THE ANSWER OF VOLTAIC CELL QUIZ Part I

1.If the two half-cells below were combined, what would be the correct chemical equation to represent the spontaneous REDOX process?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
Answer : Cu2+ + H2 ==> 2H+ + Cu
2.If the two half-cells below were combined, what would be the voltage generated by the spontaneous REDOX process?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
Answer (+0.34V)
3.If the two half-cells below were combined, which cell would undergo reduction?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
Answer : Copper half-cell
4.If the two half-cells below were combined, what would be the expected products of the spontaneous chemical reaction?
Zn2+ + 2e- <====> Zn (-0.76V)
H+ + e- <====> 1/2 H2 (0.00V)
Answer : H2 and Zn2+
5.Which of the following statements is FALSE?
Answer : Metal can be used for salt bridge
6.The following REDOX reactions all have positive Ecell voltages.
Cl2 + 2Br- ==> Br2 + 2Cl-
Br2 + 2I- ==> I2 + 2Br-
Cl2 + 2I- ==> I2 + 2Cl-
Which is the correct order of strength of oxidizing agent, from weakest to strongest?
Answer : Iodine < Bromine < Chlorine
7.The standard reduction potential for Zn2+ + 2e- ==> Zn, is -0.76 V, and the standard reduction potential for Fe3+ + e- ==> Fe2+, is +0.77V. What is the Ecell for the reaction below?
2Fe3+ + Zn ==> Zn2+ + 2Fe2+
Answer (+1.53)
8.Iron rusts when it comes into contact with water and oxygen. The change that the iron undergoes can be summarized thus; Fe ==> Fe2+ + 2e-. When iron metal is coated with solid zinc in a process called galvanizing, the oxidation of iron is prevented even if the zinc coating does not completely cover the iron metal. Which of the following statements serves best to explain these observations?
Answer : Solid zinc metal is more easily oxidized than iron
9.In the spontaneous reduction of Copper (II) ions with Nickel metal to form Copper metal and Nickel (II) ions, what will happen to the Ecell value when the concentration of Copper (II) ions is increased?
Cu2+ + 2e- <====> Cu (+0.34V)
Ni2+ + 2e- <====> Ni (-0.25V)
Answer : Ecell will increase
10.If the two half-cells below were combined, into which cell do anions from the salt bridge flow?
Cu2+ + 2e- <====> Cu (+0.34V)
H+ + e- <====> 1/2 H2 (0.00V)
Answer : Hydrogen
11.What value of Ecell do you expect for Pb(s) → Pb2+ + 2e-
in 0.015 M Pb2+ solution? E0 = +0.13 V
Answer (E = 0.00V)
12.Reduction potential is ....
Answer : an intensive property
13.The standard hydrogen electrode is assigned a potential of ….
Answer : zero volts
14.Calculate the value of E0cell for a galvanic cell that contains the following half cells:
Cl2 + 2e- → 2Cl- (E0 = 1.36v)
Cu+ + e- → Cu (E0 = 0.52v)
Answer (E0cell = 0.84 volts)
15.In all electrochemical cells, the process that takes place at the anode is … and the process that takes place at the cathode is ….
Answer : oxidation, reduction