Name: 
 

Chemistry 12 - Unit 5 Quiz


True/False
Indicate whether the sentence or statement is true or false.
 

1. 
In a redox reaction, electrons are transferred from the reducing agent to the oxidizing agent.
 

2. 
Reduction is the gain of electrons and occurs at the anode of any cell.
 

3. 
Oxidation is the decrease in oxidation number and reduction is the increase in oxidation number.
 

4. 
For both electric and electrolytic cells, electrons flow from the anode to the cathode.
 

5. 
Inert electrodes are required for all electrolytic cells.
 

6. 
Galvanic cells are based on spontaneous redox reactions; electrolytic cells are based on nonspontaneous redox reactions.
 

7. 
The hydrogen half-cell at standard conditions is defined as the reference half-cell for assigning reduction potentials.
 

8. 
The cell potential is determined by adding the reduction potentials for the two half-cell reactions.
 

9. 
In a standard cell, a porous boundary allows ions to pass through while preventing immediate mixing of the solutions in each half-cell.
 

10. 
A standard hydrogen-cobalt cell has a cell potential of -0.28 V.
 

11. 
In a standard copper-lead cell, lead is the cathode and copper is the anode.
 

12. 
The power supply in an electrolytic cell must supply a potential difference at least equal to the absolute value of the calculated cell potential.
 

13. 
The charge transferred by a 1.5-A current in a time of 2.0 min is 3.0 C.
 

14. 
Metals are always plated at the cathode of a cell.
 

15. 
If we assume a constant current, twice the mass of a metal can be refined in twice the time.
 

16. 
Corrosion of a metal can be described as an electrochemical cell in which the metal is the anode.
 

17. 
Both tin and zinc plating work equally well in inhibiting the corrosion of iron.
 

18. 
Large galvanic cells are used to refine metals and to produce nonmetals like chlorine.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

19. 
A redox reaction involves
a.
a transfer of electrons from the oxidizing agent to the reducing agent.
b.
a transfer of electrons from the reducing agent to the oxidizing agent.
c.
either a reduction or an oxidation.
d.
a transfer of a proton between two chemical agents.
e.
a transfer of electrons through a porous barrier.
 

20. 
The metal molybdenum, Mo(s), reacts to form MoO2(s). The half-reaction equation that explains the change in oxidation state of molybdenum can be written as
a.
Mo(s) + 2 e- c12-u5_files/i0220000.jpg Mo2+(s)
b.
Mo(s) c12-u5_files/i0220001.jpg Mo2+(s) + 2 e-
c.
Mo4+(s) + 4 e- c12-u5_files/i0220002.jpg Mo(s)
d.
Mo2+(s) c12-u5_files/i0220003.jpg Mo4+(s) + 2 e-
e.
Mo(s) c12-u5_files/i0220004.jpg Mo4+(s) + 4 e-
 

21. 
During the process of photosynthesis,
6 CO2(g) + 6 H2O(g) c12-u5_files/i0230000.jpg C6H12O6(aq) + 6 O2(g)
a.
carbon in carbon dioxide is oxidized.
b.
hydrogen in water is reduced.
c.
oxygen in carbon dioxide and/or water is oxidized.
d.
oxygen in glucose is oxidized.
e.
carbon in glucose is oxidized.
 

22. 
When copper metal is immersed in aqueous silver nitrate, a spontaneous reaction is observed. This reaction is best explained by stating that
a.
copper(II) ions have a greater attraction for electrons than do silver ions.
b.
copper(II) ions have a lesser attraction for electrons than do copper atoms.
c.
silver ions have a greater attraction for electrons than do copper(II) ions.
d.
silver ions have a lesser attraction for electrons than do silver atoms.
e.
silver atoms have a lesser attraction for electrons than do copper atoms.
 

