Electrochemistry

For the reduction of silver ions with copper metal, the standard cell potential was found to be +0.46 V at 25 C. The value of standard Gibbs energy, G will be (F = 96500 C mol-1)

1. -89.0 kJ
2. -89.0 J
3. -44.5 kJ
4. -98.0 kJ

An increase in equivalent conductance of a strong electrolyte with dilution is mainly due to

1. increase in ionic mobility of ions
2. 100% ionisation of electrolyte at normal dilution
3. increase in both i.e., number of ions and ionic mobility of ions
4. increase in number of ions.

Given : (i) Cu2+ + 2e- Cu, E = 0.337 V (ii) Cu2+ + e- Cu+, E = 0.153 V Electrode potential, E for the reaction, Cu+ + e- Cu, will be

1. 0.90 V
2. 0.30 V
3. 0.38 V
4. 0.52 V

Al2O3 is reduced by electrolysis at low potentials and high currents. If 4.0 104 amperes of current is passed through molten Al2O3 for 6 hours, what mass of aluminium is produced? (Assume 100% current efficiency, at. mass of Al = 27 g mol-1).

1. 8.1 104 g
2. 2.4 105 g
3. 1.3 104 g
4. 9.0 103 g

The equivalent conductance of M/32 solution of a weak monobasic acid is 8.0 mho cm2 and at infinite dilution is 400 mho cm2. The dissociation constant of this acid is

1. 1.25 10-6
2. 6.25 10-4
3. 1.25 10-4
4. 1.25 10-5

On the basis of the following E values, the strongest oxidizing agent is [Fe(CN)6]4- [Fe(CN)6]3- + e-; E = -0.35 V Fe2+ Fe3+ + e-; E = -0.77 V

1. Fe3+
2. [Fe(CN)6]3-
3. [Fe(CN)6]4-
4. Fe2+

Kohlrausch's law states that at

1. Infinite dilution, each ion makes definite contribution to conductance of an electrolyte whatever be the nature of the other ion of the electrolyte
2. Infinite dilution, each ion makes definite contribution to equivalent conductance of an electrolyte, whatever be the nature of the other ion of the electrolyte
3. Finite dilution, each ion makes definite contribution to equivalent conductance of an electrolyte, whatever be the nature of the other ion of the electrolyte
4. Infinite dilution, each ion makes definite contribution to equivalent conductance of an electrolyte depending on the nature of the other ion of the electrolyte.

Standard free energies of formation (in kJ/mol) at 298 K are -237.2, -394.4 and -8.2 for H2O(l), CO2(g) and pentane (g) respectively. The value of E cell for the pentane-oxygen fuel cell is

1. 1.0968 V
2. 0.0968 V
3. 1.968 V
4. 2.0968 V

The equilibrium constant of the reaction: Cu(s) + 2Ag+(aq) Cu2+(aq) + 2Ag(s); E = 0.46 V at 298 K is

1. 2.0 1010
2. 4.0 1010
3. 4.0 1015
4. 2.4 1010

The efficiency of a fuel cell is given by

1. G/ S
2. G/ H
3. S/ G
4. H/ G