CBSE PREVIOUS YEAR QUESTIONS OF CHAPTER3 (ELECTROCHEMISTRY) - CLASS12 CHEMISTRY

 CBSE Questions Chapter- 03 

( ELECTROCHEMISTRY)

2007

1)Define conductivity and molar conductivity for the solution of an electrolyte?

2)On the basis of standard electrode potential values stated for acid solution, predict whether Ti⁴⁺ species may be used to oxidize Fe^II and Fe^III

Reaction                                                                                  E^O/V

Ti^IV + e^--à Ti³⁺                                                                                      +0.01

Fe³⁺ + e^-à Fe²⁺                                                                                     +0.77

3) Calculate the standard cell potentials of galvanic cell in which the following reaction

take place:

(i) 2Cr(s) + 3Cd²⁺(aq) → 2Cr³⁺(aq) + 3Cd

Calculate the ΔrG0 value for the reaction.

Given E⁰(Cr³⁺/Cr) = -0.74 V ; E⁰ ( Cd²⁺/Cd) = -0.40 V , F= 96500 C mol^-1)

2008

1)Express the relation between the conductivity and molar conductivity of a solution

2)Depict the galvanic cell in which the reaction

Zn(s) + 2Ag⁺ (aq)à Zn²⁺(aq) + 2Ag(s)

Takes place. Further indicate what are the carriers of the current inside and outside the cell. State the reactions at each electrode

3)The resistance of a conductivity cell containing 0.001M KCl solution at 298K is 1500Ω. What is the cell constant if the conductivity of 0.001M KCl solution at 298K is 0.146×10^-3 S cm^-1

4) Conductivity of 0.00241 M acetic acid is 7.896 × 10^–5 S cm^–1. Calculate its molar

conductivity and if Λ_m⁰ for acetic acid is 390.5 S cm² mol^–1, what is its dissociation constant?

5) Three electrolytic cells A,B,C containing solutions of ZnSO₄, AgNO₃ and CuSO₄,

respectively are connected in series. A steady current of 1.5 amperes was passed

through them until 1.45 g of silver deposited at the cathode of cell B. How long did the current flow? What mass of copper and zinc were deposited?

2009

1)What type of cell is a lead storage battery? Write the anode and cathode reactions and the overall cell reaction occurring in the use of a lead storage battery?

2)A copper- silver cell is set up. The copper ion concentration in it is 0.10M. The concentration of silver ion in it is not known The cell potential measured is 0.422V. Determine the concentration of silver ion in the cell.

(E^O_Ag+/Ag=+0.80V, E^O_Cu2+/Cu=0.34V)

3) Two half cell reactions of an electrochemical cell are given below:

MnO^4- + 8 H⁺ + 5e^- à Mn²⁺ = 4H₂O , E⁰ = + 1.51 V

Sn²⁺ à Sn ⁴⁺ + 2e^- , E⁰ = + 0.15 V

Construct the redox equation and predict if this reaction favors the formation of reactants or products shown in the equations

4) A voltaic cell is set up at 25⁰C with the following half cells:

Al| Al³⁺ (0.0010 M) and Ni | Ni²⁺ (0.50 M)

Write the equation for the cell reaction that occurs when the cell generates an electric current and determine the cell potential.

(Given E0 (Ni²⁺/Ni) = -0.25 V , E0 (Al³⁺/Al) = -1.66 V)

2010

1)Fluoride does not exhibit any positive oxidation state. Why?

2)Express the relation among the cell constant, the resistance of the solution in the cell and the conductivity of the solution. How is the conductivity of a solution related to its molar conductivity?

3)Given that the standard electrode potentials (E^O) of metals are

K⁺+/K=-2.93v, Ag⁺/Ag=0.80V,Cu²⁺/Cu=0.34V,Mg²⁺/Mg=2.97V,Cr³⁺/Cr=-0.74V, Fe²⁺/Fe=-0.44V.

Arrange these metals in an increasing order of their reducing power.

4) ) Two half cell reactions of an electrochemical cell are given below:

MnO^4- + 8 H⁺ + 5e^- à Mn²⁺ = 4H₂O , E⁰ = + 1.51 V

Sn²⁺ à Sn ⁴⁺ + 2e^- , E⁰ = + 0.15 V

Construct the redox equation and predict if this reaction favors the formation of reactants or products shown in the equations.

