On the basis of the information available from the reaction
4/3 Al + O2 → 2/3 Al2O3, ΔG = - 827 KJ mol-1 of O2 , the minimum emf required to carry out the electrolysis of Al2O3 is (F = 96500 C mol-1)
2.14 V
4.28 V
6.42 V
8.56 V
On the basis of the following Eo values, the strongest oxidising agent is
[Fe(CN)6]4-
Fe2+
Fe3+
[Fe(CN)6]3-
Al2O3 is reduced by electrolysis at low potentials and high currents. If 4.0 × 104 A 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)
9.0 × 103 g
8.1 × 104 g
2.4 × 105 g
1.3 × 104 g
Which one of the following pairs of substances on reaction will not evolve H2 gas?
Iron and H2SO4 (aqueous)
Iron and Steam
Copper and HCl (aqueous)
Sodium and Ethyl alcohol
Cu+ (aq) is unstable in solution and undergoes simultaneous oxidation and reduction according to the reaction
2 Cu+ (aq) Cu2+ (aq) + Cu (s)
Choose the correct Eo for above reaction if
- 0.38 V
+ 0.49 V
+ 0.38 V
- 0.19 V
In electrolysis of NaCl when Pt electrode is taken then H2 is liberated at cathode while with Hg cathode it forms sodium amalgam because
Hg is more inert than Pt
More voltage is required to reduce H+ at Hg than at Pt
Na is dissolved in Hg while it does not dissolve in Pt
Concentration of H+ ions is larger when Pt electrode is taken
The most convenient method to protect the bottom of the ship made of iron is
Coating it with red lead oxide
White tin plating
Connecting it with Mg block
Connecting it with Pb block
4.5 g of aluminium (at. mass 27 u) is deposited at cathode from Al3+ solution by a certain quantity of electric charge. The volume of hydrogen produced at STP from H+ ions in solution by the same quantity of electric charge will be
44.8 L
22.4 L
11.2 L
5.6 L
The specific conductance of a 0.1 N KCl solution at 23o C is 0.012 ohm-1 cm-1. The resistance of cell containing the solution at the same temperature was found to be 55 ohm. The cell constant will be
0.142 cm-1
0.66 cm-1
0.918 cm-1
1.12 cm-1
Cell reaction is spontaneous when
Eored is negative
Eored is positive
ΔGo is negative
ΔGo is positive
