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Chapter 4

Chapter 4. Air. Our atmosphere Troposphere – ground to 10 km (6 miles) up Stratosphere – up to 50 km above earth Ozone layer – part of the lower stratosphere, contains high levels of ozone. Our atmosphere is about 78% nitrogen, 21% oxygen, and 1% all other gases

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Chapter 4

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  1. Chapter 4 Air

  2. Our atmosphere • Troposphere – ground to 10 km (6 miles) up • Stratosphere – up to 50 km above earth • Ozone layer – part of the lower stratosphere, contains high levels of ozone

  3. Our atmosphere is about 78% nitrogen, 21% oxygen, and 1% all other gases • Everywhere you are on Earth these percentages are relatively constant.

  4. Concentrations? • PPM • PPB • PPT

  5. Useful gases • Our atmosphere can be separated into each individual gas. • Some of these gases have very important uses others are just useful in some ways

  6. Nitrogen • Boiling point is -196 C (-320 F) • Uses: • Liquid nitrogen • Cryogenics • cryosurgery • food preparation and shipping • Inert atmosphere

  7. Nitrogen to Nitrate

  8. Oxygen • LOX – liquid oxygen • Boiling point -186 C (-302 F) • Uses: • Steelmaking • Rocket propulsion • Extremely reactive

  9. Noble Gases • Neon, Argon, Krypton, Xenon, Helium

  10. Other uses: • Argon – used as inert atmosphere in metal work and chemical reactions • Helium - ?

  11. Pollution • What are some types of pollution? • What are some sources?

  12. Natural pollution • Ash • Mercury vapor • Hydrogen chloride • Hydrogen sulfide • Carbon dioxide • Chlorinated organic compounds

  13. Man made – anthropogenic pollution • Same as the natural pollutants, and more • Hydrocarbons • How deadly is air pollution?

  14. Air Pollution • What are pollutants? • Particulates – solid matter suspended in air • Aerosols – liquid particles in the air, usually much larger than the particulates and can have trillions of atoms in a single droplet

  15. Particulates

  16. Results – lung and eye irritants • Global cooling by reflecting sunlight • Concentration of particles is usually 0.00001 g/m3 • High concentrations may be .002 g/m3

  17. Aerosols • Size ranges from 1nm to 10,000 nm • 2,000 nm and larger can cause visual distortion • Small enough to remain suspended in air for long periods of time

  18. Health hazards – • Can contain high concentrations of pollutants • Carcinogenic compounds • Mutagenic compounds

  19. Smog • London • Industrial smog – related to the burning of coal • Las Angeles • Photochemical smog – combustion engine pollutants

  20. Conditions for smog • Thermal inversion

  21. Industrial smog • Main ingredient – sulfur dioxide • Produced/released by the burning of coal • Can form H2SO4 (sulfuric acid) • 1952 London Fog disaster • 4,000-12,000 deaths

  22. Prevention • Filter pollutants

  23. Photochemical smog

  24. Not sulfur dioxide related • Nitrogen oxides • Ozone • Oxygenated and ozonated hydrocarbons • Unreacted hydrocarbons

  25. Pollutants • Primary - Produced directly from things like car engines and industrial processes • Secondary – produced when primary pollutants react and form new pollutants

  26. Car engine combustion creates NO2 (primary) • NO2 and sunlight can create Ozone (secondary)

  27. Homework for chapter 4 will be available this afternoon. • Exam grades will hopefully be viewable on OWL this afternoon as well.

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