T

Termolecular Reaction

rate = k[A][B][C]
Quick Reference
Formula / Notationrate = k[A][B][C]
Also Known AsThree-body collision, third-order reaction, trimolecular reaction

What is Termolecular Reaction?

A termolecular reaction is an elementary reaction step in which three reactant particles (molecules, atoms, or ions) collide simultaneously to form products. Such reactions are extremely rare because the probability of three particles colliding simultaneously with the correct orientation and energy is very low. Third-order reactions in practice usually proceed by two-step mechanisms involving a bimolecular step.

Formula & Notation

rate = k[A][B][C]

Other Names / Synonyms: Three-body collision, third-order reaction, trimolecular reaction

Properties & Characteristics

Three-body collision required. Extremely low probability — simultaneous three-body collision is rare. Rate law: rate = k[A][B][C]. Third-order kinetics. Examples: 2NO + O₂ → 2NO₂ (proposed but actually two-step). 2NO + Cl₂ → 2NOCl (appears termolecular). Atom recombination in gas phase (M serves as third body).

Uses & Applications

Understanding complex reaction mechanisms. Atmospheric chemistry (recombination reactions with M = N₂ or O₂). Combustion chemistry. Kinetics of radical recombination reactions.

Safety Information

Conceptual kinetics term — no direct safety concerns.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Termolecular Reaction
Formula rate = k[A][B][C]
Synonyms Three-body collision, third-order reaction, trimolecular reaction

Frequently Asked Questions

A termolecular reaction is an elementary reaction step in which three reactant particles (molecules, atoms, or ions) collide simultaneously to form products. Such reactions are extremely rare because the probability of three particles colliding simultaneously with the correct orientation and energy is very low. Third-order reactions in practice usually proceed by two-step mechanisms involving a bimolecular step.

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