Ozone Decomposition by UV
2O3 → 3O2
Overview
UV-C radiation (< 240 nm) and UV-B (240–320 nm) break ozone back into molecular oxygen and atomic oxygen. This absorption of UV is precisely what protects life on Earth. The steady-state balance between ozone formation and decomposition maintains the ozone layer thickness.
Participants
| Role | Substance | Coefficient | State |
|---|---|---|---|
| Reactant | Ozone O₃ | 2 | (g) |
Everyday Example
Sunscreen with high SPF is needed because not all UV is filtered by ozone — the remaining UV-A and some UV-B still reach the surface.
Industrial Importance
Understanding ozone photochemistry is critical for monitoring the ozone hole and predicting UV exposure levels worldwide.
Properties
- Type
- Photochemical
- Reversible
- No
- Energy
- Exothermic
- ΔH
- -285.4 kJ/mol
Related Reactions
Chlorophyll Fluorescence
Cis-Trans Isomerization of Retinal
Dye-Sensitized Solar Cell (Grätzel Cell)
Firefly Bioluminescence (Luciferin Oxidation)
Luminol Chemiluminescence
Ozone Formation by UV Light
Photocatalytic NOx Removal
Photocatalytic Water Splitting (TiO₂)
Photochemical Cycloaddition ([2+2])
Photochemical Smog Formation (NO₂ Photolysis)
Frequently Asked Questions
What is the equation for Ozone Decomposition by UV?
The balanced equation is: 2O₃ → 3O₂.
What type of reaction is Ozone Decomposition by UV?
Ozone Decomposition by UV is a photochemical reaction.
Is Ozone Decomposition by UV exothermic or endothermic?
Ozone Decomposition by UV is exothermic (releases energy). The enthalpy change (ΔH) is -285.4 kJ/mol.