Molecularity of a Reaction: The molecularity of a reaction depends on the number of reactant molecules or particles that are involved in the elementary reaction, which is the smallest step in the reaction mechanism. The knowledge of molecularity is important for understanding reaction kinetics and designing reaction mechanisms.

Molecularity of a Reaction

The molecularity of a reaction is a term used to describe the number of molecules or particles that are involved in the elementary reaction that leads to the overall reaction.

For a reaction to occur, reactant molecules or particles must come into contact with each other and interact in a specific way, which leads to the formation of products. The simplest type of reaction is a unimolecular reaction, which involves only one molecule, such as the decomposition of hydrogen peroxide:

2H₂O₂ → 2H₂O + O₂

In this reaction, one molecule of hydrogen peroxide decomposes into water and oxygen. Therefore, the molecularity of this reaction is 1.

Bimolecular reactions involve the collision of two molecules or particles, such as the reaction between hydrogen and chlorine:

H2 + Cl₂ → 2HCl

In this reaction, one molecule of hydrogen reacts with one molecule of chlorine to form two molecules of hydrogen chloride. Therefore, the molecularity of this reaction is 2.

Termolecular reactions involve the collision of three molecules or particles, but they are relatively rare because the probability of three molecules colliding at the same time and in the right orientation is very low.

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By Team Learning Mantras