Questions for discussion
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PHYSICAL CHEMISTRY CHAPTER 2 ELECTROCHEMISTRY QUESTIONS FOR DISCUSSION 1. The unit of ECE is a) gram coulomb b) ampere per second c) gram per coulomb d) ampere second 2. When 9.65 coulombs of electricity is passed through a solution of silver nitrate (atomic mass of Ag = 108.0 g mol– 1). The amount of silver deposited is a) 6.4 mg b) 10.8 mg c) 21.2 mg d) 16.2 mg 3. The quantity of electricity required to liberate 112 cm3 of Hydrogen at STP from acidified water is a) 1 faraday b) 965 coulombs c) 96500 coulomb d) 0.1 faraday 4. The unit of quantity of electricity is a) ampere b) ohm c) volt d) coulomb 5. An example of a salt that will not hydrolyse is a) CH3COOH b) CH3COONH4 c) KCl d) NH4Cl 6. The standard reduction potentials of Zn and Ag in aqueous solution at 298 K are Zn+2 + 2e–  Zn ; E0 = –0.76 V and Ag+ + e– Ag ; E0 = + 0.80 V.
Which of the following reactions take place? a) Zn(s) + Ag(s) → Zn+2(aq) + Ag+(aq) b) Zn+2(aq) + Ag+(aq) → Zn(s) + Ag(s) c) Zn(s) + 2Ag + (aq) → Zn+2 (aq) + 2Ag(s) d) Zn+2(aq) + 2Ag(s) → 2Ag+(aq) + Zn(s) 7. The pH value of gastric juice in human stomach is about 1.8 and in the small intestine it is about 7. 8. The pKa value of aspirin is 3. 5. Aspirin will be: a) Ionised in the stomach and almost unionized in the small intestine b) Ionised in the small intestine and almost unionized in the stomach c) Unionised in the small intestine and in the stomach d) Completely ionized in the small intestine and in the stomach
a) Pt | H2(g) , HCl(soln) || AgCl(s) | Ag b) Pt | H2(g) | KCl(soln) || AgCl(s) | Ag c) Ag | AgCl(s) | KCl(soln) || HCl(soln), H2(g) | Pt d) Pt | H2(g) | HCl(soln) || AgNO3(soln) | Ag
a) 22400 cm3 b) 112 cm3 c) 1.008 g d) 224 cm3 10. In a galvanic cell, the electrons flow from a) Anode to cathode through the external circuit b) Cathode to anode through the external circuit c) Anode to cathode through the solution d) Cathode to anode through the solution
a) 3.26 V b) –1.66 V c) +1.66 V d) –3.26 V 12. The hydrogen electrode is dipped in a solution of pH 3 at 250C. The potential would be a) 0.087 V b) 0.177 V c) –0.177 V d) 0.059 V 13. 20 ml of 0.5 N HCl and 35 ml of 0.1 N NaOH are mixed. The resulting solution will… a) be base b) be natural c) turn methyl orange red d) turn phenolphthalein solution pink 14. Corrosion of iron is essentially an electrochemical phenomenon where the cell reaction are… a) Fe is oxidised to Fe3+ and H2O is reduced to b) Fe is oxidised to Fe2+ and dissolved oxygen in water is reduced to OH c) Fe is oxidised to Fe2+ & H2O is reduced to O2 d) Fe is oxidised to Fe2+ & H2O is reduced to 15. The standard electrode potential is measure by…… a) voltmeter b) electrometer c) galvanometer d) pyrometer 16. Which of the following does not conduct electricity? a) solid NaCl b) fused NaCl c) copper d) brine solution 17. When a quantity of electricity is passed through CuSO4 solution, 0.16 g of copper gets deposited. If the same quantity of electricity is passed through acidulated water, then the volume of H2 liberated at STP will be a) 56 cm3 b) 4.0 cm3 c) 8.0 cm3 d) 604 cm3 18. Which one of the following condition will increase the voltage of the cell represented by the equation: 
a) increase in the dimension of Ag electrode b) increase in the dimensions of Cu electrode c) increase in the concentration of Ag+ ions d) increase in the concentration of Cu2+ ions
