 \mathrm{~h}$. (Assume each half-cell contains $1.00 \mathrm{~L}$ of solution.)
c. Calculate the mass of each electrode after $10.0 \mathrm{~h}$.
d. How long can this battery deliver a current of $10.0 \mathrm{~A}$ before it goes dead?

Bhumika Jayee
Bhumika Jayee
Numerade Educator
06:55

Problem 139

A galvanic cell is based on the following half-reactions:
$$\begin{array}{ll}\mathrm{Fe}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Fe}(s) & \mathscr{E}^{\circ}=-0.440 \mathrm{~V} \\
2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{H}_{2}(g) & \mathscr{E}^{\circ}=0.000 \mathrm{~V}
\end{array}$$
where the iron compartment contains an iron electrode and $\left[\mathrm{Fe}^{2+}\right]=1.00 \times 10^{-3} M$ and the hydrogen compartment contains a platinum electrode, $P_{\mathrm{H}_{2}}=1.00 \mathrm{~atm}$, and a weak acid, $\mathrm{HA}$, at an initial concentration of $1.00 M .$ If the observed cell potential is $0.333 \mathrm{~V}$ at $25^{\circ} \mathrm{C}$, calculate the $K_{\mathrm{a}}$ value for the weak acid HA.

Kevin Zaborsky
Kevin Zaborsky
Numerade Educator
06:22

Problem 140

Consider a cell based on the following half-reactions:
$$\begin{aligned}\mathrm{Au}^{3+}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Au} & \mathscr{C}^{\circ}=1.50 \mathrm{~V} \\
\mathrm{Fe}^{3+}+\mathrm{e}^{-} \longrightarrow \mathrm{Fe}^{2+} & \mathscr{C}^{\circ}=0.77 \mathrm{~V}
\end{aligned}$$
a. Draw this cell under standard conditions, labeling the anode, the cathode, the direction of electron flow, and the concentrations, as appropriate.
b. When enough $\mathrm{NaCl}(s)$ is added to the compartment containing gold to make the $\left[\mathrm{Cl}^{-}\right]=0.10 M$, the cell potential is observed to be $0.31 \mathrm{~V}$. Assume that $\mathrm{Au}^{3+}$ is reduced and assume that the reaction in the compartment containing gold is
$$\mathrm{Au}^{3+}(a q)+4 \mathrm{Cl}^{-}(a q) \rightleftharpoons \mathrm{AuCl}_{4}^{-}(a q)$$
Calculate the value of $K$ for this reaction at $25^{\circ} \mathrm{C}$.

Bhumika Jayee
Bhumika Jayee
Numerade Educator
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Problem 141

The measurement of pH using a glass electrode obeys the Nernst equation. The typical response of a pH meter at $25.00^{\circ} \mathrm{C}$ is given by the equation
$$\mathscr{C}_{\text {meas }}=\mathscr{E}_{\text {ref }}+0.05916 \mathrm{pH}$$
where $\mathscr{E}_{\text {ref }}$ contains the potential of the reference electrode and all other potentials that arise in the cell that are not related to the hydrogen ion concentration. Assume that $\mathscr{E}_{\text {ref }}=0.250 \mathrm{~V}$ and that $\mathscr{C}_{\text {tme\pi }}=0.480 \mathrm{~V}$
a. What is the uncertainty in the values of $\mathrm{pH}$ and $\left[\mathrm{H}^{+}\right]$ if the uncertainty in the measured potential is $\pm 1 \mathrm{mV}(\pm 0.001 \mathrm{~V})$ ?
b. To what precision must the potential be measured for the uncertainty in $\mathrm{pH}$ to be $\pm 0.02 \mathrm{pH}$ unit?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
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Problem 142

