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Lecture 9

Lecture 9. The Chemistry of Global Warming (cont.) April 22, 2005. In the news. Today is Earth Day – the 35 th annual. http://promo.yahoo.com/earthday05/ Honda Offers Retail Natural Gas Vehicle

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Lecture 9

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  1. Lecture 9 The Chemistry of Global Warming (cont.) April 22, 2005

  2. In the news.... • Today is Earth Day – the 35th annual. • http://promo.yahoo.com/earthday05/ • Honda Offers Retail Natural Gas Vehicle • Honda said the Civic GX can go up to 220 miles without refueling and costs about 3.75 cents per mile to fuel. A conventional, gasoline-powered Civic can go approximately 350 miles without refueling and costs 8.8 cents per mile to fuel. • The Civic GX has some of the lowest emissions of any vehicle on the road, Honda said. On average, a car with a natural gas-powered internal-combustion engine emits 87 percent less nitrogen oxide, 70 percent less carbon monoxide and 25 less carbon dioxide than a car with an engine that uses gasoline, according to Honda. • Refueling? Time-consuming and disadvantageous. • http://www.cnn.com/SPECIALS/2005/changing.earth/ • In the current issue of the journal Science, there is an article titled: Study Shows Antarctic Glaciers Shrinking

  3. The carbon cycle

  4. Another view of the carbon cycle

  5. The carbon cycle: contributions from nature and humans Evaluating the possibility of climate change from increased greenhouse effect. + + + + + + + + How much CO2 contains 3.3 Gt of carbon? In other words, how much CO2 is added to the atmosphere by the burning of fossil fuels?

  6. Atoms are extremely small • In a balloon of hydrogen gas, there are approximately 4×1022 atoms of hydrogen • Stars in the Milky Way Galaxy: 2×1011 • National debt: $6×1012 • Sand grains in Sahara Desert: 2×1024 • Until very recently nobody has ever observed an atom directly - about 0.1 nm diameter

  7. Best view of an atom EM of iron oxide molecules Individual atoms are not visible Scanning tunneling microscope Observing “probe” also moves the atoms Figure shows moved individual Ag atoms

  8. Need a counting unit • Pair: 2 • Dozen: 12 • Gross: 144 • Mole: Number of things in molar mass of something (atomic mass number from the periodic table) – C: 12.01 g – O: 16.00 g – H: 1.008 g What is a mole? How many is a mole?

  9. Using moles? Be careful out there…

  10. Using moles Mole: 6.02×1023 things (Avogadro’s Number) Molar Mass (g) (atomic mass number) Grams # of atoms or molecules Moles = 1 mol 1 mol = 6.02 x 1023 1 Atomic Number (# of protons) H Grams = Mole Atomic Mass (weighted average of isotopes) Hydrogen 1.008

  11. Example How many atoms are in 24 g of carbon? • Calculate number of moles 24 g C x = 1.998 mol C • Calculate the number of atoms 1 mol 12.01 g 6.02 x 1023 mol 1.998 mol C x = 1.2 x 1024 atoms

  12. g mol 1 mol 6.02 x 1023 atoms 14.01 x = 2.3 x 10-23 g Example What is the mass of one atom of nitrogen? Atomic Mass of Nitrogen = 14.01 g/mol

  13. g mol 1 mol 6.02 x 1023 atoms 1.008 x = 1.67 x 10-24 g Example What is the mass of one atom of hydrogen? Atomic Mass of Hydrogen = 1.008 g/mol = 1.67 x 10-27 kg

  14. g mol 1 mol 6.02 x 1023 atoms 1.008 x = 1.67 x 10-24 g Example What is the mass of one atom of hydrogen? Atomic Mass of Hydrogen = 1.008 g/mol = 1.67 x 10-27 kg 1H (1 proton) = ~ 1 g/mol = 1 atomic mass unit (amu) = 1 dalton (biology)

  15. 454 g 1 lb 20 lb x = 9080 g 1 mol 55.85 g 9080 g x = 162 mol 6.02 x 1023 1 mol 162 mol x = 9.75 x 1025 atoms Fe Example How many atoms of iron (Fe) are there in a 20 lb dumbbell?

  16. Stoichiometry Stoichiometry is the study and calculation of quantitative (measurable) relationships of the reactants and products in chemical reactions (chemical equations). Back to our question of how much CO2 is added to the atmosphere by the burning of fossil fuels? In one mole of CO2 molecules, there are one mole of C atoms and 2 moles of O atoms 1 mole C: 12.01 g 2 mole O: 2 x 16.00 g = 32.00 g 1 mole CO2: 12.01 g + 32.00 g = 44.01 g Molecular Weight (CO2)

  17. Using molecular weights How many CO2 molecules are in 5 g of CO2? 1 mol 44.01 g Figure out # of moles 5 g CO2 x = 0.1136 mol CO2 6.02 x 1023 mol 0.1136 mol CO2 x = 6.84 x 1022 CO2 molecules

  18. 1 mol 12.01 g mol CO2 mol C 44.01 g 1 mol 1g C x x x = 3.66 g CO2 Balanced Chemical Equations + C O2 CO2 A mole of C atoms reacts with a mole of O2 molecules to form a mole of CO2 molecules • How much CO2 is formed from 1 g of C? carbon-to-carbon dioxide ratio (mass)

  19. 1000 kg 1 mt 1000 g 1 kg 100 mt C x x = 1 x108 g C Measuring CO2 Output How much CO2 does a power plant produce (emit) if it burns 100 metric tons of coal in a day? 3.66 g CO2 1 g C 1 x 108 g C x = 3.66 x108 g CO2 1 mt 1 x 106 g 3.66 x 108 g CO2x = 3.66 x102 mt CO2

  20. Measuring CO2 Output How much CO2 contains 3.3 Gt of carbon? 3.66 CO2 1 C 3.3 Gt Carbon x = 12.07 Gt CO2 1 x 109 mt 1 Gt 1 x 106 g 1 mt 12.07 Gt CO2x x = 1.2 x1016 g CO2

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