Redox Quiz #1 Agents, Spontaneous Reactions, Oxidation #.

1. In a redox reaction, the species that loses electrons

A. is oxidized

B. is called the cathode

C. gains mass at the electrode

D. decreases in oxidation number

2. Which of the following is the strongest oxidizing agent?

A. Cu²⁺

B. Pb²⁺

C. Ni²⁺

D. Sn²⁺

3. Metallic platinum reacts spontaneously with Au3+(aq) but does not react with

Ag⁺_(aq).

The metals, in order of increasing strength as reducing agents, are

A. Ag, Pt, Au

B. Pt, Au, Ag

C. Au, Ag, Pt

D. Au, Pt, Ag

4. The oxidizing agent in the above reaction is

A. Fe²⁺

B. Fe³⁺

C. Mn²⁺

D. MnO₄^-

5. MnO₄^- + 5Fe²⁺ + 8H⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O

During the reaction, electrons transfer from

A. Fe³⁺ to Fe²⁺

B. Fe²⁺ to MnO₄^-

C. MnO₄^- to Fe²⁺

D. MnO₄^- to Mn²⁺

6. As an element is oxidized, its oxidation number

A. increases as electrons are lost

B. decreases as electrons are lost

C. increases as electrons are gained

D. decreases as electrons are gained

7. A solution of 1.0 M Pb(NO₃)₂ will not react with a container made of

A. Cu

B. Fe

C. Sn

D. Zn

8. A spontaneous redox reaction occurs when a piece of iron is placed in 1.0 M

CuSO₄. The reducing agent is

A. Fe

B. Cu²⁺

C. H₂O

D. SO₄^2-

9. A substance is oxidized when it

A. loses protons

B. gains protons

C. loses electrons

D. gains electrons

10. A strip of titanium, Ti, is placed in 1.0 M Sn(NO₃)₂. The shiny surface of the

titanium darkens, indication that a reaction has

occurred. From this observation it may be concluded that

A. Ti²⁺ is a weaker reducing agent than Sn²⁺

B. Ti²⁺ is a weaker oxidizing agent than Sn²⁺

C. Ti²⁺ is a stronger reducing agent than Sn²⁺

D. Ti²⁺ is a stronger oxidizing agent than Sn²⁺

11. Consider the following redox reaction : Hg²⁺ + Cu → Hg + Cu²⁺ . In this

reaction, Hg²⁺ is a

A. weaker reducing agent than Cu²⁺

B. weaker oxidizing agent than Cu²⁺

C. stronger reducing agent than Cu²⁺

D. stronger oxidizing agent than Cu²⁺

12. The species which gains electrons in a redox reaction

A. loses mass

B. is oxidized

C. is the oxidizing agent

D. increases in oxidization number

13. Samples of Uranium, Vanadium and Yttrium (U, V, Y) were placed in solutions

containing the metallic ions U³⁺, V²⁺, and Y³⁺. The following observations were

recorded.

Trial	Ion	Metal	Observation
1	U^3+	Y	reaction
2	V^2+	U	reaction
3	V^2+	Y	reaction
4	Y^3+	V	no reaction

The oxidizing agents from the strongest to the weakest are

A. V²⁺, U³⁺, Y³⁺

B. U³⁺, V²⁺, Y³⁺

C. Y³⁺, U³⁺, V²⁺

D. V²⁺, Y³⁺, U³⁺

14. Use the data below to answer the question.
Mo3+(aq) + Ir(s) ® no observable reaction
Ir3+(aq) + Nd(s) ® Nd3+(aq) + Ir(s)
Mo3+(aq) + Nd(s) ® Nd3+(aq) + Mo(s)
From these data it can be predicted that the oxidizing agents, listed from strongest

to weakest, are:
A. Ir³⁺ Mo³⁺ Nd³⁺
B. Mo³⁺ Nd³⁺ Ir³⁺
C. Ir³⁺ Nd³⁺ Mo³⁺
D. Mo Ir Nd

