The Extraordinary Properties of Water：水的特殊性质ppt课件.ppt

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1、Whatmakeswatersospecial?WaterAwatermolecule(H2O),ismadeupofthreeatoms---oneoxygenandtwohydrogen.HHOSo…whatmakeswatersospecial?WaterisPolar!!!!Theoxygenend“acts”negativeThehydrogenend“acts”positiveCausesthewatertobePOLAR,likeamagnet.HydrogenBondsExistBetween

2、WaterMoleculesFormedbetweenahighlyElectronegativeatom(likeoxygeninanotherwater)ofapolarmoleculeandahydrogenWeakbond,butstrongingreatnumbers(askaboutCrocodileDundee)InteractionBetweenWaterMoleculesNegativeOxygenendofonewatermoleculeisattractedtothePositiveHy

3、drogenendofanotherwatermoleculetoformaHYDROGENBONDWhatarethePropertiesofWater?PropertiesofWaterCohesionPropertiesofWaterCohesionAdhesionPropertiesofWaterCohesionAdhesionHighSpecificHeatPropertiesofWaterCohesionAdhesionHighSpecificHeatHighHeatofVaporizationP

4、ropertiesofWaterCohesionAdhesionHighSpecificHeatHighHeatofVaporizationLessDenseasaSolidCohesionAttractionbetweenparticlesofthesamesubstance(whywaterisattractedtoitself)Resultsinsurfacetension(ameasureofthestrengthofwater’ssurface)Cohesion…Helpsinsectswalkac

5、rosswater,buthowisithelpfultopeople?AdhesionAttractionbetweentwodifferentsubstances.Waterwillmakehydrogenbondswithothersurfacessuchasglass,soil,planttissues,andcotton.Capillaryaction-watermoleculeswill“tow”eachotheralongwheninathinglasstube.AdhesionCausesCa

6、pillaryActionWhichgiveswatertheabilityto“climb”structuresHighSpecificHeatAmountofheatneededtoraiseorlower1gofasubstance1°C.Waterresiststemperaturechange,bothforheatingandcooling.Wouldyouratherwalkonsandorinwateronabeachonahotsummerday?Whichwouldbewarmerthat

7、night?Why?HighHeatofVaporizationWatervaporformsakindofglobal‘‘blanket”whichhelpstokeeptheEarthwarm.Heatradiatedfromthesunwarmedsurfaceoftheearthisabsorbedandheldbythevapor.WaterisLessDenseasaSolidWhichisiceandwhichiswater?Solutions&SuspensionsWaterisusually

8、partofamixture.Therearetwotypesofmixtures:Solutions:substancedissolvesinliquidSuspensions:substancesuspendsinliquidComeupwithexamplesSolutionsWateristhesolvent,saltisthesolutesaltwateristhesolutionSus