UNIT-I ELECTROCHEMISTRY PART-A

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1 UNIT-I ELECTROCHEMISTRY PART-A 1. What is electrochemistry? 2. What do you understand by electrode potential? 3. Define E.M.F of an electrochemical cell? 4. Define (a) Single electrode potential (b) Standard electrode potential 5. What are concentration cells? 6. What are batteries? 7. Differentiate between a galvanic cell and an electrolytic cell. Give example 8. What are the applications of batteries? 9. Define fuel cell? 10. What are electrochemical sensors? Give its limitations. 11. What is an electrochemical cell? 12. How corrosion is different from erosion? 13. What are the disadvantages of corrosion? 14. What are anodic coatings? 15. What happens when cathode coating breaks? 16. What is corrosion? 17. How fuel cell is different from battery? What are the advantages? 18. What is salt bridge? Explain the role of salt bridge in galvanic cell? 19. What are the difference between primary battery and secondary battery? 20. Define Storage Cell. PART-B 1. Define the standards electrode potential. What are its applications? 2. A) Write a note on Concentration cells with suitable examples? B) Explain Nickel-Cadmium batteries? 3. Define batteries? Explain in detail about lithium ion batteries? 4. Write a note on A) Lead acid battery B) Lithium-Manganese oxide batteries? 5. Describe about A) Methanol-Oxygen fuel cell B) Hydrogen-Oxygen fuel cell 6. Write a note on A) Potentiometric Sensors. With examples B) Voltammetric Sensors. With examples 7. Define corrosion of metals and explain the mechanism of electrochemical corrosion? 8. Explain various factors influence on corrosion of metals? 9. Explain Oxidation corrosion? 10. Explain the following A) Nickel electroplating B) Electro less plating 11. Explain A) Sacrificial anodic protection B) Impressed current Cathodic protection 12. A) Difference between chemical and electrochemical corrosion? B) Explain differential aeration corrosion? Department of Chemistry Page 1

2 Note: 1) Answer all the questions 2) Write all the Answers in CAPITALS only 1. A galvanic cell converts [ ] A) Electrical energy into Chemical energy B) Chemical energy into Electrical energy C) Electrical energy into Heat energy D) Chemical energy into Heat energy 2. In electrochemical series elements are arranged in the [ ] A) Increasing order of SRP B) Decreasing order of SRP C) Increasing order of Equivalent weights D) Increasing order of oxidation potentials 3. The potential of the standard hydrogen electrode is [ ] A) 1 volt B) 0 volt C) 10 volt D) 0.5 volt 4. The electrode potential is the tendency of metal [ ] A) To lose electrons B) To gain electrons C) Either lose or gain electrons D) none 5. The potential of two metal electrodes used in a cell are 0.35V and 0.25V. The EMF of the cell formed by connecting them is [ ] A) 0.5V B) 1.20V C) -0.5V D) None 6. In the cell: Cu/Cu 2+ //Ag + /Ag [ ] A) Oxidation undergoes at Cu B) Reduction undergoes at Cu C) Oxidation undergoes at Ag D) All 7. One of the most popular uses of galvanic cells are [ ] A) Battery B) Electrolyte preparation C) Potentiostat D) None 8. A storage cell is a device that can operate [ ] A) Both as Voltaic cell and Electrolytic cell B) Voltaic C) Electrolytic D) none 9. Which of the following is a primary cell [ ] A) Mercury battery B) Lithium battery C) Daniel cell D) NICAD 10. is a secondary cell or battery [ ] A) NICAD B) Daniel cell C) Voltaic cell D) Laclanche cell 11. The cathode of Ni-Cd battery is composed of [ ] A) Cadmium B) Nickel C) Paste of NiO(OH) D) Paste of Cd(OH) The cell reaction Zn + Cu 2+ Zn 2+ + Cu is represented as [ ] A) Cu/Cu 2+ //Zn/Zn 2+ B) Cu/Cu 2+ // Zn 2+ / Zn C) Zn/Zn 2 //Cu 2+ /Cu D) Zn/Zn 2+ // Cu/Cu If the oxidation potential of Zn metal is 0.76V, the E cell for the redox reaction Zn + 2H + (aq, 1M) Zn 2+ + H 2 (1atm) is [ ] A) 0.76 B) C) D) A fuel cell converts [ ] A) Chemical energy of fuel directly to electricity B) Chemical energy of fuel directly to Heat C) Chemical energy of fuel directly to Pressure D) None 15. In hydrogen-oxygen fuel cell, the electrodes are made of [ ] A) Al B) Fe C) Cd D) Graphite 16. When storage cell is operating as voltaic cell, it is said to be [ ] A) Charging B) Discharging C) Neutral D) None 17. In lead-acid storage cell, during discharging operation the concentration of H 2 SO 4 [ ] A) Increases B) Decreases C) Both D) None 18. Which of the following is proton exchange fuel cell [ ] A) H 2 -O 2 B) Methanol C) Phosphoric acid D) All 19. Hydrogen-Oxygen fuel cells are used as auxillary energy source in [ ] A) Trains B) Aeroplanes C) Space vehicle D) Automobile engine Department of Chemistry Page 2

