Redox       Quiz #5     Application of Cells               Answers

 

 

1.         The corrosion of iron can be prevented by attaching a piece of zinc to the iron

            because the

            A.        iron acts as an anode

            B.        zinc reduces more readily than iron

            C.        electrons flow from the zinc to the iron

            D.        iron ions form more readily than zinc ions

 

2.         An iron spoon is electroplated with copper. The equation representing the

            reduction reaction is

            A.        Cu2+(aq) + 2e- ® Cu(s)

            B.        Cu(s) ® Cu2+(aq) + 2e-

            C.        Fe2+(aq) + 2e- ® Fe(s)

            D.        Fe(s) ® Fe2+(aq) + 2e-

 

3.         In an operating zinc-copper electrochemical cell, the oxidizing agent

            A.        loses electrodes at the anode

            B.        loses electrons to the cations

            C.        gains electrodes at the cations

            D.        gains electrons  from the anions

 

4.         An example of electro refining is the

            A.        extraction of aluminum from bauxite

            B.        purification of lead from an impure anode

            C.        recovery of zinc from a zinc sulphide solution

            D.        production of chlorine from a sodium chloride solution

 

5.         Electroplating always involves the

            A.        oxidation of anions

            B.        reduction of cations

            C.        reduction at the anode

            D.        oxidation at the cathode

 

6.         Hydrogen and oxygen react to provide energy in a

            A.        dry cell

            B.        fuel cell

            C.        alkaline cell

            D.        lead-acid storage cell

 

 


7.         En electrolytic process is used to purify impure lead. The electrodes are

 

ANODE

CATHODE

A.

carbon

impure lead

B.

pure lead

carbon

C.

pure lead

impure lead

D.

impure lead

pure lead

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1.0 M CuSO4

 
 

 


8.         The half-reaction at the cathode is

            A.        Cu2+ + 2e- → Cu(s)

            B.        2SO42- → S2O82- + 2e-

            C.        H2O → ½ O2(g) + 2H+ + 2e-

            D.        2H2O + 2e-H2(g) + 2OH-

 

9.         In the electrolysis of molten PbBr2 with inert electrodes, the products at the anode

            and cathode are

                        Anode              Cathode

            A.        Br2                               H2

            B.        O2                                 Pb

               C.        Pb                                 Br2

            D.        Br2                               Pb

 

10.       Under which conditions could an electrochemical cell provide 0.93V?

                        Anode              Cathode

            A.        Cu                    Mg

            B.        Mg                   Cu

            C.        Ag                   Pb

            D.        Pb                    Ag

 

 

 

 

11.       The reduction reaction in the above electrochemical cell is

            A.        Pb2+   +   2e-        Pb

            B.        Pb      Pb2+   +   2e-

            C.        Ag+   +   e-        Ag

            D.        Ag      Ag+   +   e-

 

12.       An industrial process involving electrolysis is the reduction of

            A.        water forming oxygen gas

            B.        water forming hydrogen gas

            C.        sea water forming chlorine gas

            D.        sea water forming bromine liquid

 

13.       To plate a nickel coin with copper

            A.        the nickel coin must be the cathode

            B.        the cathode must be made of copper

            C.        the electrons must flow to the anode

            D.        the solution must contain nickel ions

 

14.       Which of the following ions can be reduced from an aqueous solution

            A.        Ba2+

            B.        Al3+

            C.        Sn2+

            D.        Na+

 

15.       The principal function of a fuel cell is to

            A.        produce fuel

            B.        electrolyze fuel

            C.        produce hydrogen

            D.        produce electricity

 

16.       If a piece of nickel is to be gold-plated using an electolytic process, which half-

            reaction occurs at the cathode?