23. 
Rank the following solutions in order of strongest oxidizing agent to weakest oxidizing agent.
      1      sulfuric acid
      2      lithium hydroxide
      3      gold(III) fluoride
      4      chromium(II) nitrate
a.
2 3 1 4
b.
3 4 1 2
c.
2 4 1 3
d.
3 1 4 2
e.
1 2 3 4
 

24. 
Which of the following equations describes a redox reaction?
a.
HCOOH(aq) c12-u5_files/i0260000.jpg CO(g) + H2O(l)
b.
H+(aq) + OHc12-u5_files/i0260001.jpg(aq) c12-u5_files/i0260002.jpg H2O(l)
c.
Ag+(aq) + Clc12-u5_files/i0260003.jpg(aq) c12-u5_files/i0260004.jpg AgCl(s)
d.
HMnO4(aq) c12-u5_files/i0260005.jpg H+(aq) + MnO4c12-u5_files/i0260006.jpg(aq)
e.
C2H4(g) + 3 O2(g) c12-u5_files/i0260007.jpg 2 CO2(g) + 2 H2O(g)
 

25. 
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.
2 H+(aq) + 2 K+(aq) c12-u5_files/i0270000.jpg H2(g) + K(s)
b.
Sn2+(aq) + 2 NO3c12-u5_files/i0270001.jpg(aq) + 4 H+(aq) c12-u5_files/i0270002.jpg 2 NO2(g) + 2 H2O(l) + Sn4+(aq)
c.
SO42-(aq) + 4 H+(aq) + 2 Clc12-u5_files/i0270003.jpg(aq) c12-u5_files/i0270004.jpg H2SO3(aq) + H2O(l) + Cl2(g)
d.
Cl2(g) + Sn2+(aq) c12-u5_files/i0270005.jpg Clc12-u5_files/i0270006.jpg(aq) + Sn(s)
e.
SnSO4(s) c12-u5_files/i0270007.jpg Sn2+(aq) + SO42-(aq)
 

26. 
All galvanic and electrolytic cells require
a.
an external power supply.
b.
a voltmeter.
c.
one electrode and two electrolytes.
d.
two electrodes and one electrolyte.
e.
a porous barrier.
 

27. 
In a galvanic cell, the reduction potentials of two standard half-cells are +0.35 V and -1.13 V. The predicted cell potential of the galvanic cell constructed from these two half-cells is
a.
1.48 V.
b.
1.13 V.
c.
0.78 V.
d.
0.35 V.
e.
+0.13 V.
 

28. 
If we assume standard conditions, the minimum potential difference required to electrolyze a solution of nickel(II) sulfate is
a.
0.17 V.
b.
0.43 V.
c.
0.97 V.
d.
1.49 V.
e.
2.06 V.
 

29. 
When molten aluminum bromide is electrolyzed, the products are
 
at the cathode
at the anode
a
Al3+(l)
Br-(l)
b
H2(g)
Br2(g)
c
Al(s)
O2(g), H+(aq)
d
H2(g), OH-(aq)
O2(g), H+(aq)
e
Al(l)
Br2(g)
a.
a
b.
b
c.
c
d.
d
e.
e
 

30. 
Standard reduction potentials for half-cells are based on the strengths of
a.
oxidizing agents relative to hydrogen gas.
b.
oxidizing agents relative to hydrogen ions.
c.
reducing agents relative to hydrogen ions.
d.
reducing agents relative to a standard acidic
solution.
e.
reducing agents relative to an inert electrode.
 

31. 
In the plating of nickel from a nickel(II) ion solution, the mass of nickel obtained from the transfer of 0.250 mol of electrons is
a.
0.125 g.
b.
0.250 g.
c.
7.34 g.
d.
14.7 g.
e.
21.9 g.
 

32. 
How long does it take to produce 4.50 g of scandium metal in the electrolysis of molten scandium chloride using a current of 8.5 A?
a.
57 min
b.
19 min
c.
6.3 min
d.
1.1 min
e.
0.54 min.
 

33. 
The process of corrosion is most similar to the principle behind
a.
a simple decomposition reaction.
b.
a combustion reaction.
c.
an electric cell.
d.
an electrolytic cell.
e.
a metal plating circuit
 

34. 
Why does the use of salt on the roads in the winter promote the rusting of objects containing iron?
a.
Salt lowers the freezing point of water.
b.
Salt bonds to the iron objects.
c.
Salt contains sodium which is an active metal.
d.
Salt is an electrolyte which improves the charge transfer.
e.
Salt contains chlorine, which is a corrosive element.
 

35. 
Which one of the following metals would be most likely to oxidize if a clean surface of the metal were exposed to the atmosphere?
a.
aluminum
b.
iron
c.
silver
d.
zinc
e.
gold.
 

36. 
A sacrificial anode for the protection of iron is
a.
a metal less easily oxidized than iron.
b.
a metal more easily oxidized than iron.
c.
any substance that is connected to an anode of a battery.
d.
an inert electrode.
e.
a metal that does not corrode.
 



 
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