Zirconium is one of the few metals that retains its structural integrity upon exposure to radiation. For this reason, the fuel rods in most nuclear reactors are made of zirconium. Answer the following questions about the redox properties of zirconium based on the half-reaction
$\mathrm{ZrO}_{2} \cdot \mathrm{H}_{2} \mathrm{O}+\mathrm{H}_{2} \mathrm{O}+4 \mathrm{e}^{-} \longrightarrow \mathrm{Zr}+4 \mathrm{OH}^{-} \quad \mathscr{E}^{\circ}=-2.36 \mathrm{~V}$
a. Is zirconium metal capable of reducing water to form hydrogen gas at standard conditions?
b. Write a balanced equation for the reduction of water by zirconium metal.
c. Calculate $\mathscr{8}^{\circ}, \Delta G^{\circ}$, and $K$ for the reduction of water by zirconium metal.
d. The reduction of water by zirconium occurred during the accident at Three Mile Island, Pennsylvania, in $1979 .$ The hydrogen produced was successfully vented and no chemical explosion occurred. If $1.00 \times 10^{3} \mathrm{~kg} \mathrm{Zr}$ reacts, what mass of $\mathrm{H}_{2}$ is produced? What volume of $\mathrm{H}_{2}$ at $1.0 \mathrm{~atm}$ and $1000 .{ }^{\circ} \mathrm{C}$ is produced?
e. At Chernobyl, USSR, in 1986 , hydrogen was produced by the reaction of superheated steam with the graphite reactor core:
$$\mathrm{C}(s)+\mathrm{H}_{2} \mathrm{O}(g) \longrightarrow \mathrm{CO}(g)+\mathrm{H}_{2}(g)$$
A chemical explosion involving the hydrogen gas did occur at Chernobyl. In light of this fact, do you think it was a correct decision to vent the hydrogen and other radioactive gases into the atmosphere at Three Mile Island? Explain.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
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Problem 143

A galvanic cell is based on the following half-reactions:
$$\begin{aligned}\mathrm{Ag}^{+}+\mathrm{e}^{-} \longrightarrow \mathrm{Ag}(s) & & \mathscr{E}^{\circ}=0.80 \mathrm{~V} \\\mathrm{Cu}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{Cu}(s) & & \mathscr{6}^{\circ}=0.34 \mathrm{~V}\end{aligned}$$
In this cell, the silver compartment contains a silver electrode and excess $\mathrm{AgCl}(s)\left(K_{\mathrm{sp}}=1.6 \times 10^{-10}\right)$, and the copper compartment contains a copper electrode and $\left[\mathrm{Cu}^{2+}\right]=2.0 M$.
a. Calculate the potential for this cell at $25^{\circ} \mathrm{C}$.
b. Assuming $1.0 \mathrm{~L}$ of $2.0 \mathrm{M} \mathrm{Cu}^{2+}$ in the copper compartment, calculate the moles of $\mathrm{NH}_{3}$ that would have to be added to give a cell potential of $0.52 \mathrm{~V}$ at $25^{\circ} \mathrm{C}$ (assume no volume change on addition of $\mathrm{NH}_{3}$ ).
$$\mathrm{Cu}^{2+}(a q)+4 \mathrm{NH}_{3}(a q) \rightleftharpoons{\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{4}^{2+}(a q)} \quad K=1.0 \times 10^{13}$$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:29

Problem 144

Given the following two standard reduction potentials,
$$\mathrm{M}^{3+}+3 \mathrm{e}^{-} \longrightarrow \mathrm{M} \quad \mathscr{E}^{\circ}=-0.10 \mathrm{~V}$$
$$\mathrm{M}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{M} \quad \mathscr{E}^{\circ}=-0.50 \mathrm{~V}$$
solve for the standard reduction potential of the half-reaction$$\mathrm{M}^{3+}+\mathrm{e}^{-} \longrightarrow \mathrm{M}^{2+}$$

Teesta Dasgupta
Teesta Dasgupta
University of Pittsburgh - Main Campus
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Problem 145

You make a galvanic cell with a piece of nickel, $1.0 M \mathrm{Ni}^{2+}(a q)$, a piece of silver, and $1.0 M \mathrm{Ag}^{+}(a q) .$ Calculate the concentrations of $\mathrm{Ag}^{+}(a q)$ and $\mathrm{Ni}^{2+}(a q)$ once the cell is "dead."

Susan Hallstrom
Susan Hallstrom
Numerade Educator
04:25

Problem 146

A chemist wishes to determine the concentration of $\mathrm{CrO}_{4}^{2-}$ electrochemically. A cell is constructed consisting of a saturated calomel electrode (SCE; see Exercise 115$)$ and a silver wire coated with $\mathrm{Ag}_{2} \mathrm{Cr} \mathrm{O}_{4}$. The $\mathscr{C}^{\circ}$ value for the following halfreaction is $+0.446 \mathrm{~V}$ relative to the standard hydrogen electrode:
$$\mathrm{Ag}_{2} \mathrm{CrO}_{4}+2 \mathrm{e}^{-} \longrightarrow 2 \mathrm{Ag}+\mathrm{CrO}_{4}^{2-}$$
a. Calculate $\mathscr{E}_{\text {cell }}$ and $\Delta G$ at $25^{\circ} \mathrm{C}$ for the cell reaction when $\left[\mathrm{CrO}_{4}^{2-}\right]=1.00 \mathrm{~mol} / \mathrm{L}$
b. Write the Nernst equation for the cell. Assume that the SCE concentrations are constant.
c. If the coated silver wire is placed in a solution (at $25^{\circ} \mathrm{C}$ ) in which $\left[\mathrm{CrO}_{4}^{2-}\right]=1.00 \times 10^{-5} M$, what is the expected cell potential?
d. The measured cell potential at $25^{\circ} \mathrm{C}$ is $0.504 \mathrm{~V}$ when the coated wire is dipped into a solution of unknown $\left[\mathrm{Cr} \mathrm{O}_{4}{ }^{2-}\right]$. What is $\left[\mathrm{CrO}_{4}^{2-}\right]$ for this solution?
e. Using data from this problem and from Table $18.1$, calculate the solubility product $\left(K_{\mathrm{sp}}\right)$ for $\mathrm{Ag}_{2} \mathrm{CrO}_{4}$.

