Answer: Cl• + O3 → ClO• + O2; then ClO• + O• → Cl• + O2; the Cl• is regenerated catalytically destroying thousands of O3 molecules.
- A Cl• + O3 → ClO• + O2; then ClO• + O• → Cl• + O2; the Cl• is regenerated catalytically destroying thousands of O3 molecules
- B Cl• directly and largely irreversibly reacts with atmospheric N2 gas to permanently form nitrogen trichloride during normal conditions
- C Cl• is mostly consumed by forming stable HCl gas with little further ozone destruction occurring afterward, as generally observed
- D Cl• reacts harmlessly with O2 gas to form a fairly stable, largely unreactive ClO2 species in typical laboratory settings
Correct answer: A. Cl• + O3 → ClO• + O2; then ClO• + O• → Cl• + O2; the Cl• is regenerated catalytically destroying thousands of O3 molecules
Explanation: This is the catalytic ozone depletion cycle. Cl• is not consumed; it is regenerated after each cycle, meaning a single Cl atom can destroy up to 100,000 ozone molecules before being deactivated.
SN2 proceeds in a single step with backside attack and inversion of configuration, while SN1 forms a planar carbocation intermediate first, leading to racemisation.
Concept context
Study carbon-halogen compounds: how they are made, how they react via SN1/SN2 and elimination, their stereochemistry, and their environmental impact.