Unimolecular reaction

Definition

A unimolecular reaction is a chemical reaction in which a single reactant molecule undergoes a transformation to yield products. These reactions are typically characterized by first-order kinetics.

5 Must Know Facts For Your Next Test

1. A unimolecular reaction involves only one reactant molecule in the rate-determining step.
2. The rate law for a unimolecular reaction is first-order, expressed as $rate = k[A]$.
3. Unimolecular reactions can occur through processes such as isomerization or dissociation.
4. The rate constant ($k$) for a unimolecular reaction depends on temperature and can be influenced by the presence of catalysts.
5. Lindemann-Hinshelwood mechanism often explains the kinetics of gas-phase unimolecular reactions.

Review Questions

• What is the order of kinetics for a unimolecular reaction?
• Describe an example of a process that can occur via a unimolecular reaction.
• How does the Lindemann-Hinshelwood mechanism explain the behavior of unimolecular reactions?

Related terms

Bimolecular Reaction: A chemical reaction involving two reactant molecules in the rate-determining step, typically exhibiting second-order kinetics.

Rate-Determining Step: The slowest step in a multi-step reaction mechanism that determines the overall reaction rate.

First-Order Kinetics: Reaction kinetics where the rate depends linearly on the concentration of one reactant, expressed as $rate = k[A]$.