2011

1)a)What type of battery is a lead storage battery? Write the anode and cathode reactions and the overall cell reaction occurring in the operation of a lead storage battery

b)Calculate the potential for half cell containing 0.1M k₂Cr₂O₇(aq), 0.2M Cr³⁺(aq) and 1.0 × 10 ^-4 M H⁺(aq). The half cell reaction is

Cr₂o₇(aq)+14 H⁺(aq)+ 6e^-à2Cr³⁺(aq) + 7H₂o.    ( Given E⁰ for half cell = 1.33 V)

2012

1) Express the relation among cell constant, resistance of the solution in the cell and conductivity of the solution. How is molar conductivity of a solution related to its conductivity?

2) The molar conductivity of a 1.5 M solution of an electrolyte is found to be 138.9 S cm² mol^-1. Calculate the conductivity of this solution.

3) A voltaic cell is set up at 25⁰C with the following half cells:

Al| Al³⁺ (0.0010 M) and Ni | Ni²⁺ (0.50 M)

Write the equation for the cell reaction that occurs when the cell generates an electric current and determine the cell potential.

(Given E0 (Ni²⁺/Ni) = -0.25 V , E0 (Al³⁺/Al) = -1.66 V)

4) The electrical resistance of a column of 0.05 M NaOH solution of diameter  1 cm and length 50 cm is 5.55 × 10³ ohm . Calculate its resistivity , conductivity and molar conductivity.

2013

2014

1. State Kohlrausch law of independent migration of ions. Why does the conductivity of a solution decrease with dilution?

2. (a) Calculate Δ_rG^o for the reaction

Mg (s) + Cu²⁺ (aq) à Mg²⁺ (aq) + Cu (s)

Given: E^o_cell = +2.71 V, 1F = 96500 C/mol

(b) Name the type of cell which was use in Apollo space program for providing electrical power.

3. 3) Define the fllowing terms-  

i) Fuel Cell  ii) Limiting molar conductivity (Ʌ⁰_m

2015

1.  Calculate the time to deposit  1.17 g of ni at cathode when a current of 5 A was passed through the solution of Ni(NO₃)₂.  ( Molar mass of Ni=58.5 g mol^-1, 1F = 96500 C mol^-1)

2. Calculate E⁰_cell for the following reaction at 25⁰C :-

A  + B²⁺  ( 0.001 M ) à A²⁺  (0.0001 M)  + B

Given : E_cell = 2.6805 , 1 F= 96500 C mol-1)

2016

(a) Calculate ΔG⁰ and log Kc for the following reaction at 298 K:

2Al(s) + 3 Cu²⁺ (aq) à 2Al³⁺ (aq) + 3 Cu (s)                   Given : E⁰ cell = 2.02 V

(b) Using the E⁰ values of A and B , predivt which is better for coating the surface of iron [ E⁰ ( Fe²⁺/Fe) = -0.14 V] to prevent corrosion and why ?

Given E⁰ ( A²⁺/A) = -2.37 V, E⁰ (B²⁺/B) = -0.14 V

(c) The conductivity of 0.001 mol L^-1 solution of CH₃COOH is 3.905 × 10^-5 S cm^-1. Calculate its molar conductivity and degree of dissociation(α).

Given λ⁰(H⁺) = 349.6 S cm²mol^-1 and       λ⁰(CH₃COO^-) = 40.9 S cm² mol^-1

(d) What type of battery is dry cell ? Write the overall reaction occuring in dry cell

2017

1. Write the name of the cell used in hearing aids. Write the electrode reactions

2. Write the name of the cell used in inverters. Write the electrode reactions

3. 1.       The cell where the following reaction occurs

2Fe³⁺  ( aq)  +  2 I^-  (aq)  à  2 Fe²⁺  (aq) +  I₂ (s) has E⁰_(cell) = 0.236 V at 298 K . Calculate the standard Gibbs energy of the cell reaction . ( Given : 1 F = 96500 C mol -1 )

How many electrons flow through a metallic wire if a current of 0.5 A is passed for 2 hours ? ( Given : 1 F = 96500 C /mol )

Thank you for visiting the web page. I'll keep updating the page time to time. 
If you find this helpful please share with your Classmates.

MANISH KR SONI

PGT CHEMISTRY

KV BONDAMUNDA