Chemical Kinetics Class 12 Notes Chapter 4

According to the CBSE Syllabus 2023-24, this chapter has been renumbered as Chapter 3.

The study of chemical reactions concerning the rate of reaction, the formation of intermediates, the rearrangement of atoms, and the effect of different variables is called chemical kinetics. Factors affecting the rate of reaction are the catalyst concentration of reactants and temperature. The rate of reaction cannot be predicted but has to be determined experimentally. Rate law gives the mathematical representation of the rate of reaction.

Rate Constant

The power of concentration of the reactant in the rate law equation is the order of a reaction with respect to a reactant. Therefore to calculate the order of a reaction, add the powers of concentrations of all the different reactants in the equation. The order of reaction, as well as the rate constant, can be determined by the rate law.

Arrhenius Equation

In the year 1899, two concepts were combined to get the Arrhenius equation. The combined concepts are the Boltzmann distribution law and activation energy.

k = A.e–Ea/RT

Ea is the activation energy

A is Arrhenius factor

The above relation was got by Swedish chemist Svante Arrhenius and hence named after him.

Few Important Questions

  1. Calculate the rates of production of H2 and N2 if the decomposition of NH3 on a platinum surface is a zero-order reaction. k = 2.5 × 10–4 mol–1 L s–1
  2. The given equation log k = 14.34 – 1.25 × 104K/T is the rate constant for the first-order decomposition of H2O2. Find Ea and temp at which its half period will be equal to 256 minutes.
  3. Show that, for a first-order reaction, the time needed to complete 99 per cent is double the time needed to complete a 90 per cent reaction.
  4. Calculate the half-life of a first-order reaction for the rate constant 200 s–1
Also Access 
NCERT Solutions for Class 12 Chemistry Chapter 4
NCERT Exemplar for Class 12 Chemistry Chapter 4

Understand the in-depth concepts of chemical kinetics by downloading the Chemical Kinetics Class 12 Notes PDF. For the latest updates, register with BYJU’S now!

For more questions on Chemical Kinetics and Surface Chemistry, watch the below video

Other Important Links:

Arrhenius Equation Rate Constant and Temperature Order of Reaction

Frequently Asked Questions on CBSE Class 12 Chemistry Notes Chapter 4 Chemical Kinetics


What are the main functions of surface chemistry?

Enzymatic reactions at the biological interfaces are found in the cell walls and membranes. In the electronics industry, they are used in the surface and interface of microchips found in computers.


What is the ‘Arrhenius equation’?

The Arrhenius equation describes the relationship between the rate of reaction and temperature for many physical and chemical reactions.


What is the rate of a reaction?

The rate of a reaction is the speed at which a chemical reaction proceeds.


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