Electrochemistry and Redox (MC)

Question 1

What is the standard cell potential of galvanic cell Z?

a. 0.26 V
b. 0.78 V
c. 2.34 V
d. 3.22 V

Answer 1

B

Question 2

In galvanic cells Y and Z, which of the following takes place in half cell 3?

a. Reduction occurs in both cell Y and cell Z.
b. Oxidation occurs in both cell Y and cell Z.
c. Reduction occurs in cell Y, and oxidation occurs in cell Z.
d. Oxidation occurs in cell Y, and reduction occurs in cell Z.

Answer 2

C

Question 3

If the half cell containing 1.00 M Fe(NO₃)₂(aq) in galvanic cells Y and Z is replaced with a half cell containing 5.00 M Fe(NO₃)₂(aq), what will be the effect on the cell voltage of the two galvanic cells?

a. The voltage will increase in both cells.
b. The voltage will decrease in both cells.
c. The voltage will increase in cell Y and decrease in cell Z.
d. The voltage will decrease in cell Y and increase in cell Z.

Answer 3

C

Question 4

…LiHCO₃(aq) + …H₂SO₄(aq) ⇒ …Li₂SO₄(aq) + …H₂O(l) + …CO₂(g)

When the equation above is balanced and the coefficients are reduced to lowest whole-number terms, what is the coefficient of H₂O(l)?

a. 1
b. 2
c. 3
d. 4
e. 5

Answer 4

B

Question 5

Al³⁺(aq) + 3e^- ⇒ Al(s) Eº = -1.66 V

Ag⁺(aq) + e^- ⇒ Ag(s) Eº = +0.80 V

According to the standard reduction potentials given above, what is the standard cell potential for the reaction represented below?

3Ag⁺(aq) + Al(s) ⇒ 3Ag(s) + Al³⁺(aq)

a. -1.74 V
b. -0.86 V
c. +1.74 V
d. +2.46 V
e. +4.06 V

Answer 5

D

Question 6

Oxygen is acting as an oxidizing agent in all of the following reactions EXCEPT

a. 2C(s) + O₂(g) ⇒ 2CO(g)
b. S(s) + O₂(g) ⇒ SO₂(g)
c. 2F₂(g) + O₂(g) ⇒ 2OF₂(g)
d. 2Na(s) + O₂(g) ⇒ Na₂O₂(s)
e. 2Mg(s) + O₂(g) ⇒ 2MgO(s)

Answer 6

C

Question 7

A 1 mol sample of zinc can reduce the greatest number of moles of which of the following ions?

a. Al³⁺
b. Pb²⁺
c. Ag⁺
d. Cl^-
e. N^3-

Answer 7

C

Question 8

Cu²⁺(aq) + 2e^- ⇒ Cu(s) Eº = 0.34 V

Cr³⁺(aq) + e^- ⇒ Cr²⁺(aq) Eº = -0.41 V

According to the half-reactions represented above, which of the following occurs in aqueous solutions under standard conditions?

a. Cu²⁺(aq) + Cr³⁺(aq) ⇒ Cu(s) + Cr²⁺(aq)
b. Cu²⁺(aq) + 2Cr²⁺(aq) ⇒ Cu(s) + 2Cr³⁺(aq)
c. Cu(s) + 2Cr³⁺(aq) ⇒ Cu²⁺(aq) + 2Cr²⁺(aq)
d. Cu(s) + Cr³⁺(aq) ⇒ Cu²⁺(aq) + Cr²⁺(aq)
e. 2Cu²⁺(aq) + Cr³⁺(aq) ⇒ 2Cu(s) + Cr²⁺(aq)

Answer 8

B

Question 9

Cl₂(g) + 2I^-(aq) ⇒ 2Cl^-(aq) + I₂(aq)

Which of the following best accounts for the fact that a galvanic cell based on the reaction represented above will generate electricity?

a. Cl₂ can easily lose two electrons
b. Cl₂ is a stronger oxidating agent than I₂
c. I atoms have more electrons than do atoms of Cl
d. I^- is a more stable species than I₂
e. I₂(s) is more soluble than Cl₂(g)

Answer 9

B

Question 10

2MnO₄^-(aq) + 10Br^-(aq) + 16H⁺(aq) ⇒ 2Mn²⁺(aq) + 5Br₂(aq) + 8H₂O(l)

How many electrons are transferred in the reaction represented by the balanced equation above?

a. 2
b. 4
c. 5
d. 8
e. 10

Answer 10

E

Question 11

…H⁺(aq) + …NO₂^-(aq) + …Cr₂O₇^2-(aq) ⇒ …Cr³⁺(aq) + …NO₃^-(aq) + …H₂O(l)