            A.        Ni → Ni2+ + 2e-

            B.        Ni2+ + 2e- → Ni

            C.        Au → Au3+ + 3e-

            D.        Au3+ + 3e- → Au

 

17.       Consider the following redox reaction

            AS2O3 + 2NO3- + 2H2O + 2H+ → 2H3AsO4 + N2O3

            In this reaction, nitrogen

            A.        loses electrons and increases in oxidation number

            B.        gains electrons and increases in oxidation number

            C.        loses electrons and decreases in oxidation number

            D.        gains electrons and decreases in oxidation number

 

 

18.       In an electrochemical cell, the cathode

            A.        is reduced

            B.        loses mass

            C.        is the reducing agent

            D.        is the site of reduction

 

19.       When 1.0 M NaI is electrolyzed, bubbles of gas form on one electrode and a

            reddish-brown substance forms on the other. The half-reaction at the cathode is

            A.        2I- → I2 + 2e-

            B.        Na+ + e- → Na

            C.        H2O + ½ O2 + 2H+ + 2e-

            D.        2H2O +2e- → H2 + 2OH-

 

20.       Which of the following would prevent the corrosion of an iron nail?

            A.        Store the nail in acid.

            B.        Store the nail in dry air.

            C.        Store the nail in water.

            D.        Store the nail wrapped in nickel wire in a beaker of distilled water.

 

21.       A student brought an old key to the Chemistry Lab to plate it with copper. He set

            up a cell like the one in the following diagram:

1 M CuSO4

 
 

 

 

 

 

 

 

 

 

 

 

 

 

 


            Which of the following combinations should produce the best result?

                        Object 1                      Electron Flow                         Object 2

            A.        AC power supply        towards the key                       Ag

            B.        DC power supply       towards the key                     copper

            C.        DC power supply        from the key                             copper

            D.        voltmeter                     from the key                             Pt

 

22.       Which of the following occurs when a solution of NiF2 is electrolyzed using

            inert carbon electrodes?

            A.        The cathode dissolves.

            B.        Hydrogen gas is produced.

            C.        The pH of the solution decreases.

            D.        The Ni2+ concentration increases.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


23.       What is the cathode reaction for this cell?

            A.        Na+   +   e-   ®   Na

            B.        Br2    +   2e- +    ®   2Br- 

            C.        2Br-   ®    Br2  +   2e-

            D.        H2O    ®   1/2O2   +   2H+   +  2e-

 

24.       Which of the following best describes the movement of sodium ions and

            electrons as the cell operates?

                        Na+ Ion Movement      Electron Movement

            A.        towards the Cu            towards the Pt

            B.        towards the Cu            towards the Cu

            C.        towards the Pt             towards the Cu

            D.        towards the Pt                       towards the Pt

 

25.       What is the standard cell voltage?

            A.        -075 V

            B.        +0.62 V

            C.        +0.75 V

            D.        +1.43 V

 

26.       Which of the following is an example of corrosion?

            A.        iron spontaneously oxidizing

            B.        sulphur spontaneously oxidizing

            C.        iron reducing

            D.        sulphur non-spontaneously oxidizing

27.       Consider the following equation:       

            Co   +   SO42-    +   4H+         Co2+  +   H2SO3  +  H2O

            Which statement is correct?

            A.        The sulphur is oxidized and the cobalt is reduced.

            B.        The cobalt is oxidized and the sulphur is reduced.

            C.        The hydrogen is reduced and the cobalt is oxidized.

            D.        The hydrogen is reduced and the oxygen is oxidized.

 

28.       Which of the following occurs during the electrolysis of molten KCl?

            A.        Oxygen forms at the anode.

            B.        Potassium forms at the anode.

            C.        Chlorine forms at the cathode.

            D.        Potassium forms at the cathode.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


29.       The above cell is constructed in order to nickel plate an object. For best results,

            which of the following should be used for electrodes A and B?

                        Electrode A                 Electrode B

            A.        object                          pure nickel

            B.        pure nickel                 object

            C.        object                          any conductor

            D.        any conductor              object

 

30.       A student tries to use the above apparatus to nickel plate a zinc object.  What will

            happen if the student places the zinc object at A and the nickel electrode at B?

                        Electrode A                 Electrode B

            A.        Ni forms                      Ni dissolves

            B.        Zn dissolves                Zn forms

            C.        Zn dissolves                Ni forms

            D.        Bubbles form               Bubbles form