Chem 115 Lecture_28

Chem 115 Lecture_28 - This week in CHM 115 Check out of...

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This week in CHM 115 Check out of lab. Remember: Safety goggles Appropriate dress Final Exam: Tuesday, December 11, 10:30 PM Hall of Music ~60 % cumulative, ~40 % new material
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What do we do when the oil runs out? Energy sources in the U.S.A. We have lots of coal and natural gas but burning them adds to the CO 2 in the atmosphere
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Solar energy striking the U.S.A Energy used in the U.S.A. Perhaps the answer lies elsewhere.
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Solar energy Black body Solar cell Plants ______________ Wind (windmills) Electricity __________ Fossil fuels __________ Conversion of solar energy All are renewable or produce no CO 2
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What is renewable energy? Energy derived from the _____ ________________ ___________________ produced in the last 10 years (with the exception of older garbage in land fills). Biomass all _____________________________ materials including animal manure, not just starch, sugar, and oil crops already used for food and energy. only current renewable source of ___________ ________________________________________
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Relative energy of fuels Biofuels are liquids and are very useful because they can serve as fuel for transportation vehicles. ΔH kJ/g of fuel 2H 2 (g) + O 2 (g) 2H 2 O(l) ΔH = - 142.9 kJ/g CH 4 (g) + O 2 (g) CO 2 (g) + 2H 2 O(l)ΔH = - 55.58 kJ/g Ethanol: C 2 H 5 OH(g) + 3O 2 (g) 2CO 2 (g) + 3H 2 O(l) ΔH = _______ kJ/g Biodiesel: CH 3 (CH 2 ) 16 CO 2 CH 3 (l) + 28.5 O 2 (g) 19CO 2 (g) + 19H 2 O(l)
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Produced from the reaction of water with hydrocarbons and coal and by the electrolysis of water, adding to atmospheric CO 2 load. C(s) + 2H 2 O(g) CO 2 (g) + 2H 2 (g) CH 4 (g) + H 2 O(g) CO(g) + 3H 2 (g) CO(g) + H 2 O(g) CO 2 (g) + 3H 2 (g) 2H 2 O(l) O 2 (g) + 2H 2 (g) (where does electricity come from?) These are no commercial routes to green hydrogen, yet. electrolysis Hydrogen
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Some ______________ _____________ produce hydrogen from water using light energy. oxygen is also produced & enzyme systems can be oxygen sensitive _____________________ may solve the problem Used in fuel cells to produce electricity. Challenges carry useful quantities on mobile platforms delivery to filling stations expensive catalysts required for fuel cell See: http://en.wikipedia.org/wiki/Hydrogen_production Hydrogen
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H 2 2H + + 2e - O 2 + 4H + + 4e - 2H 2 O Net reaction: 2 H 2 + O 2 2H 2 O ~0.65 V Pt Hydrogen fuel cell
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CH 3 OH + H 2 O => CO 2 + 6H+ + 6e- Cathode Reaction: 3/2 O 2 + 6 H+ + 6e- => 3 H 2 O Overall Cell Reaction:
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Chem 115 Lecture_28 - This week in CHM 115 Check out of...

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