Chlorine Nitrate
Definition and meaning of Chlorine Nitrate in chemistry.
Chlorine nitrate (ClONO2) is a reactive stratospheric compound formed when chlorine monoxide radicals combine with nitrogen dioxide, acting as a temporary reservoir that locks both species out of ozone-destroying catalytic cycles.
In more detail
By combining ClO and NO2 into one stable molecule, chlorine nitrate suppresses ozone loss, since neither species can drive catalytic ozone destruction while bound together. During Antarctic winter, heterogeneous reactions on the surfaces of polar stratospheric clouds convert chlorine nitrate back into reactive chlorine (as Cl2 and HOCl), which photolyzes in the returning spring sunlight to release chlorine atoms that rapidly destroy ozone. This storage-and-release cycle is a key mechanism behind the seasonal Antarctic ozone hole.
Key facts
| Formula | ClONO2 |
|---|---|
| Molar Mass | ≈97.46 g/mol |
| Role | Stratospheric chlorine/nitrogen reservoir species |
| Field | Inorganic Chemistry |
Formation reaction: ClO + NO2 + M → ClONO2 + M, a three-body recombination in which M (e.g., N2) is a collision partner that carries away excess energy.
Frequently asked questions
Why is chlorine nitrate called a reservoir species?
Because it temporarily traps reactive chlorine (ClO) and reactive nitrogen (NO2) in one inert molecule, preventing them from participating in catalytic ozone-destroying reactions until the compound breaks down.
How does chlorine nitrate contribute to the ozone hole?
On the surfaces of polar stratospheric clouds in winter, it reacts heterogeneously with HCl or H2O to release active chlorine species like Cl2 and HOCl, which photolyze in spring sunlight to produce ozone-destroying chlorine atoms.