Electrochemistry

For vaporisation of water at 1 atm pressure, the values of ΔH and ΔS are 40.63 kJ mol^- and 108.8 JK^-1 mol^-1, respectively. The temperature when Gibbs energy change (ΔG) for this transformation will be zero, is

• 273.14 K

• 393.4 K 

• 373.4 K 

• 373.4 K 

Al₂O₃ is reduced by electrolysis at low potentials and high currents. If 4.5 x 10⁴ An of current is passed through molten Al₂O₃ for 6h, what mass of aluminium is produced? (Assume 100% current efficiency, at.mass of Al = 27 g mol^-1)

• 9.0 x 10³ g

• 8.1 x 10⁴ g

• 2.4 x 10⁵ g 

• 2.4 x 10⁵ g 

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

• 1.25 x 10^-5

• 1.25 x 10^-6

• 6.25 x 10^-4

• 6.25 x 10^-4

Given, 
(i) Cu²⁺ + 2e^- → Cu,     E^o = 0.337 V

(ii) Cu²⁺ +e^- → Cu⁺, E^o = 0.153

Electrode potential, E^o for the reaction,
Cu +e^- →Cu, will be 

• 0.52 V

• 0.90 V

• 0.30 V

• 0.30 V

The values of ΔH and ΔSfor the reaction, C_(graphite) + CO₂  → 2 CO (g) are 170 kJ and 170 JK^-1 respectively. This reaction will be spontaneous at 

• 710 K

• 910 K

• 1110 K

• 1110 K

Kohlrausch's law states that at

• finite dilution, each ion makes a definite contribution to the equivalent conductance of an electrolyte, whatever be the nature of the other ion of the electrolyte.

• infinite dilution, each ion makes a definite contribution to the equivalent conductance of an electrolyte depending on the nature of the other ion of the electrolyte.

• infinite dilution, each ion makes a definite contribution to the conductance of an electrolyte whatever be the nature of the other ions of the electrolyte.

• infinite dilution, each ion makes a definite contribution to the conductance of an electrolyte whatever be the nature of the other ions 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^o for pentane-oxygen fuel cell is

• 1.968 V

• 2.0968 V

• 1.0968 V

• 1.0968 V

The equilibrium constant of the reaction:

Cu (s) + 2 Ag⁺ (aq) →  Cu²⁺ (aq) + 2 Ag (s);

E^o = 0.46 V at 298 K

• 2.4 x 10¹⁰

• 2.0 x 10¹⁰

• 4.0 x 10¹⁰

• 4.0 x 10¹⁰

The efficiency of a fuel cell is given by:

If  the standard emf of the reaction:

Fe + 2 Fe³⁺ →3Fe²⁺

will be:

• 0.330 V

• 1.653 V

• 1.212 V
• 1.212 V