Chemistry Questions: Redox Reactions and Cell Potentials

1.What is the Eo for the reaction Cl2 + 2I- −−−−> 2Cl- + I2?

a)2.54 V

b)0.82 V

c)1.90 V

d)1.65 V

2.Find Eo for the reaction   4Fe2+ + O2 + 4H+ −−−−> 4Fe3+ + 2H2O

a)-1.85 V

b)-2.00 V

c)2.00 V

d)0.46 V

3.Find Eo for the reaction   2Fe3+ + Fe −−−−> 3Fe2+

a)1.21 V

b)-0.33 V

c) 0.33 V

d)-1.21 V

4.Find the standard reduction potential for the half-reaction:

X+ + é −−−−> X   given that Cu + 2X+ −−−−> Cu2+ + 2X  Eo = 0.46 V

a) 0.12 V

b)-0.12 V

c) 0.80 V

d)-0.80 V

5.For question (4), what does "X" represent?

a)Tin

b)Lead

c)Cobalt

d)Silver

6.The net reaction of the mercury cell is 

Zn + HgO + H2O −−−−> Zn(OH)2 + Hg

What substance is oxidized at the anode of this cell?

a)Zn

b)Hg

c)HgO

d)O

7.The overall reaction of the silver oxide battery, which is used in watches, may be written as 

Ag2O + Zn −−−−> 2Ag + ZnO.  The cathode of the battery is:

a)Ag

b)ZnO

c)Ag2O

d)Zn

8.The overall reaction of the NiCad battery, used in portable tools, can be written as: 

2NiO(OH) + Cd + 2H2O −−−−> 2Ni(OH)2 + Cd(OH)2  

The cathode of this battery is:

a)NiO(OH)

b)Cd

c)Ni(OH)2

d)Cd(OH)2 

9.Which statement about the silver battery is correct, if the net reaction is:  Ag2O + Zn −−−−> 2Ag + ZnO ?

a)The mass of the Ag2O electrode increases as the battery is used.

b)Ag2O is the anode.

c)The electrons flow from the Ag2O electrode to the Zn electrode through the wire.

d)The Zn electrode is the negative terminal of the battery.

10.Which of the following is the strongest oxidizing agent?

a)Zn2+

b)Cl-

c)Sn2+

d)Fe3+

11.Which of the following is the strongest reducing agent?

a)Li+

b)Zn

c)Sn

d)H2

12.Given the two reactions:

Sn4+ + 2Cl- −−−−> Sn2+ + Cl2 Eo = -1.21 V (1)

2Cr2+ + I3- −−−−> 2Cr3+ + 3I- Eo = 0.94 V (2)

Which reaction(s) is(are) spontaneous at standard conditions?

a)(1) and (2)

b)only (1)

c)only (2)

d)neither (1) nor (2)

13.Which one of the following species will react with Sn at standard state conditions?

a)S

b)Ag+

c)Cu

d)Zn2+

14.Which species will be oxidized by O2 at standard state conditions and 25oC?

a)Cu2+

b)MnO4-

c)I-

d)All of these

15.Which pair of ions will be most likely to react at standard state conditions?

a)MnO4- and Sn2+

b)Zn2+ and Cl-

c)I- and Cu

d)Fe3+ and Cu2+

16.What is the resulting voltage produced for a cell which is made with the following reactions?

Mg2+ + 2é −−−−>  Mg    (1)

Ag+ + é −−−−> Ag (2)

17. If a piece of copper metal is dipped into a solution containing Cr3+ ions, what will happen?  Explain using Eo values.

18. What will happen if an aluminium spoon is used to stir an Fe(NO3)2 solution?

19. What will happen if an iron spoon is used to stir an AlCl3 solution?

20. Can a solution of Fe2(SO4)3 1 M be stored in a container made of nickel metal?  Explain your answer.

21. A silver ring is dropped in a solution of Pb(NO3)2 for a certain period.  Will you find it intact?  Explain.

22. The standard reduction potential for the following reaction is–2.936 V.  

K+ + é −−−−> K

What is the reduction potential for:

a)K −−−−> K+ + é

b)3K+ + 3é −−−−> 3K

23. Consider the following metals:

Pb / Cu / Ni / Fe / Al / Zn / Mg

State which metals will react in each of the following solutions.

a)HCl

b)CuSO4

c)Fe2(NO3)3

d)Ca(NO3)2

24. Will there be a reaction is a magnesium strip is placed in a solution containing Ca2+ ions?

25. Can a solution of CrCl3 be stored in an aluminum container?

26. Which element in the second period of the periodic table is the best reductant?

27. Which halogen is the best oxidant?

28. In the following reaction:

2FeCl2 + SnCl4 −−−−> 2FeCl3 + SnCl2

a)Which particle is oxidised?

b) Which particle is reduced?

29. Using the following spontaneous reactions, classify the 3 metals involved (Cr, Sn, Al) according to increasing reductant properties.

a) 2Cr + 3Sn2+ −−−−> 2Cr3+ + 3Sn

b) Al + Cr3+ −−−−> Al3+ + Cr

30. What is the maximum potential difference that can be obtained from a cell which operates according to the following global reaction?

Cr + Au3+ −−−−> Cr3+ + Au