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Chapter 3 The Chemistry of Global Warming

Chapter 3 The Chemistry of Global Warming. Chemistry 1010 Dr. Harris. Suggested Problems. Emphasizing Essentials (pgs. 144 and 145): 2, 7, 9, 16, and 21. Concentrating on Concepts (pg. 146): 33. Exploring Extensions (pg. 147): 46. 3.1 In the Greenhouse.

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Chapter 3 The Chemistry of Global Warming

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  1. Chapter 3The Chemistry of Global Warming Chemistry 1010 Dr. Harris

  2. Suggested Problems • Emphasizing Essentials (pgs. 144 and 145): 2, 7, 9, 16, and 21. • Concentrating on Concepts (pg. 146): 33. • Exploring Extensions (pg. 147): 46.

  3. 3.1 In the Greenhouse • Jean-Baptiste Joseph Fourier (1768-1830) • French mathematician and physicist • Atmosphere and the glass of a “hothouse” or greenhouse. • John Tyndall (1820-1893) • CO2 and H2O vapor absorb heat • Today • CO2 absorbs heat • Atmospheric CO2 concentration has increased over the past 150 years • Earth’s avg. temp has not remained constant

  4. 3.2 The Testimony of Time • Photosynthesis • 6 CO2 + 6 H2O C6H12O6 + 6 O2 • 100 million years ago • Estimated avg. temp 10-15ºC warmer than today • CO2 concentration assumed to be considerably higher chlorophyll glucose

  5. Figure 3.3 Notice the correlation between carbon dioxide and temp. change.

  6. 3.3 The Earth’s Energy Balance Figure 3.4 – Look closely at the width of each arrow.

  7. 3.3 The Earth’s Energy Balance • Global Greenhouse Effect • Return of 84% of the energy radiated from the surface of the Earth • Enhanced Greenhouse Effect • Energy return of greater than 84%

  8. 3.4 Molecules: How They Shape Up • CO2, H2O, and CH4 are greenhouse gases. • N2 and O2 are not greenhouse gases. • Why? • Answer comes from a closer look at the molecular structure and shape.

  9. 3.4 Molecules: How They Shape Up • Review of Lewis structures for N2 and O2 • How about methane’s structure? • Determine # of outer electrons associated with each atom in the molecule. • Remember the octet rule when drawing the molecule. • Most stable molecular shape – bonding and nonbonding electrons are as far from each other as possible. • Let’s look at four different molecular structures (methane, ammonia, water, and carbon dioxide). • Remember structure names and bond angles. • Question 11

  10. 3.5 Vibrating Molecules and the Greenhouse Effect Figure 3.13 – Molecular vibrations in carbon dioxide.

  11. 3.5 Vibrating Molecules and the Greenhouse Effect Figure 3.16 – Molecular response to types of radiation.

  12. 3.5 Vibrating Molecules and the Greenhouse Effect Figure 3.14 Question 12

  13. 3.6 The Carbon Cycle: Contributions from Nature and Humans • 6.0-8.2 Gt – amount of carbon dioxide released by human activities (deforestation/burning fossil fuels) per year. • About ½ of this carbon dioxide is recycled into the oceans and biosphere. • 3.1-3.5 Gt increase of carbon per year. • Question 23 - Interesting

  14. 3.7 Weighing the Unweighable • Atomic mass – average mass of an atom of that element as compared to an atomic mass of exactly 12 amu for carbon-12. • 1 amu = 1.66 x 10-24 g. • Notice that the mass number for carbon is 12.01. • The “.01” comes from the contribution of the carbon-13 and carbon-14. Question 18

  15. 3.7 Weighing the Unweighable • Let’s take a closer look at a laboratory scale. • Can only read to 0.1 mg. • Atomic Mass – can also be defined as the mass (g) of the same number of atoms that are found in exactly 12 g of carbon-12. • # carbon-12 atoms in exactly 12 g = 6.02 x 1023 (Avogadro’s #) One Avogadro’s # of oxygen atoms = 16.00 g.

  16. 3.8 Of Molecules and Moles • Chemists usually don’t work with single atoms or molecules. • We need a chemist’s dozen. • Mole – Avogadro’s number of anything. • You can think of the “mole” as the chemist’s dozen. • C + O2 CO2 • Molar mass – mass of one Avogadro’s number of specified particles. • Molar mass of carbon atoms = 12.0 g.

  17. 3.8 Of Molecules and Moles • Molar mass CO2 = (1 x molar mass C) + (2 x molar mass O) = 44.0 g/mole

  18. 3.9 Manipulating Moles and Mass with Math • Question – what mass of carbon dioxide contains 3.3 Gt of carbon? • What mass units do you want to use? • Let’s work this out to the mass units that you as a class select.

  19. 3.12 Has the Greenhouse Effect Already Started? Figure 3.24

  20. 3.12 Has the Greenhouse Effect Already Started? • Status of text knowledge • Guided by 2001 report from the Intergovernmental Panel on Climate Change (IPCC). • Definitely true: • CO2 contributes to an elevated global temperature. • CO2 concentration in the atmosphere has been increasing over the past century.

  21. 3.12 Has the Greenhouse Effect Already Started? • Very likely: • The increase in CO2 concentration in the atmosphere over the past century is a consequence of human activity. • Virtually certain: • Average global temperature has increased during the past century. • May be true: • CO2 and other gases generated by human activity are responsible for this temperature increase.

  22. 3.12 Has the Greenhouse Effect Already Started? • Uncertain: • The average global temperature will continue to increase as anthropogenic emissions of greenhouse gases increase.

  23. 3.15 Global Warming and Ozone Depletion

  24. End of Chapter 3

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