Lottie Adams
Lottie Adams
Numerade Educator
07:29

Problem 147

Consider the following galvanic cell: A $15.0-$ mol sample of $\mathrm{NH}_{3}$ is added to the Ag compartment (assume $1.00 \mathrm{~L}$ of total solution after the addition). The silver ion reacts with ammonia to form complex ions as shown:
$\mathrm{Ag}^{+}(a q)+\mathrm{NH}_{3}(a q) \rightleftharpoons \mathrm{AgNH}_{3}^{+}(a q)$
$K_{1}=2.1 \times 10^{3}$
$\mathrm{AgNH}_{3}{ }^{+}(a q)+\mathrm{NH}_{3}(a q) \rightleftharpoons \mathrm{Ag}\left(\mathrm{NH}_{3}\right)_{2}^{+}(a q)$
$K_{2}=8.2 \times 10^{3}$
Calculate the cell potential after the addition of $15.0 \mathrm{~mol} \mathrm{NH}_{3} .$

Ronald Prasad
Ronald Prasad
Numerade Educator
03:33

Problem 148

When copper reacts with nitric acid, a mixture of $\mathrm{NO}(\mathrm{g})$ and $\mathrm{NO}_{2}(g)$ is evolved. The volume ratio of the two product gases depends on the concentration of the nitric acid according to the equilibrium
$2 \mathrm{H}^{+}(a q)+2 \mathrm{NO}_{3}^{-}(a q)+\mathrm{NO}(g) \rightleftharpoons 3 \mathrm{NO}_{2}(g)+\mathrm{H}_{2} \mathrm{O}(l)$
Consider the following standard reduction potentials at $25^{\circ} \mathrm{C}$ :
$3 \mathrm{e}^{-}+4 \mathrm{H}^{+}(a q)+\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{NO}(g)+2 \mathrm{H}_{2} \mathrm{O}(l)$
$$\begin{array}{r}\mathscr{E}^{\circ}=0.957 \mathrm{~V}\end{array}$$
$\mathrm{e}^{-}+2 \mathrm{H}^{+}(a q)+\mathrm{NO}_{3}^{-}(a q) \longrightarrow \mathrm{NO}_{2}(g)+2 \mathrm{H}_{2} \mathrm{O}(l)$
$${8}^{\circ}=0.775 \mathrm{~V}$$
a. Calculate the equilibrium constant for the above reaction.
b. What concentration of nitric acid will produce a NO and $\mathrm{NO}_{2}$ mixture with only $0.20 \% \mathrm{NO}_{2}$ (by moles) at $25^{\circ} \mathrm{C}$ and $1.00 \mathrm{~atm}$ ? Assume that no other gases are present and that the change in acid concentration can be neglected.

Lottie Adams
Lottie Adams
Numerade Educator
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Problem 149

The following standard reduction potentials have been determined for the aqueous chemistry of indium:
$$\begin{array}{ll}\mathrm{In}^{3+}(a q)+2 \mathrm{e}^{-} \longrightarrow \operatorname{In}^{+}(a q) & \mathscr{E}^{\circ}=-0.444 \mathrm{~V} \\
\mathrm{In}^{+}(a q)+\mathrm{e}^{-} \longrightarrow \operatorname{In}(s) & \mathscr{E}^{\circ}=-0.126 \mathrm{~V}\end{array}$$
a. What is the equilibrium constant for the disproportionation reaction, where a species is both oxidized and reduced, shown below?
$$3 \operatorname{In}^{+}(a q) \longrightarrow 2 \operatorname{In}(s)+\operatorname{In}^{3+}(a q)$$
b. What is $\Delta G_{\mathrm{f}}^{\circ}$ for $\mathrm{In}^{+}(a q)$ if $\Delta G_{\mathrm{f}}^{\circ}=-97.9 \mathrm{~kJ} / \mathrm{mol}$ for $\mathrm{In}^{3+}(a q)$ ?

