NCERT Solutions for Class 12 Chemistry Chapter 3 – Electrochemistry

NCERT Solutions for Class 12 Chemistry Chapter 3 – Electrochemistry covers all the aspects of chemical reactions generating electricity and electricity carrying out chemical reactions dealt in this chapter. In this chapter of NCERT Solutions, you will learn about electrochemical, galvanic and electrolytic cells. You will also learn about various thermodynamic terms used in electrochemistry and methods of measuring conductivity and other related parameters of a solution. You will also learn Kohlrausch’s law and qualitative and quantitative aspects of electrochemistry.

There are 18 questions asked at the end of the chapter from the different concepts taught in NCERT CBSE Class 12 Chemistry Chapter 3. The direct and numerical questions in the exercise are based on electrochemical reactivity series, galvanic cells, Nernst equation, both laws of Faraday and conductivity of a solution.

The solutions of Class 12 Chemistry Chapter 3 – Electrochemistry follow the directives given by CBSE and NCERT. They help you understand the fundamental concepts thoroughly so that you can solve all the questions from this chapter asked in the CBSE Board exam questions paper.

NCERT Class 12 Chemistry Chapter 3

NCERT Solutions for Class 12 Chemistry Chapter 3 – Electrochemistry covers all the concepts given in the unit. They enable you to delve deep into the concepts taught in this chapter. The outline of the concepts covered in this chapter has been given below.

  • Electrochemical cells

This part of the chapter tells you that an electrochemical cell consists of two electrodes and an electrolyte which is the conducting solution. Electrochemical cells are of two types, namely, galvanic cells and electrolytic cells. In galvanic cells, chemical energy derived from a spontaneous reaction is converted into electrical work. An electrolytic cell utilises electricity to carry out a chemical reaction which is otherwise not spontaneous.

  • Galvanic cells

NCERT Class 12 Chemistry Chapter 3 tells you that the chemical reactions can be divided into oxidation half and reduction half-reactions taking place at anode and cathode electrodes, respectively. The potential difference developed between the electrodes is known as electrode potential. The standard electrode potential for any electrode dipped in a proper solution is defined with respect to standard electrode potential of hydrogen electrode considered as zero. The standard potential of a cell is obtained by calculating the difference between electrode potentials of its electrodes.

  • Nernst Equation

This part of the chapter tells you that the Nernst equation deals with concentration dependence of the potentials of electrodes and cells. It also helps to determine the equilibrium constant of reactions in equilibrium. 

cell = E°cell + (RT/nF) ln {[Ox]/[Red]}

  • Electrochemical cell and Gibbs energy of a reaction 

This portion teaches you that the standard potential of the cells is related to standard Gibbs energy (ΔrGθ = -nFEθcell) and equilibrium constant of the reaction occurring in the cell (ΔrGθ = – RT ln K).

  • The Conductance of Electrolytic Solutions

This part of the chapter tells you that in case of an electrolytic solution, its conductivity or specific conductance, κ, is dependent upon the concentration of the electrolyte, nature of solvent and temperature. It is expressed in S m-1 and is the inverse of resistivity of a solution.

  • Measurement of the Conductivity of Ionic Solutions

This part of the chapter tells that accurate measurement of resistance of an electrolytic cell is done through a conductivity cell passing AC current. Here The term Molar conductivity (Λm) is used, which is related to the conductivity of the solution of concentration c by the equation, Λm = κ/c and takes the units S cm2 mol-1.

  • Variation of Conductivity and Molar Conductivity with Concentration 

This part of the chapter teaches you that conductivity is decreased, but molar conductivity is increased when the concentration of a solution is decreased. When concentration becomes almost zero, the molar conductivity of a solution is called limiting molar conductivity (Λ°m). 

Further, it tells you that Λm increases slowly with dilution in case of strong electrolytes as they are highly dissociated from the starting. Kohlrausch law of independent migration of ions implicates that molar conductivity of an electrolyte at infinite dilution is the sum of the contribution of the molar conductivity of the ions in which it dissociates. This law finds its application in many places.

You further learn here that molar conductivity increases steeply in case of weak electrolytes with increasing dilution.

  • Electrolytic cells and Electrolysis

This part of the chapter tells you about the process of Electrolysis and how many metals are produced commercially using this. Further, you come to know about the quantitative aspect of Electrolysis which is explained by Faraday’s two laws of Electrolysis. First law relates the amount of chemical reaction happening and current passed in a direct manner and second law states that an equal quantity of electricity would deposit different substances according to their equivalent weights.

It further tells you that charge on one mole of electrons is known as 1 Faraday and is equal to 96487 C.

  • Batteries 

This part of the chapter enables you to know that batteries are the storehouse of electrical energy as they convert chemical energy to the former. In primary batteries, a reaction occurs only once and the battery becomes dead over a period of time. Leclanche cell and mercury cell are common examples in this case. Secondary batteries are recharged on passing external current, lead storage battery and Ni-Cd cell are common examples here.

  • Fuel Cells

This part of the chapter tells you that fuel cells are galvanic cells designed to convert the energy of combustion of fuels like hydrogen, methane, methanol etc. to electrical energy directly. 

  • Corrosion 

Here you learn that corrosion is nothing but an electrochemical phenomenon where metal is oxidised by loss of electrons to oxygen formation of its oxides.

CBSE NCERT Class 12 Chemistry Chapter 3 Exercise

Our NCERT Solutions for Chapter 3 – Electrochemistry consists of 18 questions covering the important concepts learnt. The components of the exercise have been listed below. 

  • Questions 1, 2, 17 and 18 are based on reactivity series and use your application skills.
  • Questions 3 and 4 are based on the galvanic cell.
  • Question 5 is numerical and is based on the Nernst equation.
  • Question 6 asks you to determine the reaction parameters.
  • Question 7 is a direct question on conductivity and molar conductivity of the solution.
  • Questions 8 to 11 are numerical questions based on conductivity.
  • Questions 12 to 16 are numerical problems based on Faraday’s law of Electrolysis.

This chapter of CBSE NCERT Class 12 Chapter 3 also contains 12 intext questions after the main concepts taught in this chapter. All of these questions have been answered systematically in our solutions. 

Benefits of NCERT Solutions for Class 12th Chemistry Chapter 3 – Electrochemistry

Some of the key benefits of learning and revising from NCERT Solutions for Class 12 Chemistry Chapter 3 – Electrochemistry are listed below.

  • Solutions of the questions are given in step by step manner so that you can develop a solid conceptual base.
  • They are well-organised and follow a logical flow to help you learn and revise faster during exams.
  • They are to the point yet descriptive so that you can learn faster and learn effectively.
  • They imbibe the concepts of electrochemistry well within you, helping you to practically use the same if required during higher studies. 
  • Our NCERT Solutions make learning fun, interesting and engaging. They make learning a more stimulating, enjoyable and happy process.
  • They cover a wide range of question types important from an exam point of view.