3 20. The difference of potential which causes the flow of electron from one electrode to another electrode is called [ ] A) Oxidation B) Reduction C) Neutralization D) Electromotive force 21. What is the voltage produced by H 2 -O 2 fuel cell, operating under standard conditions [ ] A) 1.0 V B) 1.23V C) 2.0V D) 0.5V 22. When iron/zinc is added to CuSO 4 solution, copper is precipitated, it is due to [ ] A) Oxidation of Cu 2+ B) Hydrolysis of CuSO 4 C) Ionization of CuSO 4 D) Reduction of Cu The tendency of an electrode to lose or gain electrons, when it is contact with its own ions is called [ ] A) Hydration B) Oxidation C) Reduction D) Electrode Potential 24. When does a cell formulation represent a non-spontaneous activity of galvanic cell [ ] A) EMF is Negative B) EMF is Positive C) EMF is Zero D) None 25. Nernst equation is mainly useful to calculate [ ] A) Redox system B) EMF of cell C) Polarization D) None 26. The EMF of concentration cell decreases mainly due to [ ] A) Transfer of metallic ions from higher concentration to lower concentration B) Oxidation C) Reduction D) Can t explain 27. The main purpose of salt bridge in the voltaic cell is [ ] A) To maintain flow of electrons B) To maintain charge neutrality C) Barrier for electron transfer D) None 28. Corrosion is an example of [ ] A) Reduction B) Oxidation C) Electrolysis D) Erosion 29. The rusting of iron is catalysed by which of the following [ ] A) O 2 B) Zn C) H + D) Fe 30. The rate of corrosion of iron in atmosphere depends on [ ] A) Frequency of rainfall B) Humidity of air C) Intensity of atmosphere pollution D) All 31. Electrochemical corrosion can occur only when [ ] A) Air is in contact with metal B) Liquid medium is in contact with metal C) Oxygen is in contact with metal D) None 32. Chemical corrosion always takes place in [ ] A) Anodic and Cathodic area B) Anodic area C) Cathodic area D) Interior of metal 33. Which of the following metal oxide film is protective from corrosion [ ] A) Porous B) Non-porous C) Volatile D) Unstable 34. Which type of the metal oxide film causes rapid and continuous corrosion [ ] A) Non-porous and Adherent B) Stable and Non-porous C) Porous or Volatile D) None 35. Electrochemical corrosion in acidic environment is carried with [ ] A) O 2 evolution B) O 2 absorption C) H 2 evolution D) H 2 absorption 36. During galvanic corrosion, the most noble metal acts as [ ] A) Anode as well as Cathode B) Cathode C) Anode D) Both B & C 37. Iron corrodes faster than aluminium due to [ ] A) Al reacts with medium B) Al forms protective oxide film C) Al is lighter than Fe D) None 38. Impure metal corrodes faster than pure metal due to [ ] A) Homogeneity B) Heterogeneity C) Both D) None 39. When Zn and Cu alloy is placed in moisture environment, then undergo corrosion [ ] A) Cu B) Zn C) Zn-Cu D) None 40. In electrochemical corrosion, if the corrosion product is insoluble in the medium then the corrosion rate further [ ] A) Increase B) Decrease C) Both D) None 41. Which of the following is volatile oxidation corrosion product of a metal [ ] A) CuO B) Fe 2 O 3 C) MoO 3 D) PbO 42. If the corrosion product is volatile, then the rate of corrosion of base metal will be [ ] A) Decrease B) Increase C) Unchanged D) Not expected Department of Chemistry Page 3

