Chapter 3 - In the Greenhouse In In the Greenhouse In...

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Unformatted text preview: In the Greenhouse In In the Greenhouse In Light (energy) of many wavelengths from the sun strikes the Earth ~55% never reaches earth – absorbed (25%) (like UV with O3) or reflected by the atmosphere (30%) other ~45% is absorbed by the surface of the earth – continents and ocean In the Greenhouse In earth is warmer (59 ºF) than the surrounding space (-454 ºF), the absorbed energy is re-radiated, mostly as IR the atmosphere traps (absorbs) ~81% of this heat fairly constant temperature maintained In the Greenhouse In Is the greenhouse effect bad? A natural atmospheric effect natural Necessary for the Earth to remain warm enough to Necessary support life as we know it support Consider the following: Pressure % CO2 96% .04% Something to do with CO2 Venus Earth 90 atm 1 atm Average tem p 840º F 59º F w/o G. E. 212º or 100º F C 0º or -18º F C In the Greenhouse In What do CO2 and H2O do? 1860s – Tyndall showed that CO2 and H2O absorb absorb heat (N2 and O2) do not heat calculated effect this should have on the earth’s calculated temp based on abundance and distance from the sun – consistent with actual average temperature sun Gathering Evidence: The Testimony of Time The Historical Data – the relationship between CO2 and Temperature CO Data comes from ocean floor and ice cores Data covering past 180,000 years depth of sample allows assignment of a date (age) CO2 levels in the atmosphere measured from air bubbles trapped in ice bubbles Global temperature measured by ratio of “heavy” Global water water Gathering Evidence: The Testimony of Time The Gathering Evidence: The Testimony of Time The Gathering Evidence: The Testimony of Time The predictions are of a continued rise: •United Nations: 1.4 - 5.8ºC rise by 2100 •Others, assuming doubling rate of CO2 emissions: 1.0 - 3.5ºC Gathering Evidence: The Testimony of Time The Global Warming: Global an enhanced greenhouse effect; an enhanced a rise in global temperatures resulting when rise the atmosphere absorbs more than the usual amount of the earth’s radiating heat amount due to elevated levels of greenhouse gases, due such as CO2 such Molecules and Shape Molecules N2 and O2 .. .. .. .. linear O=O :N≡N: symmetrical Molecules and Shape Molecules Valence Shell Electron Pair Repulsion theory Valence (VSPER) (VSPER) Electrons are negatively charged Electrons Groups of electrons (lone pairs or bonds) repel Groups each other each Lone pairs and bonds will arrange themselves Lone around a central atom so that they are as far apart as possible (largest angle) as Molecules and Shape Molecules Linear Molecules – two things on central Linear atom atom CO2 – two bonds, no lone pairs on central atom 180° angles Molecules and Shape Molecules Trigonal Planar Molecules – three things on Trigonal central atom central SO3 – three bonds, no lone pairs 120 ° angles 120 angles O S O O Molecules and Shape Molecules Trigonal Planar Molecules – three things on Trigonal central atom central O3 – two bonds, one lone pair ~120° angles Molecules and Shape Molecules Tetrahedral Molecules – four things on Tetrahedral central atom central CH4 – four bonds, no lone pairs 109.5 ° angles 109.5 angles H C H H H Molecules and Shape Molecules Trigonal pyramidal– four things on central Trigonal atom atom NH3 – three bonds, one lone pair ~109.5 ° angles ~109.5 angles Molecules and Shape Molecules Tetrahedral Molecules – four things on central Tetrahedral atom atom H2O – two bonds, two lone pairs ~109.5 ° angles ~109.5 angles Vibrating Molecules and the G.E. Vibrating Energy/Wavelength a. b. Symmetric stretch Asymmetric stretch None in IR range 4.7x10-20J/4.26μm c. Horizontal bend 1.3x10-20J/15.00μm d. Vertical bend Vibrating Molecules and the G.E. Vibrating Other Greenhouse Gases Other H2O