Download Electrochemistry Basics

5/26/2011
Electrochemistry Basics
Name:_______________________
ELECTROCHEMISTRY (OXIDATION-REDUCTION REACTIONS)
1.
What is the oxidation number of oxygen in HSO4 -?
6.
What is the oxidation number of iodine in NaIO3 ?
1. +1
3. +6
1. +1
3. +3
2. -2
4. -4
2. +5
4. +6
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-------------2.
Which change occurs when an Sn 2+ ion is oxidized?
1. Two electrons are lost.
2. Two electrons are gained.
3. Two protons are lost.
4. Two protons are gained.
7.
In which species does hydrogen have an oxidation number of 1?
1. H2 O
3. NaH
2. H2
4. NaOH
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-------------3.
Which group contains an element that can have only a
negative oxidation number (-1) in compounds?
1. 1 (IA)
3. 16 (VIA)
2. 2 (IIA)
4. 17 (VIIA)
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4.
In which compound does sulfur have an oxidation number of 2?
1. SO2
2. SO3
3. Na2 S
4. Na2 SO4
-------------5.
In which compound does chlorine have an oxidation number of
+7?
1. HClO4
3. HClO2
2. HClO3
4. HClO
8.
In which substance does sulfur have an oxidation state of +4?
1. H2 S
3. SO3
2. S
4. SO2
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9.
What is the oxidation number of chlorine in HClO4 ?
1. +1
3. +3
2. +5
4. +7
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10.
What is the oxidation number of carbon in NaHCO3 ?
1. +6
3. -4
2. +2
4. +4
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11.
Oxygen has an oxidation number of -2 in
1. O2
2. NO2
3. Na2 O2
4. OF2
16.
Given the equations A, B, C, and D:
(A) AgNO3 + NaCl → AgCl + NaNO3
(B) Cl2 + H2 O → HClO + HCl
(C) CuO + CO → CO2 + Cu
(D) NaOH + HCl → NaCl + H2 O
-------------12.
What is the oxidation number of chromium in K2 Cr2 O7 ?
1. +12
3. +3
2. +2
4. +6
Which two equations represent redox reactions?
1. A and B
2. B and C
3. C and A
4. D and B
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-------------17.
13.
In which substance is the oxidation number of Cl equal to +1?
1. Cl2
3. AlCl3
2. Cl2 O
4. HClO2
In the reaction Cu + 2Ag + → Cu 2+ + 2Ag, the oxidizing agent is
1. Cu
3. Ag +
2. Cu 2+
4. Ag
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-------------14.
In which substance does hydrogen have an oxidation number
of zero?
1. LiH
3. H2 S
2. H2 O
4. H2
18.
Given the reaction: 2Na(s) + 2H2 O(l) → 2NaOH(aq) + H2 (g)
Which substance undergoes oxidation?
1. Na
3. H2
2. NaOH
4. H2 O
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-------------15.
Given the redox reaction: Co(s) + PbCl2 (aq) → CoCl2 (aq) +
Pb(s)
Which statement correctly describes the oxidation and
reduction that occur?
-
1. Co(s) is oxidized, and Cl (aq) is reduced.
2+
2. Co(s) is oxidized, and Pb (aq) is reduced.
3. Co(s) is reduced, and Cl-(aq) is oxidized.
19.
Which half-reaction correctly represents a reduction reaction?
1. Sn 0 + 2e- → Sn 2+
2. Na0 + e- → Na+
3. Li0 + e- → Li+
4. Br2 0 + 2e- → 2Br--------------
4. Co(s) is reduced, and Pb 2+(aq) is oxidized.
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20.
+
-
Given the reaction: 2Na + 2H2 O → 2Na + 2OH + H2
Which substance is oxidized?
25.
Which half-reaction correctly represents reduction?
1. Fe2+ + 2e- → Fe0
1. H2
3. Na
2. Fe2+ + e- → Fe3+
2. H+
4. Na+
3. Fe0 + 2e- → Fe2+
4. Fe0 + e- → Fe3+
-------------21.
Which equation represents a redox reaction?
1. 2Na+ + S2− → Na2 S
2. H+ + C2 H3 O2 → HC2 H3 O2
3. NH3 + H+ + Cl− → NH4 + + Cl−
-------------26.
In the reaction: 2H2 (g) + O2 (g) → 2H2 O(g), the oxidizing agent
is
1. H2
2. O2
3. H−
4. Cu + 2Ag + + 2NO3 − → 2Ag + Cu 2+ + 2NO3 −
4. O2−
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-------------22.
Which change occurs when an Sn 2+ ion is oxidized?
1. two electrons are lost
2. two electrons are gained
3. two protons are lost
4. two protons are gained
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27.
Given the reaction: Zn(s) + Cu 2+(aq) → Zn 2+(aq) + Cu(s)
Which particles must be transferred from one reactant to the
other reactant?
1. ions
3. protons
2. neutrons
4. electrons
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23.