4 43. The corrosive resistance of stainless steel is mainly due to passive nature of metal [ ] A) Zn B) Sn C) Cr D) Fe 44. The chemical formula of rust [ ] A) Fe 2 O 3 B) FeO C) Fe 2 O 3.xH 2 O D) Fe 2 O When Zn and Cu alloy is placed in moisture environment, corrosion occurs at [ ] A) Cu B) Zn C) Zn-Cu D) None 46. In which of the following electroplating is porous and non-adherent [ ] A) Ni B) Zn C) Cr D) Pt 47. is the cathodic inhibitor [ ] A) Chromates B) Tungstates C) Mercaptans D) Phosphates 48. Which of the following are anodic inhibitors [ ] A) Mercaptans B) Amines C) Heterocyclic Nitrogen Compounds D) Chromates 49. Common Sacrificial anodic metal sheet used in sacrificial anodic protection method is [ ] A) Mg B) Mn C) Fe D) Ti 50. In impressed current cathodic protection method [ ] A) A battery or rectifier is used B) A battery or rectifier is need not used C) A battery or an anode sheet (weak anode) can be used D) All 51. In electrochemical corrosion processes, corrosion takes place [ ] A) At the Cathode B) At the Anode C) At Cathode or Anode D) None 52. The buried pipeline is protected from corrosion by connecting to Mg. It is called [ ] A) Impressed voltage protection B) Sacrificial cathodic protection C) Sacrificial anodic protection D) Any of these 53. For the corrosion of iron which of the following factor is essential [ ] A) Presence of moisture B) Presence of Oxygen C) Presence of acid D) All 54. The principle of electroplating is [ ] A) Electrolysis B) oxidation C) Reduction D) Anodization 55. A metal will be easily corroded if it is [ ] A) Less acidic B) More acidic C) Less basic D) More basic 56. In lead-acid storage cell during charging operation the concentration of H 2 SO 4 [ ] A) Increase B) Decreases C) Both D) None 57. When storage cell is operating as electrolytic cell it is said to be [ ] A) Charging B) Discharging C) Both D) None 58. An electrochemical cell or several electrochemical cells connected in series, that can be used as a source of direct electric current at a constant voltage [ ] A) Voltaic cell B) Electrolytic cell C) Battery D) Metallic conductors 59. The standard reduction potential at 298K for Zn 2+, Cr 3+,H + and Fe 3+ are0.76v, -0.74V, -0.0V and 0.77V respectively. The strongest reducing agent among these [ ] A) H + B) Cr 3+ C) Zn 2+ D) Fe The standard potential of hydrogen electrode at 1 atm in 1M is [ ] A) 1V B) 10V C) 0.00V D) 100V 61. The potential of two metal electrodes used in a cell are 0.70V and 0.83V. The EMF of the cell formed by combining them is [ ] A) -0.17V B) 1.2V C) 0.17V D) 1.57V 62. An inhibitor when added in small quantities to queous corrosive environment [ ] A) Effectively decreases the corrosion of the metal B) Effectively increases the corrosion of the metal C) No effect on corrosion of metal D) Increases the corrosive nature of the environment 63. In electrochemical corrosion [ ] A) Anode undergoes oxidation B) Cathode undergoes oxidation C) Anode undergoes reduction D) Both Cathode and anode undergo oxidation 64. The corrosion will be rapid at A) ph = 7 B) ph > 5 C) ph < 7 D) None Department of Chemistry Page 4

5 65. which of the following electroplating is hard and adherent [ ] A) Zn B) Ni C) Cr D) Pt 66. In cathodic protection, iron article is made cathode by connecting it with [ ] B) Pt B) Sn C) Zn D) Ti 67. The EMF of Daniel cell is [ ] A) 1.5V B) 1.23V C) 1.1V D) 1V 68. Which is the lightest metal [ ] A) Sn B) Cr C) Mn D) Li 69. Calculate the standard EMF of Ni-Ag cell whose potentials are and 0.83V [ ] A) -1.08V B) -0.58V C) 1.08V D) 0.58V 70. Electrical energy is not stored in cell [ ] A) Primary cell B) Secondary cell C) Both D) Fuel cell 71. In the following metals, the most negative SRP metal is [ ] A) Zn B) Fe C) Li D) K 72. In voltaic cell, the chemical energy is converted into electrical energy, the process [ ] A) Charging B) Discharging C) Both D) None 73. is the voltage generated by the H 2 O 2 fuel cell under standard conditions [ ] A) 0.8V B) C) 1.0 D) All 74. Device that evaluate information of sample by measuring electrical parameter variations [ ] A) Electrochemical cells B) Potentiometer C) Electrochemical sensors D) None 75. Sensors which measure the difference of two potentials in volts [ ] A) Amperometric sensors B) Potentiometric sensors C) Chemiresistors D) All 76. Sensors works on basic principle of [ ] A) Ohm s law B) Pogendroff s principle C) Thermodynamics D) Kinematics 77. A closed electrochemical circuit is used for selective determination of [ ] A) Acidity B) Basicity C) ph D) concentration 78. In ion selective electrode the recognition of hydrogen ion is done by [ ] A) Ion selective electrode B) Glass electrode C) Standard electrode D) None 79. The mother of all ion selective electrode is [ ] A) Ion selective electrode B) Glass electrode C) Standard electrode D) None 80. Glass electrode is sensitive to ions [ ] A) H + ions B) OH - ions C) Cl - ions D) K + ions 81. ph sensors measures [ ] A) Acidity B) Alkalinity C) Both D) None 82. The species present in sample other than the species of interest are called [ ] A) Interference B) Inter-ionic C) Zwitter ions D) None 83. Glucose is electrically molecule [ ] A) Acidity B) Alkalinity C) Neutral D) Electropositive 84. In potentiometric sensors the measurement of H + ions in glucose is made possible by [ ] A) Enzymatic oxidation of glucose to gluconic acid B) Glucose is converted to Fructose C) D-Glucose is converted to L-glucose D) Glucose can be analysed as such Department of Chemistry Page 5