Section 21.1–Introduction to Electrochemistry
Extra Q’s: Heath: p.621#1-4 ; Hebden p.192 #1-2,
Name:
Date:
1. The species which gains electrons in a redox reaction 9601
A. loses mass.
B. is oxidized.
C. is the oxidizing agent. D. increases in oxidation number.
7. A substance is oxidized when it 9708
A. loses protons.
B. gains protons.
C. loses electrons.
D. gains electrons.
2. In an oxidation half–reaction there is a 9604
A. gain of protons.
B. gain of electrons.
C. loss of protons.
D. loss of electrons.
8. Which of the following is capable of acting both as an
oxidizing agent and a reducing agent? 9906
A. H 
B. Na 
C. Sn D. MnO4
3. An oxidizing agent 9604
A. loses electrons.
B. decreases in oxidation number.
C. loses mass in an operating electrochemical cell.
D. acts as an anode in an operating electrochemical cell.
9. Consider the following reaction: 0001
Each oxygen atom is
A. reduced and loses 2e–
C. oxidized and loses 2e–
4. In a redox reaction, the species which loses electrons 9606
A. is oxidized.
B. is called the cathode.
C. gains mass at the electrode.
D. decreases in oxidation number.
B. reduced and gains 2e–
D. oxidized and gains 2e–
PART B: Written Response:
1. Define the term oxidation–reduction reaction. (2 marks)
9808
5. A spontaneous redox reaction occurs when a piece of iron is
placed in 1.0 M CuSO4 .The reducing agent is 9701
Fe + CuSO4  FeSO4 + Cu
Fe + Cu2+  Fe2+ + Cu
A reaction where electrons are
transferred and one species ends up
losing electrons and one species ends
up gaining electrons.
A. Fe
B. Cu 
C. H2O
D. SO4

6. An oxidizing agent is a substance which 0
A. accepts protons.
B. donates protons.
C. accepts electrons.
D. donates electrons.
21-1 MC ANS.
1.C 2.D 3.B 4.A. 5.A
6.C 7.C 8.C 9.B
Name:
Section 21.2–Oxidation Numbers
Extra Questions: Heath p.627 #1-4 , Hebden pp. 194-5 #3-6
Date:
1. Consider the following redox reaction: 9601

The species which loses electrons is
A. Cl2
B. Cr3+
C. H2O
D. Cr2O7
2. The oxidation number of carbon in CaC2O4 is 9601
A. +2
B. +3
C. +4
D. +6
3. When MnO4reacts to form Mn, the manganese in MnO4is
9601
A. reduced as its oxidation number increases.
B. reduced as its oxidation number decreases.
C. oxidized as its oxidation number increases.
D. oxidized as its oxidation number decreases.
Section 21.1 & 21.2- Definitions & Oxidation Numbers p 1 o f 2
4. The oxidation number of nitrogen increases in 9604
5. Consider the following redox equation: 9606

The reducing agent is
A. I2
B. H

C. Fe2+
D. IO3
6. When NO2 reacts to form N2O4 the oxidation number of
nitrogen 9606
A. increases by 2.
B. increases by 4.
C. increases by 8.
D. does not change.
A. reduction. B. oxidation. C. electrolysis. D. neutralization.
Use the following reaction to answer questions 7 and 8.
18. Which of the following represents a redox reaction? 9801
7. During the reaction, electrons transfer from
A. Feto Fe 
B. Feto MnO4

 
C. MnO4 to Fe
D. MnO4to Mn

8. The oxidizing agent GER in the above reaction is
A. Fe 
B. Fe 
C. Mn 
D. MnO4

9. Consider the following half–reaction: 9608
19. The oxidation number of carbon in C2O42–is 9801
A. +3
B. +4
C. +5
D. +6
20. Consider the following redox reaction: 9801
+3 0
The oxidizing agent is
A. H 
B. H2O
The oxidation number of antimony in Sb2O3
A. increases by 3.
B. increases by 6.
C. decreases by 3.
D. decreases by 6.
D. As2O3
21. When W2O5 is converted to WO2 in a redox reaction, the W
has been 9801
A. reduced since its oxidation number has increased.
B. reduced since its oxidation number has decreased.
C. oxidized since its oxidation number has increased.
D. oxidized since its oxidation number has decreased.
10. As an element is oxidized, its oxidation number 9608
A. increases as electrons are lost.
B. decreases as electrons are lost.
C. increases as electrons are gained.
D. decreases as electrons are gained.
22. Which of the following is an equation representing a redox
reaction? 9806
11. Consider the following redox reaction: 9701
The species that loses electrons is
A. H2O
B. MnO4
C. CH3CHO
C. NO3
D. CH3COOH
12. The oxidation number of platinum in Pt(H2O)4is 9701
A. +2
B. 0
C. +4
D. 1/2
13. Consider the following oxidation–reduction reaction: 9706

The reducing agent is
A. I2
B. IO3 
C. H2O

14. Consider the following redox reaction:
D. Mn

The reducing agent is 9708

A. I
B. I2
C. H 
D. ClO3

15. Which equation represents a redox reaction? 9708


16. Nitrogen has an oxidation number of zero in 9708
A. N2
B. NO2
C. NH3
D. HNO3
17. Consider the following redox reaction: 9708
The nitrogen in HNO3 undergoes
Section 21.1 & 21.2- Definitions & Oxidation Numbers p 2 o f 3
23. A product of the oxidation of NO2 is 9806
A. NO
B. N2O
C. NO2 

24. A product of the oxidation of MnO2 is 9808
A. Mn
B. Mn 
C. MnO4
D. NO3
D. Mn2O3
25. Consider the following:
In the redox reaction above, 9808
A. hydrogen is both reduced and oxidized.
B. manganese is both reduced and oxidized.
C. manganese is reduced and hydrogen is oxidized.
D. manganese is oxidized and hydrogen is reduced.
26. The oxidation number of phosphorus in Na4P2O7 is 9808
A. –10
B. –5
C. +5
D. +10
27. Consider the following: 9808

In this redox reaction, the chemical species SO2 is
A. reduced and the oxidation number of oxygen increases.
B. reduced and the oxidation number of oxygen decreases.
C. oxidized and the oxidation number of sulphur increases.
D. oxidized and the oxidation number of sulphur decreases.
28. Consider the following redox reaction: 9901

The reducing agent is
A. H2O
B. ClO3
D. MnO4
C. MnO2
29. Consider the following reaction that occurs in a breathalyzer:
9901
Which atom undergoes an increase in oxidation number?
A. carbon
B. oxygen
C. hydrogen
D. chromium
30. Consider the following redox reaction:
The substance undergoing reduction is 9906
A. O2
B. CO2
C. H2O
D. C6H12O6
21-2 MC ANS:
1.B 2.B 3.B 4.D 5.C
6.D 7.B 8.D 9.C 10.A
11.C 12.A 13.D 14.A
15.C 16.A 17.A 18.B
19.A 20.C 21.B 22.B
23.D 24.C 25.B 26.C
27.C 28.B 29.A 30.A
Section 21.1 & 21.2- Definitions & Oxidation Numbers p 3 o f 3