JEE Chemistry - Electrochemistry

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Question - 1

The standard free energy change for the reaction:
\(\mathrm{H}_{2}(\mathrm{~g})+2 \mathrm{AgCl}_{(\mathrm{s})} \longrightarrow 2 \mathrm{Ag}_{(\mathrm{s})}+2 \mathrm{H}^{+}(\mathrm{aq})+2 \mathrm{Cl}^{-}(aq) \)
\(is-10.26 \mathrm{kcal} \mathrm{mol}^{-1} \text{ at }25^{\circ} \mathrm{C}. A \) cell using above reaction is operated at 25oC under \(\mathrm{P}_{\mathrm{H}_{2}}=1 \mathrm{~atm},\left[\mathrm{H}^{+}\right]\) and [C1- ] = 0.1. Calculate e.m.f.of cell ____________ .

  • A 0.34
  • B 0.44
  • C 0.54
  • D 0.64

Question - 2

The e.m.f. of cell Zn \(\left|\mathrm{ZnSO}_{4}\right|\left|\mathrm{CuSO}_{4}\right| \mathrm{Cu} \text { at } 25^{\circ} \mathrm{C} \text { is } 0.03 \mathrm{~V}\) and the temperature coefficient of e.m.f. ie -1.4 x 10-4 V per degree. Calculate heat of reaction for the change taking place inside the cell ____________ .

  • A -11.84
  • B -12.84
  • C -13.84
  • D -14.84

Question - 3

EMF diagram for iron is given as:
\(\mathrm{E}^{\circ} (volts) \mathrm{FeO}_{4}{ }^{2-} \stackrel{+2.20}{\longrightarrow} \mathrm{Fe}^{3+} \stackrel{+0.77}{\longrightarrow} \mathrm{Fe}^{2+} \stackrel{-0.445}{\longrightarrow} \mathrm{Fe}^{0}(\mathrm{Fe}=+6) \quad(\mathrm{Fe}=+3) \quad(\mathrm{Fe}=+2) \quad(\mathrm{Fe}=+0) \text { Determine the value of } \mathrm{E}_{\mathrm{FeO}_{4}^{2-} / \mathrm{Fe}^{2+}}^{2+}\) ______________ .

  • A 1.74
  • B 1.84
  • C 1.94
  • D 1.64

Question - 4

Calculate the maximum work that can be obtained from the cell.
\(\mathrm{Zn}\left|\mathrm{Zn}^{2+}(1 \mathrm{M})\right|\left|\mathrm{Ag}^{+}(1 \mathrm{M})\right| \mathrm{Ag} \)
\(\text {Given that }\mathrm{E}_{\mathrm{Zn} / \mathrm{Zn}^{2+}}^{0}=0.76 \mathrm{~V} \text { and }\mathrm{E}_{\mathrm{Ag} / \mathrm{Ag}^{+}}^{0}=-0.80 \mathrm{~V}\)

  • A 101.08
  • B 401.08
  • C 201.08
  • D 301.08

Question - 5

\(\text{For the cell process } : \mathrm{Sn}(\mathrm{s})+\mathrm{Pb}^{+2} (aq) \longrightarrow \mathrm{Pb}(\mathrm{s})+\mathrm{Sn}^{+2} (aq) \text { Calculate ratio of } \mathrm{Pb}^{+2} to \mathrm{Sn}^{+2} \text { ion concentration for spontainity .} \)
\(Given \)
\(\mathrm{E}_{\mathrm{Sn}^{2+} / \mathrm{Sn}}^{0}=-0.136 \mathrm{~V} \)
\(\mathrm{E}_{\mathrm{Pb}^{2+} / \mathrm{Pb}}^{0}=-0.126 \mathrm{~V}\)

  • A 0.46
  • B 0.56
  • C 0.66
  • D 0.76

Question - 6

A galvanic cell is consisted of metallic zinc plate immersed in 0.1 M Zn(NO3)2 solution and a lead plate immersed in 0.02M Pb(NO3)2 solution. Calculate emf of the cell. Given :
\(\mathrm{E}_{\mathrm{Zn}^{2+} / \mathrm{Zn}}^{0}=-0.76 \mathrm{~V} \text { and } \mathrm{E}_{\mathrm{Pb}^{2+} / \mathrm{Pb}}^{0}=-0.13 \mathrm{~V}\)

  • A 0.31
  • B 0.41
  • C 0.51
  • D 0.61

Question - 7

Calculate the potential of the standard Iron-Cadmium cell after the reaction has proceeded to 80% completion. Initially 1M of each taken and Eo for cell = 0.04 V.
\(\mathrm{Fe}(\mathrm{s})\left|\mathrm{Fe}^{+2}\right|\left|\mathrm{Cd}^{+2}\right| \mathrm{Cd}\)

  • A 0.01
  • B 0.02
  • C 0.03
  • D 0.04

Question - 8

The e.m.f. of the cell, H2(g) |Buffer| Normal calomel electrode is 0.6885 volt at 25oC when barometric pressure is 760 mm Hg. What is pH of the buffer solution.\(\mathrm{E}^{\mathrm{o}} \text { calomel }=0.28 \mathrm{volt}\)

  • A 5.91
  • B 6.91
  • C 7.91
  • D 8.91

Question - 9

A 200 W, 110V incandescent lamp is connected in series with an electrolytic cell of negligible resistance containing a solution of ZnCl2. What weight of Zn will be deposited from the solution on passing current for 30 minutes? \(\text { (At.wt. of } \mathrm{Zn}=65.4 \text { ) }\)

  • A 1.06
  • B 1.30
  • C 1.20
  • D 1.10

Question - 10

All the energy released from the reaction \(\mathrm{X} \rightarrow \mathrm{Y}, \Delta \mathrm{r} \mathrm{G}^{\circ}=-193 \mathrm{~kJ} \mathrm{~mol}^{-}\) is used for oxidizing \(\mathrm{M}^{+} \text {as } \mathrm{M}^{+} \rightarrow \mathrm{M}^{3+}+2 \mathrm{e}^{-}, \mathrm{E}^{\circ}=-0.25 \mathrm{~V}\). Under standard conditions, the number of moles of M+ oxidized when one mole of X is converted. io Y is \(\left[\mathrm{F}=96500 \mathrm{C} \mathrm{mol}^{-1}\right]\)

  • A 3.00
  • B 2.00
  • C 4.00
  • D 6.00
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