a) Cu2+ b) Zn2+ c) Na+ d) Ca2+ 20. Which of the following salts on being dissolved in water gives pH > 7 at 250C? a) KCN b) KNO3 c) NH4Cl d) NH4CN 21. Which of the following electrolytic solutions has the least specific conductance? a) 2 N b) 0.002 N c) 0.02 N d) 0.2 N 22. Hydrogen gas is not liberated when the following metal is added to dil HCl a) Mg b) Sn c) Ag d) Zn 23. 30 cc of  solutions are mixed and the volume was made up to 1 dm3. The pH of the resulting solution is
a) 1 b) 3 c) 8 d) 2 24. The standard electrode potential for the half cell reactions are: Zn++ + 2e– → Zn E0 = –0.76 V Fe++ + 2e– → Fe E0 = –0.44 V The E.M.F of the cell reaction: Fe++ + Zn → Zn++ + Fe is a) +1.20 V b) +0.32 V c) –0.32 V d) –1.20 V 25. In the electrolysis of acidulated water, it is desired to obtain 1.12 cc of Hydrogen per second under S.T.P. condition. The current to be passed is a) 19.3 Amp b) 0.965 Amp c) 1.93 Amp d) 9.65 Amp 26. The one which decreases with dilution is a) Specific conductance b) Equivalence conductance c) Molar conductance d) Conductance 27. E1, E2 and E3 are the emf values of the three galvanic cells respectively A)  B)  C)  . Then,
a) E3 > E2 > E1 b) E2 > E3 > E1 c) E1 > E3 > E2 d) E1 > E2 > E3 28. The standard emf of a galvanic cell involving 3 moles of electrons in its redox reaction is 0. 59 V. The equilibrium constant for the reaction of the cell is…….. a) 1020 b) 1025 c) 1030 d) 1015 29. 9.65 C of electric current is passed through fused anhydrous magnesium chloride. The magnesium metal thus obtained is completely converted into a Grignard reagent. The number of moles of Grignard reagent obtained a) 1 10–4 b) 5 10–4 c) 1 10–5 d) 5 10–5 30. E1, E2 and E3 are the emfs of the following three galvanic cells respectively: (i) Zn(s) | Zn2+ (0.1 M) || Cu2+ (1M) | Cu(s) (ii) Zn(s) | Zn2+ (1M) || Cu2+ (1M) | Cu(s) (iii) Zn(s) | Zn2+ (1M) || Cu2+ (0.1 M) | Cu(s) Which one of the following is true? a) E1 > E2 > E3 b) E2 > E1 > E3 c) E3 > E2 > E1 d) E3 > E1 > E2 31. The standard emf of a galvanic cell involving 2 moles of electrons in its redox reaction is 0. 59 V. The equilibrium constant for the redox reaction of the cell is a) 105 b) 1020 c) 1010 d) 10 32. 9.65 coulombs of electric current is passed through fused anhydrous MgCl2. The magnesium metal obtained is completely converted into a Grignard reagent. The number of moles of Grignard reagent obtained is a) 1 10– 4 b) 5 10– 4 c) 1 10–5 d) 5 10–5 33. EMF of a cell in terms of reduction potential of its left and right electrodes is a) 34. Conductivity (unit Siemen’s S) is directly proportional to area of the vessel and the concentration of the solution in it and is inversely proportional to the length of the vessel then the unit of the constant of proportionality is a) 35. The heat required to raise the temperature of body by 1K is called a) specific heat b) thermal capacity c) water equivalent d) none of these 36. When during electrolysis of a solution of AgNO3 9650 coulombs of charge pass through the electroplating bath, the mass of silver deposited on the cathode will be a) 1.08 g b) 10.8 g c) 21.6 g d) 108 g 37. For the redox reaction: Zn(s) + Cu2+ (0.1 M) → Zn2+ (1M) + Cu(s) taking place in a cell,  is 1.10 volt. Ecell for the cell will be 
