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CHEM 304 - 2/15/ 12

CHEM 304 - 2/15/ 12. I.C Strat . Chemistry: Catalytic Ozone Depletion - Catalyst “Families” ( HO x , NO x , ClO x ) - Reaction Paths/Cycles (#1, #2, #3) - Sources of HO x , NO x , ClO x Web updated today (HW #3, #4, and O 3 key) QUIZ M on see – email/web for scope.

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CHEM 304 - 2/15/ 12

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  1. CHEM 304 - 2/15/12 I.C Strat. Chemistry: Catalytic Ozone Depletion - Catalyst “Families” (HOx, NOx, ClOx) - Reaction Paths/Cycles (#1, #2, #3) - Sources of HOx, NOx, ClOx Web updated today (HW #3, #4, and O3 key) QUIZ M on see – email/web for scope.

  2. 3 Main (1 + additional) Catalytic Families: “HOx”: H, OH, HO2 “NOx”: NO, NO2, (NO3- technically not included) “ClOx”: Cl, ClO, (ClO2) “BrOx”: Br, BrO, (BrO2- ? May not exist ? )

  3. NO + O3 —> NO2 + O2 NO2 + O3 —> NO + O2 Write a 2-reaction path 1 cycle w/ X=NO.

  4. NO + O3 —> NO2 + O2 NO2 + hn —> NO + O Write a 2-reaction path 2 “null” cycle w/ X=NO.

  5. HO + O3 —> HO2 + O2 HO2+ O3 —> HO + O2 Write a 2-reaction path 3 cycle w/ X=OH.

  6. Some lingo regarding “Trace species” (e.g. pollutants, reactive substances, etc.) Source: reaction or process that release trace compound. Sink: Reaction or process that “permanently” removes trace compound. Reservoir: An entity (process, substance, physical feature) that temporarily holds a trace substance

  7. Catalyst Sources: Substance must be resilient to these key (tropospheric) loss processes. • Wet Deposition or “rain out”: Is it H2O Soluble? • Reaction w/ OH: Does it have an H? • Photochemistry: Does it absorb >300nm?

  8. Absorption spectra of CFC’s

  9. Vertical Distribution of CFC’s…

  10. Lifetimes of CFC’s and related compounds this graphic does not work

  11. A real world question: How might you modify the structure of a CFC to yet reduce its contribution to stratospheric ClOx, yet retain, as much as possible, its physical properties? (Hint: How would you keep it out of the stratosphere …)

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