(b) What is the difference between a unimolecular and a bimolecular elementary reaction?

Key Concepts

Elementary Reactions

Elementary reactions are the simplest types of chemical reactions that occur in a single step, involving a direct interaction between reactants. They are characterized by their molecularity, which indicates the number of reactant molecules involved in the reaction. Understanding elementary reactions is crucial for analyzing reaction mechanisms and kinetics.

Unimolecular Reactions

Unimolecular reactions involve a single reactant molecule that undergoes a transformation to form products. This type of reaction typically follows first-order kinetics, where the rate of reaction depends solely on the concentration of the single reactant. An example is the isomerization of a molecule, where one molecule rearranges to form another without the involvement of other reactants.

Bimolecular Reactions

Bimolecular reactions involve two reactant molecules that collide and react to form products. These reactions can be either two molecules of the same species or two different species. Bimolecular reactions generally follow second-order kinetics, where the rate of reaction depends on the concentrations of both reactants. An example is the reaction between two different gases to form a product.