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Oxidation/Reduction & Batteries. Oxidation. Combining with Oxygen – combustion Gives off energy Oxidation in the body – H 2 O and CO 2 Oxidation in an engine – above plus CO and NOx’s Degree of oxidation – CO not totally oxidized Rusting of Iron. Oxidation.
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Oxidation • Combining with Oxygen – combustion • Gives off energy • Oxidation in the body – H2O and CO2 • Oxidation in an engine – above plus CO and NOx’s • Degree of oxidation – CO not totally oxidized • Rusting of Iron
Oxidation • Gaining oxygen or loosing electrons 2Na + Br2→ 2Na+ + 2Br- → 2NaBr • Which looses electrons? • F, Cl, Br, I are common oxidizing agents • Oxidizing agents cause other substances to be oxidized
Reduction • Oxidation/Reduction like Acid/Base • Always in pairs • Instead of exchanging protons, exchanging: • Electrons • Oxygen • Losing oxygen or gaining electrons • Memory table • Metal ores are oxidized metals, must be reduced
Reduction • Reducing agents cause other substances to be reduced. • What are anti-oxidants?
Reduction • Anti-oxidants are electron donors • Reduce potential oxidizing agents • Free radicals – unpaired electron wants another • Takes electrons – oxidizes • Vitamins A, C, and E
Strengths of Redox Agents • So zinc is more active than copper • So iron is more active than copper • Is iron or zinc more active? – How do you tell? • The more active a metal is, the more it wants to be oxidized or ionized.
Batteries • Based on activity of metals, etc. • Something oxidized that wants to be reduced • Something reduced that wants to be oxidized
Batteries • Based on activity of metals, etc. • Something oxidized that wants to be reduced • Something reduced that wants to be oxidized • Store electricity as chemical energy • Primary batteries – cannot be recharged • Dry cells, alkaline, lithium • Secondary batteries – rechargeable • NiCad, NiMH, Lead acid, rechargeable alkaline, Lithium ion • Which is better for the environment?
Lead Acid Batteries(car batteries) • During recharging the following also occurs: • Is there a danger here?
H28 – C12 • 1 - 5, 8 - 10, 13 - 16, 24, 26, 27, 29, 47 - 51, 53, 54