Redox Quiz #3 Balancing Redox reactions- Acid & Base Cell Potentials

1. Consider the following overall reaction:

2Rh⁺ + Pb_(s) → 2Rh_(s) + Pb^2+- E⁰ = 0.73 V

The E⁰ for the half-reaction Rh⁺ + e^- ⇄ Rh is

A. -0.86 V

B. -0.60 V

C. +0.60 V

D. +0.86 V

2. Which of the following systems would be correct if the zinc half-cell would havebeen chosen as

            the standard instead of the hydrogen half-cell?

A. The reduction potentials of all the half-cells would remain unchanged

B. The reduction potentials of all the half-cells would increase by 0.76 V

C. The reduction potentials of all the half-cells would have positive values

D. The reduction potentials of the hydrogen half-cell decrease by 0.76 V

3. Three beakers contain 1.0 M CuCl₂. A piece of metal is placed in each of the

beakers

BEAKER	SOLUTION	METAL
1	CuCl2	Zn
2	CuCl2	Ag
3	CuCl2	Ni

Reactions occur in

A beaker 2 only

B. beakers 1, 2, and 3

C. beakers 1 and 2 only

D. beakers 1 and 3 only

4. Consider the following redox reaction:

3SO₂ + 3H₂O + ClO₃^- → 3SO₄^2- + 6H⁺ + Cl^-

The reduction half-reaction is

A. ClO₃^- + 6H⁺ → Cl^- + 3H₂O + 6e^-

B. ClO₃^- + 6H⁺ + 6e^- → Cl ^- + 3H₂O

C. SO₂ + 2H₂O → SO₄^2- + 4H⁺ + 2e^-

D. SO₂ + 2H₂O + 2e^- → SO₄^2- + 4H⁺

5. What two substances are produced when Cr and 1.0 M MnO₄^- react in a basic solution?

A. Mn²⁺ and Cr³⁺

B. MnO₂ and Cr³⁺

C. Mn²⁺ and Cr²⁺

D. MnO₂ and CrO₄^2-

6. Bromine, Br₂, will react spontaneously with

A. I^-

B. I₂

C. Cl^-

D. Cl₂

7. The substances H₂O₂, H₃PO₄ and H₂SO₃ in order of increasing strengths as

oxidizing agents are.

A H₂O₂, H₃PO₄, H₂SO₃

B. H₂SO_3, H₃PO₄, H₂O₂

C. H₃PO₄, H₂SO_{3 ,} H₂O₂

D. H₂O_{2,H2SO3 ,} H₃PO₄

8. Consider the following overall equation for an electrochemical cell:

3Ag⁺ + Cr → Cr³⁺ + 3Ag

At standard conditions ,the initial cell voltage is

A. +0.06 V

B. +0.39 V

C. +1.21 V

D. +1.54

9. A solution of 1.0 M Co(NO₃)₂ should be stored in a container made of

A. tin

B. zinc

C. aluminum

D. magnesium

10. A strong oxidizing agent has a

A. weak attraction for electrons

B. strong attraction for electrons

C. weak ability to become reduced

D. strong ability to become oxidized

11. The two species which react spontaneously in acidic solutions are

A. IO₃^- and I₂

B. SO₄^2- and S

C. BrO₃^- and Br ^-

D. AuCl₄^- and Au

12. Consider the following redox reaction:

Co2+(aq) + 2Ag(s) → 2Ag+(aq) + Co(s)

The reaction is

A. spontaneous and E^o is positive.

B. spontaneous and E^o is negative.

C. non-spontaneous and E^o is positive.

D. non-spontaneous and E^o is negative

13. Referring to the data booklet, which of the following can act as an oxidizing agent but not as a reducing agent?

A. Zn

B. Cl^-

C. Sn²⁺

D. Fe³⁺

14. Which equation represents a redox reaction?

A. Pb²⁺ + 2Cl^- → PbCl₂

B. CaO + CO₂ → CaCO₃

C. Mg + 2HCl → MgCl₂ + H₂

D. HCl + NaOH → NaCl + H₂O

15. In a redox reaction, ClO^- was converted to Cl^- in a basic solution. The balanced half-reaction for this process is

A. ClO^- + H₂O + 2e^- → Cl^- + 2OH^-

B. ClO^- + 2OH^- → Cl^- + 2e^- + H₂O

C. ClO^- + H₂O → Cl^- + 2e^- + 2OH^-

D. ClO^- + 2OH^- + 2e^- → Cl^- + H₂O

16. Which of the following gives the correct oxidation numbers for the nitrogen atoms in all three chemical species?

N₂ Li₃N NO₂^-

A. 0 -3 +3

B. -3 -3 +3

C. 0 +3 -3

D. -3 -3 -3

17. The oxidation number of manganese changes as MnO₄- is converted to MnO₂How many electrons are

            gained or lost by the manganese during the change?