a) 2.14 volt b) 1.80 volt c) 1.07 volt d) 0.82 volt 38. For a cell reaction involving a two-electron change, the standard e.m.f. of the cell is found to be 0.295 V at 250C. The equilibrium constant of the reaction at 250C will be a) 1 10–10 b) 29.5 10–2 c) 10 d) 1 1010 39. SRP of metals A, B & C are respectively +0.05 V, –3.0 and –1.2 V. Reducing powers are a) B > C > A b) A > B > C c) C > B > A d) A > C > B 40. Which one of the following substances has the highest proton affinity? a) H2O b) H2S c) NH3 d) PH3 41. When rain is accompanied by a thunderstorm, the collected rain water will have a pH value a) slightly lower than that of rain water without thunderstorm b) slightly higher than that when the thunderstorm is not there c) uninfluenced by occurrence of thunderstorm d) which depends on the amount of dust in air
a) 0.01 M Na2SO4 b) 0.015 M glucose c) 0.015 M urea d) 0.01 M KNO3 43. Consider the following E0 values   . Under standard conditions the potential for the reaction 
a) 1.68 V b) 0.63 V c) 0.91 V d) 1.40 V 44. The standard e.m.f of a cell, involving one electron change is found to be 0.591 V at 250C. The equilibrium constant of the reaction is (F = 96,500 C mol–1;8.314 JK–1mol–1) a) 1.0 101 b) 1.0 1030 c) 1.0 1010 d) 1.0 105 45. The limiting molar conductivities  for NaCl, KBr and KCl are 126, 152 and 150 S cm2
mol–1 respectively. The for NaBr is:
a) 128 S cm2 mol–1 b) 302 D cm2 mol–1 c) 278 S cm2 mol–1 d) 176 S cm2 mol–1 46. The  values for Cr, Mn, Fe and Co are –0.41, +1.57, +0.77 and +1.97 V respectively. For which one of these metals the change in oxidation state from +2 to +3 is easiest?
a) Cr b) Co c) Fe d) Mn 47. For a spontaneous reaction the ΔG, equilibrium constant (K) and E0cell will be respectively a) –ve, >1, +ve b) +ve, >1, –ve c) –ve, <1, –ve d) –ve, >1, –ve 48. The highest electrical conductivity of the following aqueous solutions is of a) 0.1 M acetic acid b) 0.1 M chloroacetic acid c) 0.1 M fluoroacetic acid d) 0.1 M difluoroacetic acid 49. Aluminium oxide may be electrolysed at 10000C to furnish aluminium metal (At. mass = 27 amu; 1 Faraday = 96,500 coulomb). The cathode reaction is  . To prepare 5.12 kg of aluminium metal by this method would require
a) 5.49 107C electricity b) 1.83 107 C c) 5.49 104 C d) 5.49 101 C
50. Calculate  using appropriate molar conductances of electrolytes listed above at infinite dilution at 250C
a) 517.2 b) 552.7 c) 390.7 d) 217.5 51. Of the following sets which one does not contain isoelectronic species? a) 52. The molar conductivities  at infinite dilution in water at 250C and 91.0 and 426.2 S cm2/mol respectively. To calculate  the additional value required is
a) 53. The ionic mobility of alkali metal ions in aqueous solution is maximum for a) Na+ b) K+ c) Rb+ d) Li+ 54. Resistance of conductivity cell filled with a solution of an electrolyte of concentration 0.1 M is 100 Ω. The conductivity of this solution is 1.29 S m– 1. Resistance of the same cell when filled with 0.2 M of the same solution is 520 Ω. The molar conductivity of 0.02 M solution of the electrolyte will be a) 12.4 10– 4 S m2 mol–1 b) 124 10– 4 S m2 mol–1 c) 1240 10– 4 S m2 mol–1 d) 1.24 10– 4 55. The equivalent conductances of two strong electrolytes at infinite dilution in H2O (where ions move freely through a solution) at 250C are given below:   What additional information/quality one needs to calculate of an aqueous solution of acetic acid?