When the equation above is balanced and all coefficients are reduced to lowest whole-number terms, the coefficient for H₂O is

a. 2
b. 4
c. 5
d. 6
e. 8

Answer 11

B

Question 12

An electric current of 1.00 ampere is passed through an aqueous solution of Ni(NO₃)₂. How long will it take to plate out exactly 1.00 mol of nickel metal, assuming 100 percent current efficiency? (1 faraday = 96,500 coulombs = 6.02 x 10²³ electrons)

a. 386,000 sec
b. 193,000 sec
c. 96,500 sec
d. 48,200 sec
e. 24,100 sec

Answer 12

B

Question 13

A precipitation reaction.

a. H₂SeO₄(aq) + 2Cl^-(aq) + 2H⁺(aq) ⇒ H₂SeO₃(aq) + Cl₂(g) + H₂O(l)
b. S₈(s) + 8O₂(g) ⇒ SO₂(g)
c. 3Br₂(aq) + 6OH^-(aq) ⇒ 5Br^-(aq) + BrO₃^-(aq) + 3H₂O(l)
d. Ca²⁺(aq) + SO₄^2-(aq) ⇒ CaSO₄(s)
e. PtCl₄(s) + 2Cl^-(aq) ⇒ PtCl₆^2-(aq)

Answer 13

D

Question 14

A reaction that produces a coordination complex.

a. H2SeO4(aq) + 2Cl-(aq) + 2H+(aq) ⇒ H2SeO3(aq) + Cl2(g) + H2O(l)
b. S8(s) + 8O2(g) ⇒ SO2(g)
c. 3Br2(aq) + 6OH-(aq) ⇒ 5Br-(aq) + BrO3-(aq) + 3H2O(l)
d. Ca2+(aq) + SO42-(aq) ⇒ CaSO4(s)
e. PtCl4(s) + 2Cl-(aq) ⇒ PtCl62-(aq)

Answer 14

E

Question 15

A reaction in which the same reactant undergoes both oxidation and reduction.

a. H2SeO4(aq) + 2Cl-(aq) + 2H+(aq) ⇒ H2SeO3(aq) + Cl2(g) + H2O(l)
b. S8(s) + 8O2(g) ⇒ SO2(g)
c. 3Br2(aq) + 6OH-(aq) ⇒ 5Br-(aq) + BrO3-(aq) + 3H2O(l)
d. Ca2+(aq) + SO42-(aq) ⇒ CaSO4(s)
e. PtCl4(s) + 2Cl-(aq) ⇒ PtCl62-(aq)

Answer 15

C

Question 16

A combustion reaction.

a. H2SeO4(aq) + 2Cl-(aq) + 2H+(aq) ⇒ H2SeO3(aq) + Cl2(g) + H2O(l)
b. S8(s) + 8O2(g) ⇒ SO2(g)
c. 3Br2(aq) + 6OH-(aq) ⇒ 5Br-(aq) + BrO3-(aq) + 3H2O(l)
d. Ca2+(aq) + SO42-(aq) ⇒ CaSO4(s)
e. PtCl4(s) + 2Cl-(aq) ⇒ PtCl62-(aq)

Answer 16

B

Question 17

In which of the following species does sulfur have the same oxidation number as it does in H₂SO₄?

a. H₂SO₃
b. S₂O₃^2-
c. S^2-
d. S₈
e. SO₂Cl₂

Answer 17

E

Question 18

…Cr₂O₇^2-(aq) + …H₂S(g) + …H⁺(aq) ⇒ …Cr³⁺(aq) + …S(s) + …H₂O(l)

When the equation above is correctly balanced and all coefficients are reduced to lowest whole-number terms, the coefficient for H⁺(aq) is

a. 2
b. 4
c. 6
d. 8
e. 14

Answer 18

D

Question 19

3Cu(s) + 8H⁺(aq) + 2NO₃^-(aq) ⇒ 3Cu²⁺(aq) + 2NO(g) + 4H₂O(l)

True statements about the reaction represented above include which of the following?

I. Cu(s) acts as an oxidizing agent.

II. The oxidation state of nitrogen changes from +5 to +2.

III. Hydrogen ions are oxidized to form H₂O(l).

a. I only
b. II only
c. III only
d. I and II
e. II and III

Answer 19

B

Question 20

2H₂O(l) + MnO₄^-(aq) + 3ClO₂^-(aq) ⇒ 4MnO₂(s) + 3ClO₄^-(aq) + 4OH^-(aq)

According to the balanced equation above, how many moles of ClO₂^-(aq) are needed to react completely with 20. mL or 0.20 M KMnO₄ solution?

a. 0.0030 mol
b. 0.0053 mol
c. 0.0075 mol
d. 0.013 mol
e. 0.030 mol

Answer 20

A

Question 21

In the electroplating of nickel, 0.200 faraday of electrical charge is passed through a solution of NiSO₄. What mass of nickel is deposited?