A. 1e^- lost

B. 1e^- gained

C. 3e^- lost

D. 3e^- gained

18. Which of the solutions listed below should NOT be stored in a tin-plated container?
I NaNO_3(aq) II AgNO_3(aq) III SnBr_2(aq) IV Cl_2(aq)
A. I only
B. II and IV
C. II, III and IV
D. II and III

19. If fluorine gas is bubbled through NaI_(aq),

A. Na⁺_(aq) is reduced
B. I^-_(aq) is oxidized
C. F_2(aq) is oxidized
D. I^-_(aq) is reduced

20. A high school laboratory's waste container is used to dispose of aqueous

solutions of sodium nitrate, potassium sulfate, hydrochloric acid, and tin (II)

chloride. The most likely net redox reaction predicted to occur inside the waste

container is represented by the equation:

A. Sn²⁺_(aq) + 2NO₃^-_(aq) + 4H⁺_(aq) ® 2NO_(g) + 2H₂O_(l) + Sn⁴⁺_(aq)
B. 2 H⁺_(aq) + 2K⁺_(aq) ® H_2(g) + K_(s)
C. SO₄^2-_(aq) + 4H⁺_(aq) + 2 Cl^-_(aq) ® H₂SO_3(aq) + H₂O_(l) + Cl_2(g)
D. Cl_2(g) + Sn²⁺_(aq) ® Cl^-_(aq) + Sn_(s)

21. The net ionic equation for the reaction between aqueous solutions of tin (II)

bromide and iron (III) nitrate is

A. Sn2+(aq) + NO3-(aq) ® NO2(g) + Sn4+(aq)
B. Sn2+(aq) + 2 Fe3+(aq) ® Sn4+(aq) + 2 Fe2+(aq)
C. 2Sn2+(aq) + Fe3+(aq) ® 2 Sn3+(aq) + Fe2+(aq)
D. Sn2+(aq) + 2NO3-(aq) ® 2NO2(g) + Sn4+(aq

22. Use the following unbalanced redox reaction to answer this question.

__O_2(g) + ___H⁺_(aq) + ___Ag_(s) ® __Ag⁺_(aq) + ___H₂O_(l)

The coefficients for the balanced equation are
A. 1,4,4,4,2
B. 1,4,1,1,2
C. 1,2,1,1,1
D. 1,1,1,1,1

23. A student mixes various combinations of the metals Pd, Cd and Ga with 1.0 M

solutions of their ions. The student then measures the voltages and puts them in

the table below.

1 Ga Pd²⁺ +1.18 V

2 Ga Cd²⁺ +0.16 V

3 Cd Pd²⁺?

What voltage is produced by reaction # 3?

A. -1.34 V

B. -1.02 V

C. +1.02 V

D. +1.34 V

24. Which of the following is a correctly balanced reduction half-reaction?

A. 2HCN + 2e^- ® C₂N₂ + 2H⁺

B. 2Sb + 3H₂O + 6e^- ® Sb₂O₃ + 6H⁺

C. NO₃^- + 3H⁺ + 3e^- ® HNO₂ + H₂O

D. Sb₂O₅ + 6H⁺ + 4e^- ® 2Sb(OH)₂⁺ + H₂O

25. Which of the following combinations will react spontaneously under standard

conditions?

A. Ag + Br₂

B. Ni + Co²⁺

C. Zn + Mg²⁺

D. Au + HNO₃

26. Which of the following best describes what happens when lead solid is placed in a

1.0 M solution of Cu(NO₃)₂?

A. Bubbles form on the lead.

B. No changes are observed.

C. Copper solid forms on the lead and the solution changes colour.

D. The mass of lead solid increases and the solution does not change colour.

27. Consider the following unbalanced equation for a redox reaction in acidic

solution: Br^- + BrO₃^- ® Br₂

What is the equation for the balanced reduction half-reaction?

A. 2Br^- ® Br₂ + 2e^-

B.        2Br^-   +    2e^- ®   Br₂

C. 5e^- + 6H⁺ + 2BrO₃^- ® Br₂ + 3H₂O

D.        10e^-  + 12H⁺    +    2BrO₃^- ®  Br₂   +  6H₂O

28. What reaction will occur when a solution containing 1.0 M MgSO₄ and 1.0 M

CoCl₂ is stored in a galvanized (Zn coated) bucket?

A. Mg_{(s) +} Cl₂ ® MgCl_2(s)

B. Co²⁺ + SO₄^2- ® CoSO_4(s)

C. Co^{2+ +} Zn_(s) ® Zn²⁺ + Co_(s)

D. Mg²⁺ + Zn_(s) ® Zn²⁺ + Mg_(s)

29. When the skeletal equation I^- ® IO₃^- is balanced in acidic solution, H₂O, H⁺

and e^- will appear. Which of the following are the correct balancing coefficients?

H₂O H⁺ e^-

A. 3 3 2

B. 3 6 6

C. 3 6 5

D. 6 12 10

30. Consider the following balanced redox equation in acidic solution:

5H₂O + 2CoCl₂ + OCl^- ® 2Co(OH)₃ + 5Cl^- + 4H⁺

Which of the following describes the amounts and locations of OH^- and H₂O if

the equation is balanced in basic solution?

A. 1H₂O on the left and no OH^-

B.        1H₂O on the left and 4OH^- on the left

C. 5H₂O on the left and 4OH^- on the left

D. 1H₂O on the left and 4OH^- on the right