a) c) a) 37.3 b) 1037..3 c) 9.65 104 d) antilog (24.08) 57. Given  The potential for the cell Cr | Cr3+(0.1 M) || Fe2+(0.01 M) | Fe+ is
a) –0.26 V b) 0.26 V c) 0.339 V d) –0.339 V 58. Given:  ,  . The value of standard electrode potential for the change,  will be:
a) 0.770 V b) –0.270 V c) –0.072 V d) 0.385 V 59. The Gibbs energy for decomposition of Al2O3 at 5000C is :  The potential difference needed for electrolytic reduction of Al2O3 at 5000C is at least
a) 3.0 V b) 2.5 V c) 5.0 V d) 4.5 V 60. The correct order of  values with negative sign for the four successive elements Cr, Mn, Fe and Co is
a) Cr > Fe > Mn > Co b) Fe > Mn < Cr > Co c) Cr > Mn > Fe > Co d) Mn > Cr > Fe > Co 61. The reduction potential of hydrogen half-cell will be negative if: a) p(H2) = 1 atm and [H+] = 1.0 M b) p(H2) = 2 atm and [H+] = 1.0 M c) p(H2) = 2 atm and [H+] = 2.0 M d) p(H2) = 1 atm and [H+] = 2.0 M
a) 139.5 b) 203 c) 279 d) 101.5 63. Cell reaction is spontaneous when: a) 64. Cu+(aq) is unstable in solution and undergoes simultaneous oxidation and reduction according to the reaction: 2Cu+(aq) ↔ Cu2+(aq) + Cu(s) choose correct E0 for above reaction if  & 
a) –0.38 V b) +0.49 V c) +0.38 V d) –0.19 V 65. Among the following groupings which represents the collection is isoelectronic species? a) 66. Standard electrode potentials are: Fe2+/Fe, E0 = –0.44 Fe3+/Fe2+ E0 = 0.77 Fe2+, Fe3+ and Fe block are kept together, then: a) Fe3+ increases b) Fe3+ decreases c) Fe2+/ Fe3+ remains unchanged d) Fe2+ decreases 67. In electrolysis of NaCl when Pt electrode is taken then H2 is liberated at cathode while with Hg cathode, a) Hg is more inert than Pt b) more voltage is required to reduce H+ at Hg than at Pt c) Na is dissolved in Hg while it does not dissolved in Pt d) concentration of H+ ions is larger
a) Zn act as oxidizing agent when react with HNO3 b) HNO3 is weaker acid then H2SO4 and HCl c) In electrochemical series Zn is above hydrogen d) a) 6.42 V b) 8.56 V c) 2.14 V d) 4.28 V Directory: doc doc -> Enterprise Network Management iPost: Implementing Continuous Risk Monitoring at the Department of State doc -> Concept stage doc -> Application for acem doc -> What programs are available? doc -> 100 Village Primary School Music Classrooms doc -> Observational Assessment of Teaching Practices Teaching Assessment Initiative Proposal Submitted to The Teachers for a New Era project doc -> Concept stage doc -> Traditional British values Download 230.37 Kb. Share with your friends:
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H2(g) + AgCl(s) 
b) 
c) 
d) 
b) 
c) 
d) 
b) 
c) 
d) 
b) 
c) 
d) 
of CH3COOK b) The limiting equivalent conductance of H+ 
was allowed to be completely discharged at 298 K. The relative concentration of Zn2+ to 
is negative b) 
b) 
c) 
d) 
is reduced in preference to H3O+
of O2, the minimum emf required to carry out an electrolysis of Al2O3 is (F = 96500 C mol– 1)