Chemical kinetics is a study of the rates of reactions and mechanisms which occur at various conditions and concentrations for different substances. Chemical kinetics is defined as studying rates of chemical reactions at different temperatures, pressures, and concentrations. There are two different types or classes of chemical reaction viz. 

1) Spontaneous Reactions: A spontaneous reaction is a reaction that occurs without any input of energy from the surroundings to help it along. Spontaneous reactions involve decreasing the total molecular potential energy (entropy). No heat is produced during such a reaction because heat consists of disordered molecular motion.

2) Non-spontaneous reactions: A non-spontaneous reaction is a reaction that takes place due to a change in the surroundings, and hence it requires the input of energy. The chemical reactions that occur by the automatic mechanism are called Reactions (A), and non-spontaneous reactions are called Non-Reactions (B).

NCERT solutions of chemical kinetics explain various reactions' physical, chemical, and mathematical principles. In this article, we have given some chemical kinetics class 12 NCERT solutions, which will help the students clear their basic chemistry concepts and solve the questions with ease.

 

A reaction occurs when atoms or groups form new molecules by combining with other atoms or groups to form new molecules.

The change in the number of atoms or groups is called the Nucleation, and this happens very fast compared to the rate of formation of products. In this reaction, a large number of species are formed at once. Molecularity is involved in the process of all types of chemical reactions. A chemical reaction that occurs without any change in atomic and molecular structure is non-molecular. In contrast, a chemical reaction that requires a change in atomic and molecular structure is termed a molecular reaction.

 

Catalyst is a substance that enhances the rate of a chemical reaction, making it happen more quickly.

There are two types of catalyst, viz.

1) Heterogeneous catalysts: These catalysts are compounds that can dissolve into both the reactants and products. They act as an aid to chemical reactions.

2) Homogeneous catalysts: These catalysts are substances that can dissolve only in one phase

 

The reaction rate increases as the temperature increases because energy is released in heat and becomes available to do work. The rate at which a substance releases energy depends upon its heat capacity, latent heat of fusion, and specific heat capacity.

The rate of any reaction is proportional to the number of collisions occurring in a given period. Collision Theory of Chemical Reactions states that the collision frequency is directly proportional to the total volume of the reacting substances. In other words, it is stated that given the same volume, which contains the same number of molecules and atoms, a reaction will occur with a maximum frequency in a smaller amount of space because more collisions will occur within lower dimensions. In simple terms, this means that the same amount of energy is being released by the collisions as initially used to break up any molecule. The release mechanism or collision theory is how energy is released during this reaction.

The formation rate is the rate at which a reaction results in forming a product. It is defined as the number of moles formed over time equals the number of moles consumed, measured in moles per second. The rate of disappearance is defined as the product and heat change over time. The heat change (ΔT) minus ΔH (energy) is often given as ΔH – T ≈ 0, where T = Time, depending on experimental conditions. Therefore, the sum of the rate of disappearance is equal to the rate of formation.

In a chemical reaction, energy changes a reactant into a product. Different factors such as temperature, catalysts, and reaction conditions play significant roles in determining the rate of a reaction. But finally, it is the number of molecules of the substances that are undergoing a change that decides the reaction rate. The significant factors that affect the rates of chemical reactions are given below:

 

1) Temperature: One of the most critical factors affecting chemical reactions is essential in accelerating or inhibiting them. As the temperature increases, more molecules collide with each other, and hence this results in increasing molecular speed, in turn leading to an increase in temperature.

2) Pressure: Pressure affects the reaction in two ways. Firstly, it slows down the reaction, and secondly, it affects the reaction rate by driving the reactants and products to one side of a vessel.

 

3) Mass action: In this case, it becomes essential to know whether a process is spontaneous or nonspontaneous. A slow supply of energy doesn't significantly affect the reaction rate in mass action, even though it is not very effective.

4) Concentration: Higher concentration of reactants also affects the rate of chemical reactions. In this case, the higher the concentration of reactants, the higher their chances of colliding with each other.

 

5) Catalysts: Catalysts are generally used to speed up chemical reactions. They also increase the reaction rate by providing a surface to collide.

 

6) Chain Reaction: Another reaction is caused by energy being transferred from one molecule to another. Therefore, it can repeatedly occur in a chain, resulting in an almost constant reaction rate. These reactions always occur in two stages: the initiation stage and the propagation stage. The substances that take part in these reactions are always much more than one because it involves a chain reaction where many particles interact with each other simultaneously.

 

Chemical kinetics is an essential subject in the area of chemistry. It helps understand the rates of various chemical reactions. The rates of chemical reactions are affected by significant factors like temperature, concentration, pressure, and catalysts. Changing the levels of these factors can cause changes in the reaction rate and help us learn how to control it effectively. The better understanding of the various concepts presented in chemical kinetics, the more you will solve problems about these reactions. Class 12 chemical kinetics NCERT solutions cover all the essential topics for students to learn. However, chemical kinetics is a field where complex concepts are studied, so it is challenging to understand these concepts thoroughly in a single go. In this article, we have tried to provide some NCERT solutions of chemical kinetics, which will help the students clear their chemistry concepts. Download Msvgo App today to clarify your doubts and get quick chemical kinetics NCERT maths solutions.

 

FAQ:

Q1: What is the need for chemical kinetics?

A1: Chemical dynamics is the study of how different reagents react. In this case, it is essential to understand what needs to be known about the reactions, how they behave, and why reactions occur or don't occur in appropriate conditions.

Q2: What is the chemical reaction rate?

A2: The speed at which reaction occurs (m/s) can be calculated by dividing the number of reactants consumed in a given time with the original concentration (moles per m).