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Lecture1710fb - Chemistry 83 Water and Related Technologies...

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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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