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Lecture1710fb - Chemistry 83 11/2/10 Water and Related...

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Chemistry 83 11/2/10 1 Water and Related Technologies Water Fluoridation Soaps and Detergents Bottled Water Potable water is necessary for the survival of living matter • Water makes up 50-90% of the weight of most life-forms • Roles: solvent that carries food to cells and waste from cells • Survival time: about 1 week without water, but two weeks without food Buell/Girarad, Chemistry, 2nd,Jones and Bartlett, MA,2003,282
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Chemistry 83 11/2/10 2 http://www.atslimited.com/img/water_usage.jpg Includes drinking water The average US home uses ~300 gallons of water per day http://ga.water.usgs.gov/edu/graphics/wateruse2000pie.gif U.S. consumes over 400 B gallons of water daily
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Chemistry 83 11/2/10 3 Water cycle is the source of water www.italocorotondo.it/. ../ hydrological_cycle.htm Saline water http://earthobservatory.nasa.gov/Features/WeighingWater/index.php The total volume of water on earth is large (326 M mile 3 ), but water that can readily be made potable is not Water salinity based on dissolved salts in g/ L 0.5 Water salinity based on dissolved salts in g/ L 0.5 - 30 Water salinity based on dissolved salts in g/ L 30 - 50 Water salinity based on dissolved salts in g/ L >50 Freshwater Brackish Saline or saltwater Brine Water salinity classifications Primary source of drinking water in US
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Chemistry 83 11/2/10 4 Run-off water requires the least treatment to make it portable • Runoff water may be contaminated with suspended matter such as finely divided clay, fertilizer, organic pesticides from farming, bacteria from animals, and odors from decaying living matter • Typically runoff water is made potable by treatment with aluminum sulfate, lime, activated charcoal, chlorine and NaF as shown on the next slide Hill/Kolb, Chemistry, 10th, Prentice-Hall,2004, 376 Al(OH) 3 removes suspended matter Charcoal removes organic substances (with charcoal) Aeration removes odors Cl 2 kills bacteria Chemical technologies are used to make surface water potable
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Chemistry 83 11/2/10 5 Many cities also add fluoride to drinking water to decrease tooth decay Enamel consists of closely- packed rods of hydroxyapatite: Ca 5 (OH)(PO 4 ) 3 Dentin is bone-like matter Pulp chamber contains blood vessels and nerves http://www.colgate.com/app/Colgate/US/OC/Information/OralHealthBasics/CommonConcerns/Cavities/IllustrationsHowAToothDecays.cvsp Structure of a Human Tooth http://www.elmhurst.edu/~chm/vchembook/548toothdecay.html
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This note was uploaded on 12/19/2010 for the course CHEM 83 taught by Professor Bonk,j during the Fall '08 term at Duke.

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Lecture1710fb - Chemistry 83 11/2/10 Water and Related...

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