Electrochemistry · Question 9

The conductivity of centimolar solution of KCl at 25 is 0.0210 ohm-1 cm-1 and the resistance of the cell containing the solution at 25 is 60 ohm. The value of cell constant is -

1. 3.28 cm-1
2. 1.26 cm-1
3. 3.34 cm-1
4. 1.34 cm-1

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R: In the light of the above statements, choose the correct answer from the options given below:

1. Both A and R are true but R is NOT the correct explanation of A.
2. A is true but R is false.
3. A is false but R is true.
4. Both A and R are true and R is the correct explanation of A.

At 298 K, the standard electrode potentials of Cu2+/Cu, Zn2+/Zn, Fe2+/Fe and Ag+/Ag are 0.34 V, -0.76 V, -0.44 V and 0.80 V, respectively. On the basis of standard electrode potential, predict which of the following reaction cannot occur?

1. CuSO4(aq) + Zn(s) ZnSO4(aq) + Cu(s)
2. CuSO4(aq) + Fe(s) FeSO4(aq) + Cu(s)
3. FeSO4(aq) + Zn(s) ZnSO4(aq) + Fe(s)
4. 2CuSO4(aq) + 2Ag(s) 2Cu(s) + Ag2SO4(aq)

Given below are half cell reactions: MnO4- + 8H+ + 5e- Mn2+ + 4H2O, E Mn2+/MnO4- = -1.510 V 12O2 + 2H+ + 2e- H2O E O2/H2O = +1.223 V Will the permanganate ion, MnO4- liberate O2 from water in the presence of an acid?

1. Yes, because E cell = +0.287 V
2. No, because E cell = -0.287 V
3. Yes, because E cell = +2.733 V
4. No, because E cell = -2.733 V

Find the emf of the cell in which the following reaction takes place at 298 K Ni(s) + 2Ag+ (0.001 M) Ni2+ (0.001 M) + 2Ag(s) (Given that E cell = 1.05 V, 2.303 RTF = 0.059 at 298 K)

1. 1.0385 V
2. 1.385 V
3. 0.9615 V
4. 1.05 V

Two half cell reactions are given below. Co3+ + e- Co2+, E0 Co2+/Co3+ = -1.81 V 2Al3+ + 6e- 2Al(s), E0 Al/Al3+ = +1.66 V The standard EMF of a cell with feasible redox reaction will be :

1. -3.47 V
2. +7.09 V
3. +0.15 V
4. +3.47 V

Standard electrode potential for the cell with cell reaction Zn(s) + Cu2+(aq) Zn2+(aq) + Cu(s) is 1.1 V. Calculate the standard Gibbs energy change for the cell reaction. (Given F = 96487 C mol-1)

1. -200.27 J mol-1
2. -200.27 kJ mol-1
3. -212.27 kJ mol-1
4. -212.27 J mol-1

The molar conductance of NaCl, HCl and CH3COONa at infinite dilution are 126.45, 426.16 and 91.0 S cm2 mol-1 respectively. The molar conductance of CH3COOH at infinite dilution is. Choose the right option for your answer.

1. 540.48 S cm2 mol-1
2. 201.28 S cm2 mol-1
3. 390.71 S cm2 mol-1
4. 698.28 S cm2 mol-1

The molar conductivity of 0.007 M acetic acid is 20 S cm2 mol-1. What is the dissociation constant of acetic acid? Choose the correct option. [ H+ = 350 S cm2 mol-1 CH3COO- = 50 S cm2 mol-1]

1. 2.50 10-5 mol L-1
2. 1.75 10-4 mol L-1
3. 2.50 10-4 mol L-1
4. 1.75 10-5 mol L-1

On electrolysis of dil. sulphuric acid using Platinum (Pt) electrode, the product obtained at anode will be :

1. Oxygen gas
2. H2S gas
3. SO2 gas
4. Hydrogen gas