Photodissociation of Chlorine Gas
Cl2 → 2Cl·
Overview
UV or visible light (< 500 nm) cleaves the Cl–Cl bond homolytically to produce two chlorine free radicals. This is the initiation step in many radical chain reactions, including the chlorination of hydrocarbons. Each chlorine radical can propagate thousands of reaction cycles before termination.
Everyday Example
The chlorination of methane to produce chloromethane begins with this UV-initiated splitting of chlorine gas.
Industrial Importance
Free radical chlorination is used to manufacture chlorinated solvents, PVC (polyvinyl chloride), and various chlorinated organic compounds.
Properties
- Type
- Photochemical
- Reversible
- No
- Energy
- Endothermic
- ΔH
- 242.6 kJ/mol
Related Reactions
Chlorophyll Fluorescence
Cis-Trans Isomerization of Retinal
Dye-Sensitized Solar Cell (Grätzel Cell)
Firefly Bioluminescence (Luciferin Oxidation)
Luminol Chemiluminescence
Ozone Decomposition by UV
Ozone Formation by UV Light
Photocatalytic NOx Removal
Photocatalytic Water Splitting (TiO₂)
Photochemical Cycloaddition ([2+2])
Frequently Asked Questions
What is the equation for Photodissociation of Chlorine Gas?
The balanced equation is: Cl₂ → 2Cl·.
What type of reaction is Photodissociation of Chlorine Gas?
Photodissociation of Chlorine Gas is a photochemical reaction.
Is Photodissociation of Chlorine Gas exothermic or endothermic?
Photodissociation of Chlorine Gas is endothermic (absorbs energy). The enthalpy change (ΔH) is 242.6 kJ/mol.