1. In an electrolytic cell the electrode at which
the electrons enter the solution is called the
______ ; the chemical change that occurs at this
electrode is called _______.
(a) anode, oxidation
(b) anode, reduction
(c) cathode, oxidation
(d) cathode, reduction
(e) cannot tell unless we know the species being
oxidized and reduced.
2. Which of the following statements is FALSE?
(a) Oxidation and reduction half-reactions occur
at electrodes in electrochemical cells.
(b) All electrochemical reactions involve the
transfer of electrons.
(c) Reduction occurs at the cathode.
(d) Oxidation occurs at the anode.
(e) All voltaic (galvanic) cells involve the use of
electricity to initiate nonspontaneous chemical
reactions.
3. The half-reaction that occurs at the anode
during the electrolysis of molten sodium
bromide is:
(a) 2 Br- Br2 + 2 e-
(b) Br2 + 2 e- 2 Br-
(c) Na+ + e- Na
(d) Na Na+ + e-
(e) 2 H2O + 2 e- 2 OH- + H2
4. During the electrolysis of aqueous KCl
solution using inert electrodes, gaseous
hydrogen is evolved at one electrode and
gaseous chlorine at the other electrode. The
solution around the electrode at which hydrogen
gas is evolved becomes basic as the electrolysis
proceeds. Which of the following responses
describe or are applicable to the cathode and
the reaction that occurs at the cathode?
(1) the positive electrode
(2) the negative electrode
(3) 2 Cl- Cl2 + 2 e-
(4) Cl2 + 2 e- 2 Cl-
(5) 2 H2O O2 + 4 H+ + 4
e-
(6) 2 H2O + 2 e- H2 + 2
OH-
(7) electrons flow from
the electrode to the
external circuit
(8) electrons flow into the
electrode from the
external circuit
(9) oxidation
(10) reduction
(a) 2, 6, 8, 9
(b) 1, 5, 7, 9
(c) 2, 5, 7, 9
(d) 1, 6, 8, 10
(e) 2, 6, 8, 10
5. What mass (in grams) of nickel could be
electroplated from a solution of nickel(II)
chloride by a current of 0.25 amperes flowing for
10 hours?
(a) 12 g
(b) 5.5 g
(c) 0.046 g
(d) 2.7 g
(e) 6.0 g
6. Molten AlCl3 is electrolyzed for 5.0 hours with
a current of 0.40 amperes. Metallic aluminum is
produced at one electrode and chlorine gas, Cl2,
is produced at the other. How many liters of Cl2
measured at STP are produced when the
electrode efficiency is only 65%?
(a) 0.55 L
(b) 0.63 L
(c) 0.84 L
(d) 0.98 L
(e) 1.02 L
7. How long (in hours) must a current of 5.0
amperes be maintained to electroplate 60 g of
calcium from molten CaCl2?
(a) 27 hours
(b) 8.3 hours
(c) 11 hours
(d) 16 hours
(e) 5.9 hours
8. How long, in hours, would be required for the
electroplating of 78 g of platinum from a solution
of [PtCl6]2-, using an average current of 10
amperes at an 80% electrode efficiency?
(a) 8.4
(b) 5.4
(c) 16.8
(d) 11.2
(e) 12.4