15. Which process could cause X^2-_(aq) to change to X⁺_(aq)?

A. Z(s) ® Z3-(aq)
B. Z(s) ® Z3+(aq)
C. Z2-(aq) ® Z+(aq)
D. Z3-(aq) ® Z(s)

16. In the reaction, what is the reducing agent?

4 Zn_(s) + 10 H⁺_(aq) + NO₃^-_(aq) ® NH₄⁺_(aq) + 4 Zn²⁺_(aq) + 3 H₂O_(l)
A. Zn_(s)
B. H⁺_(aq)
C. Zn²⁺_(aq)
D. NO₃^-_(aq)

17. A student observed the reactions between four different metals and the solutions

of their ions, and then recorded these 'spontaneous' reactions.
I. W_(s) + X⁺_(aq) ® W⁺_(aq) + X_(s)
II. X_(s) + Y⁺_(aq) ® X⁺_(aq) + Y_(s)
III. Y_(s) + Z⁺_(aq) ® Y⁺_(aq) + Z_(s)
IV. X_(s) + W⁺_(aq) ® X⁺_(aq) + W_(s)
V. X_(s) + Z⁺_(aq) ® X⁺_(aq) + Z_(s)
If equation I is correct, which equation did the student record incorrectly?
A. II
B. III
C. IV
D. V

18. The reaction below proceeds spontaneously.
A2+(aq) + X(s) ® A(s) + X2+(aq)
Elements A(s) and X(s) respectively, could be

A. Cr²⁺ and Co
B. Pb²⁺ and Cu
C. Co²⁺ and Cu
D. Ni²⁺ and Zn

19. A piece of Sn_(s) was placed in the following solutions:
I. Cu(NO₃)_2(aq)
II. Hg(NO₃)_2(aq)
III. AgNO_3(aq)
IV. Fe(NO₃)_2(aq)
A spontaneous reaction will occur in all solutions except
A. I
B. II
C. III
D. IV

20. Theoretically, a reducing agent can be described as a substance that
A. loses electrons and becomes reduced.
B. loses electrons and causes reduction.
C. gains electrons and causes oxidation.
D. gains electrons and becomes reduced.

21. In the reaction
Cu_(s) + 2Ag⁺_(aq) ® Cu²⁺_(aq) + 2Ag_(s)
A. Cu_(s) is reduced by the oxidizing agent.
B. Ag⁺_(aq) is the reducing agent and Cu_(s) is reduced.
C. Cu_(s) is the reducing agent and Ag⁺_(aq) is reduced.
D. Cu_(s) is the oxidizing agent and Ag⁺_(aq) is oxidized.

22. Which of the following reactions is non-spontaneous?
A. I2(s) + Fe(s) ® 2I-(aq) + Fe2+(aq)
B. Ni2+(aq) + Sn2+(aq) ® Ni(s) + Sn4+(aq)
C. 2Li(s) + 2H2O(l) ® 2Li+(aq) + 2 OH-(aq) + H2(g)
D. 2Cl2(g) + 2 H2O(l) ® 4Cl-(aq) + O2(g) + 4H+(aq)

23. Which of the following best describes the process of oxidation?

A. the process in which oxygen is produced

B. the process in which electrons are added

C. the process in which the oxidation number decreases

D. the process in which the oxidation number increases

24. What is the oxidation number of N in the mercury (II) compound Hg(NH₃)₂Cl₂

A. -6

B. -4

C. -3

D. +2

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. Identify the substance that is oxidized in the following equation:

Br₂ + SO_2(g) + K₂SO₄ + 2H₂O ® H₂SO₄ + 2KBr

A. Br₂

B. SO₂

C. H₂O

D. K₂SO₄

27 What is the reducing agent in the following equation?

Fe²⁺ + 2I^- ® Fe_(s) + I_2(s)

A. I₂

B. I^-

C. Fe²⁺

D. Fe³⁺

28. What is the oxidation number of C in the C₃H₅O₂^- ion ?

A. -1/3

B. -2/3

C. -1

D. -2

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

1.0 M solution of Cu(NO₃)₂?

A. The solution turns a darker blue.

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.

30. Identify the reducing agent in the following equation:

Zn + 2MnO₂ + H₂O ⇌ Zn(OH)₂ + 2MnO(OH)

A. Zn

B. H₂O

C. MnO₂

D. Zn(OH)₂