Given the redox reaction: Ni + Sn 4+ → Ni2+ + Sn 2+
Which species has been oxidized?
28.
Which redox equation is correctly balanced?
1. Ni
3. Ni2+
1. Cr3+ + Mg → Cr + Mg 2+
2. Sn 4+
4. Sn 2+
2. Al3+ + K → Al + K+
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24.
In the reaction: 2H2 S + 3O2 → 2SO2 + 2H2 O, the oxidizing
agent is
1. oxygen
3. sulfur dioxide
2. water
4. hydrogen sulfide
--------------
3. Sn 4+ + H2 → Sn + 2H+
4. Br2 + Hg → Hg 2+ + 2Br-------------29.
Oxidation-reduction reactions occur because of the competition
between particles for
1. neutrons
3. protons
2. electrons
4. positrons
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30.
35.
In the reaction: Zn + Fe
2+
→ Zn
2+
+ Fe, the reducing agent is
In the reaction: Pb + 2Ag + → Pb 2+ + 2Ag, the oxidizing agent is
1. Zn
3. Zn 2+
1. Ag +
3. Pb
2. Fe2+
4. Fe
2. Ag
4. Pb 2+
--------------
--------------
31.
2+
3+
In the reaction: 2Al(s) + 3Cu (aq) → 2Al (aq) + 3Cu(s), the
Al(s)
1. gains protons
3. gains electrons
2. loses protons
4. loses electrons
36.
In the reaction: 2Mg + O2 → 2MgO, the magnesium is the
1.
2.
3.
4.
--------------
oxidizing agent and is reduced
oxidizing agent and is oxidized
reducing agent and is reduced
reducing agent and is oxidized
--------------
32.
37.
+
2+
+
In the reaction: Pb + 2Ag → Pb + 2Ag, the Ag is
1. reduced, and the oxidation number changes from +1 to
0
2. reduced, and the oxidation number changes from +2 to
0
3. oxidized, and the oxidation number changes from 0 to
+1
4. oxidized, and the oxidation number changes from +1 to
0
-------------33.
Which half-reaction correctly represents oxidation?
1. Mg + 2e- → Mg 2+
2. Mg 2+ + 2e- → Mg
3. Mg 2+ → Mg + 2e4. Mg → Mg 2+ + 2e-------------34.
In the reaction: 2Fe3+(aq) + 2I−(aq) → 2Fe2+(aq) + I2 (s), the
oxidizing agent is
1. Fe2+(aq)
The diagram represents a voltaic cell. Which statement correctly
describes the direction of flow for the ions in this cell when the
switch is closed?
1. Ions move through the salt bridge from B to C, only.
2. Ions move through the salt bridge from C to B, only.
3. Ions move through the salt bridge in both directions.
4. Ions do not move through the salt bridge in either
direction.
--------------
2. Fe3+(aq)
3.
4.
Figure 1
I−(aq)
I2 (s)
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42.
38.
[Refer to figure 1 in question 37]
The diagram represents a voltaic cell. When the switch is
closed, which group of letters correctly represents the
direction of electron flow?
1. A → B → C → D
2. A → F → E → D
3. D → C → B → A
4. D → F → E → A
-------------39.
Which species acts as the anode when the reaction Zn(s) +
Pb 2 +(aq) → Zn 2+(aq) + Pb(s) occurs in an electrochemical
cell?
1. Zn(s)
2. Zn 2+(aq)
Figure 2
The diagram represents a chemical cell at 298 K and 1
atmosphere. Which species represents the cathode?
3. Pb 2+(aq)
4. Pb(s)
-------------40.
The type of reaction in a voltaic cell is best described as a
1. spontaneous oxidation reaction, only
2. nonspontaneous oxidation reaction, only
3. spontaneous oxidation-reduction reaction
4. nonspontaneous oxidation-reduction reaction
-------------41.
The purpose of a salt bridge in a voltaic cell is to
1. allow for the flow of molecules between the solutions
2. allow for the flow of ions between the solutions
3. prevent the flow of molecules between the solutions
4. prevent the flow of ions between the solutions
1. Zn
3. Cu
2. Zn 2+
4. Cu 2+
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43.
Which type of chemical reaction generates the electrical energy
produced by a battery?
1. oxidation-reduction
3. neutralization
2. substitution
4. addition
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Answer Key for Electrochemistry Basics
1. 2
16. 2
31. 4
2. 1
17. 3
32. 1
3. 4
18. 1
33. 4
4. 3
19. 4
34. 2
5. 1
20. 3
35. 1
6. 2
21. 4
36. 4
7. 3
22. 1
37. 3
8. 4
23. 1
38. 2
9. 4
24. 1
39. 1
10. 4
25. 1
40. 3
11. 2
26. 2
41. 2
12. 4
27. 4
42. 3
13. 2
28. 4
43. 1
14. 4
29. 2
15. 2
30. 1
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