Susan Hallstrom
Susan Hallstrom
Numerade Educator
06:18

Problem 150

An electrochemical cell is set up using the following unbalanced reaction:
$$\mathrm{M}^{a+}(a q)+\mathrm{N}(s) \longrightarrow \mathrm{N}^{2+}(a q)+\mathrm{M}(s)$$
The standard reduction potentials are:
$$\begin{array}{ll}
\mathrm{M}^{a+}+a \mathrm{e}^{-} \longrightarrow \mathrm{M} & \mathscr{E}^{\circ}=+0.400 \mathrm{~V} \\
\mathrm{~N}^{2+}+2 \mathrm{e}^{-} \longrightarrow \mathrm{N} & \mathscr{8}^{\circ}=+0.240 \mathrm{~V}
\end{array}$$
The cell contains $0.10 M \mathrm{~N}^{2+}$ and produces a voltage of $0.180 \mathrm{~V}$. If the concentration of $\mathrm{M}^{a+}$ is such that the value of the reaction quotient $Q$ is $9.32 \times 10^{-3}$, calculate $\left[\mathrm{M}^{a+}\right]$. Calculate $w_{\max }$ for this electrochemical cell.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:35

Problem 151

Three electrochemical cells were connected in series so that the same quantity of electrical current passes through all three cells. In the first cell, $1.15 \mathrm{~g}$ chromium metal was deposited from a chromium(III) nitrate solution. In the second cell, $3.15 \mathrm{~g}$ osmium was deposited from a solution made of $\mathrm{Os}^{n+}$ and nitrate ions. What is the name of the salt? In the third cell, the electrical charge passed through a solution containing $\mathrm{X}^{2+}$ ions caused deposition of $2.11 \mathrm{~g}$ metallic $\mathrm{X}$. What is the electron configuration of $\mathrm{X}$ ?

Lottie Adams
Lottie Adams
Numerade Educator
11:48

Problem 152

A galvanic cell is based on the following half-reactions:
$$\begin{aligned}\mathrm{Cu}^{2+}(a q) &+2 \mathrm{e}^{-} \longrightarrow \mathrm{Cu}(s) & & 8^{\circ}=0.34 \mathrm{~V} \\
\mathrm{~V}^{2+}(a q) &+2 \mathrm{e}^{-} \longrightarrow \mathrm{V}(s) & & \mathscr{b}^{\circ} &=-1.20 \mathrm{~V}\end{aligned}$$
In this cell, the copper compartment contains a copper electrode and $\left[\mathrm{Cu}^{2+}\right]=1.00 M$, and the vanadium compartment contains a vanadium electrode and $\mathrm{V}^{2+}$ at an unknown concentration. The compartment containing the vanadium (1.00 $\mathrm{L}$ of solution) was titrated with $0.0800 \mathrm{M} \mathrm{H}_{2} \mathrm{EDTA}^{2-}$, resulting in the reaction
$$\begin{array}{r}\mathrm{H}_{2} \mathrm{EDTA}^{2-}(a q)+\mathrm{V}^{2+}(a q) \rightleftharpoons \mathrm{VEDTA}^{2-}(a q)+2 \mathrm{H}^{+}(a q) \\K=?\end{array}$$
The potential of the cell was monitored to determine the stoichiometric point for the process, which occurred at a volume of $500.0 \mathrm{~mL} \mathrm{H}_{2} \mathrm{EDTA}^{2-}$ solution added. At the stoichiometric point, $\mathscr{C}_{\text {cell }}$ was observed to be $1.98 \mathrm{~V}$. The solution was buffered at a $\mathrm{pH}$ of $10.00 .$
a. Calculate $\mathscr{E}_{\text {cell }}$ before the titration was carried out.
b. Calculate the value of the equilibrium constant, $K$, for the titration reaction.
c. Calculate $\mathscr{B}_{\text {cell }}$ at the halfway point in the titration.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
08:53

Problem 153

The table below lists the cell potentials for the 10 possible galvanic cells assembled from the metals $\mathrm{A}, \mathrm{B}, \mathrm{C}, \mathrm{D}$, and $\mathrm{E}$, and their respective $1.00 M 2+$ ions in solution. Using the data in the table, establish a standard reduction potential table similar to Table $18.1$ in the text. Assign a reduction potential of $0.00 \mathrm{~V}$ to the halfreaction that falls in the middle of the series. You should get two different tables. Explain why, and discuss what you could do to determine which table is correct.

Susan Hallstrom
Susan Hallstrom
Numerade Educator