Cell reaction is spontaneous when
Eored is negative
Eored is positive
ΔGo is negative
ΔGo is positive
The efficiency of a fuel cell is given by
ΔG / ΔS
ΔG / ΔH
ΔS / ΔG
ΔH / ΔG
A hypothetical electrochemical cell is shown below
A | A+ (xM) || B+ (yM) | B
The emf measured is + 0.20 V. The cell reaction is
A + B+ → A+ + B
A+ + B → A + B+
A+ + e- → A; B+ + e- → B
The cell reaction cannot be predicted
On heating one end of a piece of a metal, the other end becomes hot because of
Energised electrons moving to the other end
Resistance of the metal
Mobility of atoms in the metal
Minor perturbation cell in the energy of atoms .
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
EoFe2+/Fe = -0.441 V and EoFe3+/Fe2+ = 0.771 V,
the standard emf of the reaction
Fe + 2 Fe3+ → 3 Fe2+ will be
0.111 V
0.330 V
1.653 V
1.212 V
Cu+ (aq) is unstable in solution and undergoes simultaneous oxidation and reduction according to the reaction
- 0.38 V
+ 0.49 V
+ 0.38 V
- 0.19 V
An electrochemical cell is shown below
Pt, H2 (1 atm) |HCl (0.1 M)| CH3COOH(0.1 M)| H2 (1 atm), Pt. the emf of the cell will not be zero, because
emf depends on molarities of acids used
pH of 0.1 M HCl and 0.1 M CH3CHOOH is not same
The temperature is constant
Acids used in two compartments are different
Equivalent conductance of NaCl, HCl and C2H5COONa at infinite dilution are 126.45, 426.16 and 91 ohm-1 cm2, respectively. The equivalent conductance of C2H5COOH is
201.28 ohm-1 cm2
390.71 ohm-1 cm2
698.28 ohm-1 cm2
540.48 ohm-1 cm2
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