a. 2.94 g
b. 5.87 g
c. 11.7 g
d. 58.7 g
e. 294 g

Answer 21

B

Question 22

What mass of Au is produced when 0.0500 mol of Au₂S₃ is reduced completely with excess H₂?

a. 9.85 g
b. 19.7 g
c. 24.5 g
d. 39.4 g
e. 48.9 g

Answer 22

B

Question 23

…Li₃N(s) + …H₂O(l) ⇒ …Li⁺(aq) + …OH^-(aq) + …NH₃(g)

When the equation above is balanced and all coefficients reduced to lowest whole number terms, the coefficient for OH^-(aq) is

a. 1
b. 2
c. 3
d. 4
e. 6

Answer 23

C

Question 24

M(s) + 3Ag⁺(aq) ⇒ 3Ag(s) + M³⁺(aq) E = +2.46 V

Ag⁺(aq) + e^- ⇒ Ag(s) E = +0.80 V

According to the information above, what is the standard reduction potential for the half-reaction M³⁺(aq) + 3e^- ⇒ M(s)?

a. -1.66 V
b. -0.06 V
c. 0.06 V
d. 1.66 V
e. 3.26 V

Answer 24

A

Question 25

Utilized as a coating to protect Fe from corrosion

a. Pb
b. Ca
c. Zn
d. As
e. Na

Answer 25

C

Question 26

Is added to silicon to enhance its properties as a semiconductor

a. Pb
b. Ca
c. Zn
d. As
e. Na

Answer 26

D

Question 27

Utilized as a shield from sources of radiation

a. Pb
b. Ca
c. Zn
d. As
e. Na

Answer 27

A

Question 28

2H₂O + 4MnO₄^- + 3ClO₂^- ⇒ 4MnO₂ + 3ClO₄^- + 4OH^-

Which species acts as an oxidizing agent in the reaction represented above?

a. H₂O
b. ClO₄^-
c. ClO₂^-
d. MnO₂
e. MnO₄^-

Answer 28

E

Question 29

In which of the following compounds is the mass ratio of chromium to oxygen closest to 1.62 to 1.00?

a. CrO₃
b. CrO₂
c. CrO
d. Cr₂O
e. Cr₂O₃

Answer 29

B

Question 30

…Ag⁺ + …AsH₃(g) + …OH^- ⇒ …Ag(s) + …H₃AsO₃(aq) + …H₂O

When the equation above is balanced with lowest whole-number coefficients, the coefficient for OH^- is

a. 2
b. 4
c. 5
d. 6
e. 7

Answer 30

D

Question 31

When an aqueous solution of NaOH is added to an aqueous solution of potassium dichromate, K₂Cr₂O₇, the dichromate ion is converted to

a. CrO₄^2-
b. CrO₂
c. Cr³⁺
d. Cr₂O₃(s)
e. Cr(OH)₃(s)

Answer 31

A

Question 32

Zn(s) + Cu²⁺ ⇒ Zn²⁺ + Cu(s)

An electrolytic cell based on the reaction represented above was constructed from zinc and copper half-cells. The observed voltage was found to be 1.00 volt instead of the standard cell potential, Eº, of 1.10 volts. Which of the following could currectly account for this observation?

a. The copper electrode was larger than the zinc electrode.
b. The Zn²⁺ electrolyte was Zn(NO₃)₂, while the Cu²⁺ electrolyte was CuSO₄.
c. The Zn²⁺ solution was more concentrated than the Cu²⁺ solution.
d. The solutions in the half-cells had different volumes.
e. The salt bridge contained KCl as the electrolyte.

Answer 32

C

Question 33

What is the maximum mass of copper that could be plated out by electrolyzing aqueous CuCl₂ for 16.0 hours at a constant current of 3.00 amperes? (1 faraday = 96,500 coulombs)

a. 28 grams
b. 57 grams
c. 64 grams
d. 114 grams
e. 128 grams

Answer 33

B

Question 34

…Fe(OH)₂ + …O₂ + …H₂O ⇒ …Fe(OH)₃

If 1 mole of O₂ oxidizes Fe(OH)₂ according to the reaction represented above, how many moles of Fe(OH)₃ can be formed?

a. 2
b. 3
c. 4
d. 5
e. 6

Answer 34

C

Question 35

A direct-current power supply of low voltage (less than 10 volts) has lost the markings that indicate which output terminal is positive and which is negative. A chemist suggests that the power supply terminals be connected to a pair of platinum electrodes that dip into 0.1-molar KI solution. Which of the following correctly identifies the polarities of the power supply terminals?

a. A gas will be evolved only at the positive electrode.
b. A gas will be evolved only at the negative electrode.
c. A brown color will appear in the solution near the negative electrode.
d. A metal will be deposited on the positive electrode.
e. None of the methods above will identify the polarities of the power supply terminals.

Answer 35

B