Physical chemistry Class-12 Chapter-3 Electrochemistry Most VVI Subjective Questions

Q.1. Write the differences between electrochemical cell and electrolytic cell ?

Ans:- Electrochemical Cell: (i) It converts chemical energy into electrical energy.

(ii) Salt bridge is used.

(iii) Anode works as -ve charge and Cathode works as +ve charge.

Electrolytic Cell: (i) It converts electrical energy into chemical energy.

(ii) Salt bridge is not used.

(iii) Anode works as +charge and Cathode works as -ve charge.

Q.2. What is standered electrode potential (E⁰) ? 

Ans:- The potential difference developed between the metal electrode and the  electrolyte of unit molarity (1M) at 1 atm pressure and 25⁰C (298k) is called standard electrode potential.

Q.3. Write Faraday’s laws of electrolysis ?

Ans:- First law:- Mass of substance deposited at an electrode is directly proportional to amount of charge passed through solution.


Second law:- If same quantity of charge is passed through different electrolytic solution then substance will be equal.

Q.4. What is cell constant ? 

Ans:- The ratio of the distance between the electrodes divided by the area of cross section of the electrode is called as cell constant.

Q.5. What is Salt bridge ? What are its uses ?

Ans:- In electrochemistry it is a laboratory device used to connect the oxidation and reduction half-cells of a galvanic cell (voltaic cell) a type of electrochemical cell. Salt bridge usually come into two types: glass tube and filter paper.

It is used in voltaic cell. It completes the circuit. It eliminates liquid junction potential.

Q.6. What is a primary cell ? Give an example.

Ans:- The cell which produces electrical energy by irreversible chemical reaction within the cell is called a primary cell. The primary cells cannot be charged for repeated use. Example : Dry cell, Daniell cell.

Q.7. Define Electrochemical equivalent (Z)  ?

Ans:- If I = 1Ampere and t = 1sec 


Thus, the electrochemical equivalence may be defined the amount of the substance deposited by passing 1 Ampere of current for 1 sec or by passing 1 Coulomb of charge through the electrolyte.

Q.8. What is lead storage cell ?

Ans:- In these cells, the electrical energy stored in the form of chemical energy . therefore this cells are called lead storage cells.

Q.9. Why does the conductivity of a solution decrease with dilution ?

Ans:- The conductivity of a solution is related with the number of ions present per unit volume of the solution. When the solution is diluted, the number of ions decreases. Hence, conductivity on a specific conductance of the solution also decreases.

Q.10. Why does conductivity of solution of electrolyte increases by heating ?

Ans:- On increasing temperature the average kinetic energy increases in solution and hence electrical conductivity increases.


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