A. Very Short-Answer Questions
1. What is electrochemistry?
2. Redox reaction involve the transfer of electrons, yet there is no flow of current. Why is this so?
3. How is the flow of electric current in a metal wire different from that in a solution of an electrolyte?
4. What are electrodes?
5. What is galvanic cell?
6. Is the reaction occurs in a galvanic cell spontaneous or nonspontaneous?
7. What is an anode?
8. Which electrode, cathode or anode is the positive pole in a galvanic cell?
9. How much is 1 faraday of charge?
10. Write the cell reaction of the Daniell cell for the passage of 1 faraday of charge.
11. How much of moles of Cu is deposited on the cathode for the passage of 965 C of charge in a Daniell cell?
12. What is the standard emf?
13. In the hydrogen-oxygen galvanic cell, which electrode is the anode?
14. What is the reversible cell?
15. Write the line notation of the Daniell cell.
16. Write the cell diagram for the cell reaction Mg + ZnSO4 → MgSO4 + Zn.
17. How is the equilibrium constant of a reversible cell reaction related to the standard emf of the cell?
18. What is standard hydrogen electode?
19. In a table of reduction potentials, the electrode potentials decreases as one goes up. Where are the strongest reducing agents- at the bottom or at the top? Are they at the left or the right of the half-reactions?
20. What is a concentration cell?
21. What is electrolysis?
22. Why is a CaCl2 + NaCl mixture taken for the electrolysis of molten NaCl?
23. Why does water need to be made alkaline or acidic to carry out electrolysis?
24. The electrolysis of aqueous AgNO3does not evolve H2 gas at the cathode. Why?
25. How is the eqivalent weight of KMnO4 related to its formula weight in the change
MnO4- → Mn2+?
26. How many coulombs of charge is required for the deposition of 1 mole of Al in the electrolysis of molten Al2O3?
27. What is conductivity?
28. What is molar conductivity?
29. How is equivalent conductivity of Fe2(SO4)3related to its molar conductivity?
B. Short-Answer Questions
1. What are differences between a chemical and electrochemical reaction?
2. What is a salt bridge?
3. The standard hydrogen-oxygen cell (E0cell=1.23V) and standard Daniell cell (EOcell = 1.10V) are connected in parallel. What are the cell reaction in the two cell?
4. What is electrode potentials?
5. How is the emf of a cell related to the electrode potentials?
6. What are oxidation and reduction potentials?
7. How can be the standard potential of an electrode be determined?
8. Cs has a lower ionization than Li, showing a stronger tendency to get oxidized to Cs+. Why then is the oxidation potential of Cs lower than that of Li?
9. A chemistry textbook says, “An oxidant will spontaneously oxidize a reductant placed lower than it in the table of reduction potentials”. Do you expect to find the half-reaction
Li+ + e- → Li at the lower end or the higher end of the table in the book?
10. How is the electrode potential of a hydrogen related to the pH of the electrolyte solution?
11. What are primary and secondary cells? Give examples of each.
12. What are fuel cell? How they are different from ordinary galvanic cells?
13. What is corrosion?
14. Why do Al and Zn not corrode when exposed to air though they are more reactive than Fe?
15. Explain the corrosion of iron on exposure to air.
16. Why does iron corrode more easily in soda water than ordinary water?
17. What are the different methods of preventing the rusting of iron?
18. What are different types of reaction possible in electrolysis?
19. Why does lead not evolve H2gas with HCI or H2SO4 solution although the reduction potential of Pb2+ + 2e- → Pb is < 0?
20. What is decomposition voltage?
21. How is the electrolysis of an aqueous solution of NaCI different from the electrolysis of molten NaCI?
22. Why does H2 gas evolve at the cathode in the electrolysis of an aqueous solution of NaCI with platinum cathodes?
23. Why does O2 gas evolve at the anode in the electrolysis of a dilute aqueous solution of NaCI, but CI2evolve in that of a concentrated solution of NaCI?
24. H2 does not evolve if Hg is used as the cathode in the electrolysis of aqueous NaCI. Explain.
25. How does the electrolysis of aqueous AgNO3change with change in electrodes from Pt to Ag?
26. What are Faraday’s law of electrolysis?
27. Why do electron not conduct electricity in an aqueous solution?
28. What are electrolytic conductors?
29. What is the cell constant? How is the cell constant of a conductance cell usually determined?
30. What are different units of conductivity and molar conductivity?
31. How does the conductivity of an electrolyte change with concentration?
32. Why does the conductivity of an electrolyte decrease after reaching a peak as concentration increases?
33. What is molar conductance at infinite dilution? How is it determined for strong electrolytes?
34. Why is it not possible to determine the molar conductivity at infinite dilution of a weak electrolyte the same way as that of a strong electrolyte?
35. What is Kohlrausch’s law of independent migration of ions? Explain with examples.
36. How can the molar conductivity at infinite dilution (of electrolytes) be determined applying the law of independent migration of ions?
C. Long-Answer Questions
1. Write cell diagram for the following cell reactions. In each case write the electrode reactions
(a) Mg(s) + 2Ag+(aq) → Mg2+(aq) + 2Ag(s)
(b) Cd(s) + CI2(g) → Cd2+(aq) + 2CI-(aq)
(c) H2(g) + Br2(I) → 2H+(aq) + 2Br-(aq)
2. What is E0cell for the following cells?
(i) Zn I Zn2+ II Sn2+ I Sn
(ii) Ni I Ni2+ II Cu2+ I Cu
Also, write the cell reaction for each cell.
3. Use the data and predict whether the following skeleton equations represent spontaneous reactions. Complete and balance the spontaneous reactions.
(i) Ag+ + Fe2+ → Ag + Fe3+
(ii) H2O2 + Ag+ → Ag + O2
(iii) PbO2 + CI- → Pb2+ + CI2
(iv) I- + NO3- → I2 + NO
4. Indicate whether the following half cells would behave as anodes or cathodes of the galvanic cells formed with a standard hydrogen electrode.
(i) PbIPb2+ (1.00 M)
(ii) PtIFe3+ (0.010 M), Fe2+(0.010 M)
(iii) SnISn2+ (1.0x10-4 M)
(iv) AgIAgBr (satd.) Br-(1.00 M)
5. Indicate the direction of the following reactions. Unless specified otherwise, assume that all substances in solution are initially at a concentration of 1.00 M.
(i) Sn4+ + 2Fe2+ → Sn2+ + 2Fe3+
(ii) Sn2+ + Pb → Sn + Pb2+
(iii) Sn2+(0.01 M) + Pb → Sn + Pb2+(0.0001)
(iv) 4Co3+ + 2H2O → 4Co2+ + O2 + 4H+
Hiç yorum yok:
Yorum Gönder