Important Questions of Electrochemistry Chemistry | Zigya

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11.

The Gibbs energy for the decomposition of Al2O3 at 500°C is as follows
2 over 3 space Al subscript 2 straight O subscript 3 space rightwards arrow space 4 over 3 space Al space plus space straight O subscript 2 comma space increment subscript straight r space straight G space equals space plus 966 space kJ space mol to the power of negative 1 end exponent
The potential difference needed for electrolytic reduction of Al2O3 at 500°C is at least

  • 4.5 V

  • 3.0 V

  • 2.5 V

  • 2.5 V

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12.

Given,

straight E subscript Cl subscript 2 divided by Cl to the power of minus end subscript superscript 0 space equals 1.36 space comma
straight E subscript Cr to the power of 3 plus end exponent divided by Cr end subscript superscript 0 space equals space minus 0.74 space straight V
straight E subscript Cr subscript 2 straight O subscript 7 superscript 2 minus end superscript end subscript superscript 0 space equals space 1.33 space straight V comma
straight E subscript MnO subscript 4 superscript minus divided by Mn to the power of 2 plus end exponent end subscript superscript 0 space equals space 1.51 space straight V
Among the following, the strongest reducing agent is

  • Cr

  • Mn2+

  • Cr3+

  • Cr3+

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13.

Given: straight E subscript Fe to the power of 3 plus end exponent divided by Fe end subscript superscript 0 space equals space minus 0.036 straight V comma space straight E subscript Fe to the power of 2 plus end exponent divided by Fe end subscript superscript 0 space equals space minus 0.439 straight V The value of standard electrode potential for the change Fe subscript left parenthesis aq right parenthesis end subscript superscript 3 plus end superscript space plus space straight e to the power of minus space rightwards arrow Fe to the power of 2 plus end exponent space left parenthesis aq right parenthesis will be

  • -0.072

  • 0.385 V

  • 0.770 V

  • 0.770 V

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14.

On the basis of the following thermochemical data: (∆f G° H(aq)+=0)
H2O(l) → H+(aq) + OH(aq); ∆H =57.32kJ
H2(g) + 1/2O2(g) → H2O(l); ∆H = –286.20 kJ
The value of enthalpy of formation of OHion at 25°C is

  •  –22.88 kJ

  • –228.88 kJ

  • +228.88 kJ

  • +228.88 kJ

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15. Given space straight E subscript Cr to the power of 3 plus end exponent divided by Cr end subscript superscript straight o space equals space minus space 0.72 space straight V comma space straight E subscript Fe to the power of 2 plus end exponent divided by Fe end subscript superscript straight o space equals space minus space 0.42 space straight V. space The space potential space for space the space cell
Cr vertical line Cr to the power of 3 plus end exponent space left parenthesis 0.1 right parenthesis vertical line vertical line Fe to the power of 2 plus end exponent space left parenthesis 0.01 space straight M right parenthesis vertical line Fe space is
  • 0.26

  • 0.399

  • 0-399

  • 0-399

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16.

The cell, Zn|Zn2+ (1M)|| Cu2+ (1M|Cu(Eocell = 1.10 V), was allowed to be completely discharged at 298 K. THe relative concentration of Zn2+ to Cu2+ open square brackets fraction numerator open parentheses Zn to the power of 2 plus end exponent close parentheses over denominator left parenthesis Cu to the power of 2 plus end exponent right parenthesis end fraction close square brackets space is

  • antilog (24.08)

  • 37.3

  • 1037.3

  • 1037.3

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17.

In a saturated solution of the sparingly soluble strong electrolyte AgIO3 (molecular mass = 283) the equilibrium which sets in is

AglO subscript 3 space left parenthesis straight s right parenthesis space rightwards harpoon over leftwards harpoon with space on top space Ag to the power of plus space left parenthesis aq right parenthesis space plus space IO subscript 3 to the power of minus space left parenthesis aq right parenthesis
If the solubility product constant Ksp of AgIO3 at a given temperature is 1.0 × 10-8, what is the mass of AgIO3 contained in 100 ml of its saturated solution

  • 28.3 × 10–2 g

  • 2.83 × 10–3 g

  • 1.0 × 10–7 g

  • 1.0 × 10–7 g

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18.

The equivalent conductances of two strong electrolytes at infinite dilution in H2O (where ions move freely through a solution) at 25°C are given below:
straight capital lambda subscript CH subscript 3 COONa end subscript superscript straight o space equals space 91.0 space straight S space cm squared divided by equiv
straight capital lambda subscript HCl superscript straight o space equals space 426.2 space cm squared divided by equiv
What additional information/quantity one needs to calculate Λ of an aqueous solution of acetic acid?

  • ∧° of NaCl

  • Λº of CH3COOH

  • The limiting equivalent conductance of straight H to the power of plus space left parenthesis straight capital lambda subscript straight H to the power of plus end subscript superscript straight o right parenthesis

  • The limiting equivalent conductance of straight H to the power of plus space left parenthesis straight capital lambda subscript straight H to the power of plus end subscript superscript straight o right parenthesis

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19.

The first and second dissociation constants of an acid H2A are 1.0 × 10–5 & 5.0 × 10–10 respectively. The overall dissociation constant of the acid will be

  • 5.0 × 10–5

  • 5.0 × 1015

  • 5.0 × 10–15

  • 5.0 × 10–15

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20.

The molar conductivities ∧oNaOAc and ∧o HCl at infinite dilution in water at 25o C are 91.0 and 426.2 S cm2 /mol respectively. To calculate ∧o HOAc, the additional value required is

  • oH2O

  • oKCl

  • oNaOH

  • oNaOH

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