C

Chain Reaction

X• + RH → R• + HX; R• + X₂ → RX + X•
Quick Reference
Formula / NotationX• + RH → R• + HX; R• + X₂ → RX + X•
Also Known AsChain mechanism, radical chain reaction, nuclear chain reaction, self-propagating reaction

What is Chain Reaction?

A chain reaction is a self-sustaining sequence of reactions in which one of the products or by-products causes subsequent reactions of the same kind. In nuclear chemistry, a chain reaction occurs when neutrons released from fission cause further fissions. In organic chemistry, free radical chain reactions (initiation, propagation, termination) are important in polymerisation and combustion.

Formula & Notation

X• + RH → R• + HX; R• + X₂ → RX + X•

Other Names / Synonyms: Chain mechanism, radical chain reaction, nuclear chain reaction, self-propagating reaction

Properties & Characteristics

A chain reaction is a self-sustaining sequence of reactions in which a reactive intermediate (radical, ion, or neutron) produced in one step triggers subsequent steps, each producing more reactive intermediates. In chemical chain reactions (e.g., radical halogenation), propagation steps regenerate the chain carrier. In nuclear fission, each fission event releases 2-3 neutrons that can trigger further fissions. Chain reactions are characterised by initiation, propagation, and termination steps.

Uses & Applications

Chain reactions are exploited in polymer synthesis (radical chain polymerisation), combustion engineering, explosives design, and nuclear power generation. Understanding chain reactions is critical in designing reactors with controlled criticality and in fire suppression chemistry.

Safety Information

Uncontrolled chain reactions pose severe hazards: nuclear criticality accidents, explosive decomposition of peroxides and certain monomers, and runaway combustion. Inhibitors (chain terminators), critical mass control, and fire suppressants (halons, CO₂) are used as safety measures.

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

Key Facts

Term Chain Reaction
Formula X• + RH → R• + HX; R• + X₂ → RX + X•
Synonyms Chain mechanism, radical chain reaction, nuclear chain reaction, self-propagating reaction

Frequently Asked Questions

A chain reaction is a self-sustaining sequence of reactions in which one of the products or by-products causes subsequent reactions of the same kind. In nuclear chemistry, a chain reaction occurs when neutrons released from fission cause further fissions. In organic chemistry, free radical chain reactions (initiation, propagation, termination) are important in polymerisation and combustion.

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