Most abundant GG – up to 5% at 100% humidity Not as “good” a GG as CO2 O CO2 H H High natural abundance - .04% Better GG than water Chief man-made GG Lifetime of 5-200 years O C O Other Greenhouse Gases Other CH4 20x better than CO2 .5% as abundant (and rising) Short lifetime – 12 years Sources Digestive system of some animals H C H H H 500L/cow/day 73 million metric tons/year total Warming of frozen land and ocean Other Greenhouse Gases Other O3 2000x better than CO2 Much less abundant – few ppm O O O CFCs 20,000x better than CO2 Much less abundant Other Greenhouse Gases Other NOT Greenhouse Gases: N2 and O2 – can only stretch symmetrically and :N≡N: .. .. O=O .. .. The Carbon Cycle The Carbon Cycle Carbon A steady state cycle – as much CO2 is returned to the atmosphere as is removed. the The Carbon Cycle The Natural Source (CO2 into atmosphere) Plant respiration Animal respiration Soil respiration Uptake in plants Uptake in oceans Uptake in soil Stored as fossil fuel Natural Sinks (CO2 out of atmosphere) The Carbon Cycle The The Carbon Cycle The Main Human Sources of CO2 fossil fuel burning (coal, oil (gasoline) and natural fossil gas for energy) gas CO2 Emissions from Fossil Fuels Emissions deforestation 2 football fields of rainforest per second lost globally the loss of CO2 storage capacity for land replanted with crops is ~80% (even if cut wood is used for lumber not burning or decomposing, which releases CO2) burning The Carbon Cycle The Tens of billions of tons of C per year pass Tens between land and atmosphere between Nearly 100 billion tons of C diffuse back and Nearly forth between ocean and atmosphere forth Does the few billion tons released by humans Does really make a difference? really The Carbon Cycle The Some proposed additional Carbon Sinks: Planting new trees Filter CO2 from power plant emissions and pipe it down to deep ocean where water pressure would squeeze it into liquid form and it would pool on the bottom. the Inject into deep rock (if in oil or natural gas field Inject can help extract last of resource) can Estimated possible storage in the US 40-50 billion metric tons of CO2 into depleted oil reserves reserves 80-100 billion metric tons of CO2 into gas reservoirs 15-20 billion metric tons of CO2 into old coal beds into The Carbon Cycle The Some data Average surface air temperature has risen .7-.8ºC Average since 1900 since CO2 levels (now 370ppm) expected to reach 5601000ppm by 2100 (temp. up another 1.4-5.8ºC) 11 warmest years since the beginning of 11 instrumental records occurred since 1990 The Carbon Cycle The Some data ocean temps have risen since the 50s mountain glaciers are retreating snowfall is less droughts are more severe in Asia and Africa sea levels have risen 10-20 cm since 1900 – sea thermal expansion and melting glaciers thermal polar ice in the arctic decreased 3%/decade temp. over arctic summer sea increased temp. 1.22ºC/decade starting in 1980 1.22ºC/decade arctic as a whole has warmed 8 times faster in the arctic past 20 years than in the past 100 past The Carbon Cycle The Some data more rainfall, earlier snowmelt, more drought 15% loss in arctic tundra since 1970s 3%/decade decrease in perennial sea ice 9%/decade summer sea ice decrease tree line moving north permafrost warming – buildings/roads collapsing increased glacier flow in Greenland – could affect increased sea-level sea-level .88m rise would flood homes of 20-60 million people in .88m India India How much carbon dioxide is produced by burning one gallon of gasoline?? burning Mass, Molecules and Moles Mass, 1 H 1.008 6 C 12.01 28 Ni 58.69 58.69 g of Ni = 6.02 x 1023 nickel atoms 12.01 g of C = 6.02 x 1023 carbon atoms 1 hydrogen atom, on average, weighs 1.008 hydrogen amus (atomic mass units) amus 1.008 g of H = 6.02 x 1023 hydrogen atoms Mass, Molecules and Moles Mass, Avogadro’s Number = 6.02 x 1023 1mole = 6.02 