Chemistry Worksheets Class 12 on Chapter 3 Electrochemistry with Answers - Set 3

The study of electrochemistry is essential for developing environmentally friendly new technologies. The transmission of sensory signals through cells to the brain and vice versa, as well as communication between cells, are known to have an electrochemical origin. As a result, electrochemistry is a vast and interdisciplinary subject.

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Chemistry Worksheets Class 12 on Chapter 3 Electrochemistry with Answers - Set 3
Chemistry Worksheets Class 12 on Chapter 3 Electrochemistry with Answers - Set 3
Chemistry Worksheets Class 12 on Chapter 3 Electrochemistry with Answers - Set 3

CBSE Class 12 Chemistry Chapter 3 Electrochemistry Worksheet – Set 3

Q-1: Given the EO values for the following reaction sequence,

Mn6+Electrode potential Mn5+Electrode potential Mn4+Electrode potential Mn3+Electrode potential Mn2+

The computed value of EO for Mn6+ →Mn2+(in volts) is ____________.

Q-2: The solubility product of AgBr(s) is 5×10-13 at 298 K. If the standard reduction potential of the half-cell, EO(Ag|AgBr(s)|Br–) is 0.07 V, the standard reduction potential, EO(Ag+|Ag) (in volts) is _________.

Statement for linked answer questions Q-3 and Q-4

The standard half cell reduction potential of Fe3+(aq)|Fe is -0.036 V and that of OH–(aq)| Fe(OH)3(s)| Fe is -0.786 V.

Q-3: For the determination of solubility product (Ksp) of Fe(OH)3, the appropriate cell representation and its emf are, respectively,

  1. Fe|Fe(OH)3(s) |OH–(aq)|Fe3+(aq)|Fe = -0.750 V
  2. Fe|Fe3+(aq)|OH–(aq)|Fe(OH)3(s)| Fe = -0.750 V
  3. Fe|Fe(OH)3(s)|OH–(aq)|Fe3+(aq)|Fe = +0.750 V
  4. Fe||Fe3+(aq)|OH–(aq)|Fe(OH)3(s)|Fe = -0.822 V

Q-4: The value of loge(Ksp) for Fe(OH)3 at 298 K is

  1. -38.2
  2. +87.6
  3. -96.0
  4. -87.6

Q-5: Why is a salt bridge required in a galvanic cell?

Q-6: Why does a solution’s conductivity decrease with dilution?

Q-7: For the concentration cell, M|M+(aq,0.01 mol/dm3)|| M+(aq),0.1 mol/dm3)|M. Calculate the EMF(E) of the cell at a temperature (T) in terms of R(Universal gas constant) and F(Faraday’s constant)

Q-8: The ion conductance of the alkali metal cation at a given concentration follows the following order

  1. Li+>Na+>K+>Rb+
  2. Li+<Na+<K+<Rb+
  3. Li+<Na+<K+>Rb+
  4. Li+=Na+>K+>Rb+

Q-9: The half cell reactions for rusting of iron are:

2H+ +2e– + ½ O2 → H2O(l) Eo= +1.23 V

Fe2+ + 2e– → Fe(s) Eo= -0.44 V

ΔGo( in kJ) for the reaction is

  1. -76
  2. -322
  3. -122
  4. -176

Q-10: Which of the following statements is true regarding the electrical conductivity of HCl in aqueous solution, HCl as a gas and HCl in benzene?

  1. All three conduct electricity because HCl is a strong acid.
  2. HCl in aqueous solution only conducts electricity because it is ionised but not HCl gas and HCl in benzene.
  3. HCl in benzene is not conducting because benzene is a non polar solvent but HCl is gas and HCl in aqueous solution conducts electricity.
  4. HCl in aqueous solution and HCl in benzene are conducting because they are solutions but into HCl gas.

Q-11: Predict the product of electrolysis of an aqueous CuCl2 solution with an inert electrode.

Q-12: For the strong electrolytes NaOH, NaCl and BaCl2, the molar ionic conductivities at infinite dilution are 248.1×10-4,126.5×10-4, and 280×10-4 mho cm2 mol-1 respectively. Calculate the molar conductivity of Ba(OH)2 at infinite dilution.

Q-13: Aluminium is produced by electrolysis of molten Al2O3 in the Hall process. How long would it take a current of 9650 Ampere to produce 120 g of aluminium? (Assume that the current efficiency is 90%.)

Q-14: Which of the following statements is true for an electrochemical cell?

  1. Reduction occurs at H2 electrode
  2. H2 is cathode and Cu is anode
  3. H2 is anode and Cu is cathode
  4. Oxidation occurs at Cu electrode

Q-15: The standard free energies of formation of H2S(g) and CdS(s) at 1000oC are -49.0 kJ/mol and -127.2 kJ/mol respectively. Use these data to predict whether H2(g) will reduce CdS(s) to metallic Cd at this temperature.

Q-16: The density of Cu is 8.94 g/cm3. Find the quantity of electricity needed to plate an area 10 cm ×10 cm to a thickness of 10-2 cm using the CuSO4 solution.

Q-17: a) Define the term degree of dissociation.Write an expression that relates a weak electrolyte’s molar conductivity to its degree of dissociation.

b) For a cell Mg(s)|Mg2+(aq)|| Ag+(aq)|Ag, Calculate the maximum work that can be obtained by operating the cell.

Eo(Mg2+/Mg)= -2.37 V, Eo(Ag+/Ag)=0.8V

Q-18: When a copper wire is immersed in an AgNO3 solution, the solution turns blue because copper

  1. Is oxidised to Cu2+
  2. Is reduced to Cu2
  3. Forms a soluble complex with AgNO3
  4. None of the above

Q-19: When the lead storage battery is discharged, then,

  1. SO2 is evolved
  2. Lead sulphate is consumed
  3. Lead is formed
  4. Sulphuric acid is consumed

Q-20: Ira, a science student, went shopping with her father for a battery for their inverter and camera.They discovered two types of batteries: a lead storage battery and a Ni-Cd storage battery. Later was more expensive, but lighter in weight.Ira insisted on purchasing the more expensive Ni-Cd battery.

(a) Why, in your opinion, did Ira insist on a Ni-Cd battery? Give your reasoning.

(b) Describe the values associated with the preceding decision.

(c) Write the overall cell reaction during discharge.

(d) Can this cell be sealed unlike a lead storage cell?

Download the PDF to access answers to the Chemistry Worksheet for Class 12 Chemistry Chapter 3 Electrochemistry Set -3.
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