Electrochemistry

Standard reduction potentials of the half reactions are given below : F2(g) + 2e- 2F-(aq); E = +2.85 V Cl2(g) + 2e- 2Cl-(aq); E = +1.36 V Br2(l) + 2e- 2Br-(aq); E = +1.06 V I2(s) + 2e- 2I-(aq); E = +0.53 V The strongest oxidising and reducing agents respectively are

1. F2 and I-
2. Br2 and Cl-
3. Cl2 and Br-
4. Cl2 and I2

Molar conductivities ( m) at infinite dilution of NaCl, HCl and CH3COONa are 126.4, 425.9 and 91.0 S cm2 mol-1 respectively. ( m) for CH3COOH will be

1. 425.5 S cm2 mol-1
2. 180.5 S cm2 mol-1
3. 290.8 S cm2 mol-1
4. 390.5 S cm2 mol-1

Limiting molar conductivity of NH4OH [i.e. 0m(NH4OH)] is equal to

1. 0m(NH4OH) + 0m(NaCl) - 0m(NaOH)
2. 0m(NaOH) + 0m(NaCl) - 0m(NH4Cl)
3. 0m(NH4OH) + 0m(NH4Cl) - 0m(HCl)
4. 0m(NH4Cl) + 0m(NaOH) - 0m(NaCl)

A solution contains Fe2+, Fe3+ and I- ions. This solution was treated with iodine at 35 C. E for Fe3+/Fe2+ is +0.77 V and E for I2/2I- = 0.536 V. The favourable redox reaction is

1. I2 will be reduced to I-
2. there will be no redox reaction
3. I- will be oxidised to I2
4. Fe2+ will be oxidised to Fe3+

Standard electrode potential of three metals X, Y and Z are -1.2 V, +0.5 V and -3.0 V respectively. The reducing power of these metals will be

1. Y > Z > X
2. Y > X > Z
3. Z > X > Y
4. X > Y > Z

The electrode potentials for Cu2+(aq) + e- Cu+(aq) and Cu+(aq) + e- Cu(s) are +0.15 V and +0.50 V respectively. The value of E Cu2+/Cu will be

1. 0.500 V
2. 0.325 V
3. 0.650 V
4. 0.150 V

Standard electrode potential for Sn4+/Sn2+ couple is +0.15 V and that for the Cr3+/Cr couple is -0.74 V. These two couples in their standard state are connected to make a cell. The cell potential will be

1. +1.19 V
2. +0.89 V
3. +0.18 V
4. +1.83 V

Which of the following expressions correctly represents the equivalent conductance at infinite dilution of Al2(SO4)3. Given that Al3+ and SO42- are the equivalent conductances at infinite dilution of the respective ions?

1. 2 Al3+ + 3 SO42-
2. Al3+ + SO42-
3. ( Al3+ + SO42-) 6
4. 13 Al3+ + 12 SO42-

Consider the following relations for emf of an electrochemical cell (i) EMF of cell = (Oxidation potential of anode) − (Reduction potential of cathode) (ii) EMF of cell = (Oxidation potential of anode) + (Reduction potential of cathode) (iii) EMF of cell = (Reduction potential of anode) + (Reduction potential of cathode) (iv) EMF of cell = (Oxidation potential of anode) − (Oxidation potential of cathode) Which of the above relations are correct?

1. (iii) and (i)
2. (i) and (ii)
3. (iii) and (iv)
4. (ii) and (iv)

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