Electrochemistry · Question 37

How many gram of cobalt metal will be deposited when a solution of cobalt (II) chloride is electrolyzed with a current of 10 amperes for 109 minutes ( 1 Faraday = 96,500 C; Atomic mass of Co = 59 u)

1. 4.0
2. 20.0
3. 40.0
4. 0.66

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)