x 1023 of anything 12 eggs = 1 dozen 23 6.02 x 1023 eggs = 1 mole eggs Mass, Molecules and Moles Mass, 1 mole of rice grains would cover the land area of mole the earth to a depth of 75m the it is more rice than has been grown since the it beginning of time beginning the rice would fill a cube 120 miles on each edge A mole of hockey pucks would be equal in mass to mole the moon the A mole of baseballs would fit in a bag the size of the mole earth earth If each person has 6 trillion cells (6 x 1013) and there and are ~5 billion people on earth (1960) (5 x 109) are together we have ~3 x 1023 cells – half a mole together Mass, Molecules and Moles Mass, Molar Mass = mass of 1 mole of something Molar mass of element = mass number in Molar periodic table periodic 1 mole of H weighs 1.008g 1 mole of C weighs 12.01g 1 mole of Ni weighs 58.69g Molar mass of molecule = sum of molar Molar masses of every element in the formula masses 1 mole of CO2 contains 1 mole of C x 12.01g = 12.01 2 moles of O x 16.00g = 32.00 Total = 44.01 g/mole CO2 Molar mass of CO2 is 44.01 g/mole Molar Mass, Molecules and Moles Mass, Converting grams to moles and moles to Converting grams grams The molar mass is a conversion factor Grams to moles: 1mole CO 2 300 g CO 2 × = 6.82 moles CO 2 44.01 g Moles to grams: 50 moles CO 2 × 44.01g = 2200.5 g CO 2 1 mole CO 2 Mass, Molecules and Moles Mass, Moles and chemical equations Combustion of octane 2 C8H18 + 25 O2 → 18 H2O + 16 CO2 18 This tells us: Or Or Or BUT NOT 2 molecules C8H18 → 16 molecules CO2 18 4 molecules C8H18 → 32 molecules CO2 8 molecules C8H18 → 64 molecules CO2 2 moles C8H18 → 16 moles CO2 2 grams C8H18 → 16 grams CO2 Climate Modeling Climate International Panel on Climate Change International (IPCC) (IPCC) Carbon dioxide contributes to an elevated Carbon global temperature. Concentration of carbon dioxide in the Concentration atmosphere has been increasing over the past century. The increase in carbon dioxide is a The consequence of human activity. Average global temperature has increased over Average the last 100 years. Climate Modeling Climate International Panel on Climate International Change (IPCC) Change Anthropogenic carbon dioxide and other gases Anthropogenic are responsible for the temperature rise. The average global temperature will continue to The increase if anthropogenic carbon dioxide emissions continue to increase. emissions Climate Modeling Climate Some Predictions Global mean sea level will rise 9-88cm between Global 1990 and 2100 due to thermal expansion of water and melting ice, endangering New York, New Orleans, Miami, Venice, Bankok, Taipei, etc. New More weather extremes (flood, storm drought) Habitats and ranges of plants and animal Habitats species may change species Increase in disease due to increase in Increase geographic range of carrier insects geographic Climate Modeling Climate Response Reduce fossil fuel use: Increase energy efficiency (power plants, vehicles) Reduce energy use – personal and commercial Make use of alternative energy sources Discontinue deforestation Difficulties fossil fuels are currently the most available and fossil affordable energy source affordable the U.S. economy is based on fossil fuels – the highest per capita reliance highest developing nations become CO2 producers 85% of the world’s energy comes from fossil 85% fuels fuels Kyoto Protocol Kyoto 1997 – Kyoto Conference, 161 countries established goals to reduce atmospheric established greenhouse gas levels greenhouse hope to reduce emissions in developed hope countries by 5% by 2008 – 2012 countries calls for reduction of: 7% of 1990 level for U.S. 8% of 1990 level for E.U. 6% of 1990 level for Canada and Japan Kyoto Protocol Kyoto Review: Global Warming vs. Ozone Depletion Review: Review: Global Warming vs. Ozone Depletion Review: ...
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