人教版高二下学期13单元课堂教学READING课件.ppt

Period2,Reading(2),Waterisaliquidatroomtemperature,andithasarelativelyhighfreezingpoint.Thereasonwhywatercandissolvemostsubstancesonearthisthatwaterhashighheatcapacity.Likealltheothersubstances,watergetssmaller(contract缩小)whenitfreezes.Purewaterhasahigherfreezingpointandlighterthansaltwater.Thesalinityoftheearthsoceansisabout3.5%.Whenwaterfreezes,itsdensityincreases.Otherrecoursessuchasoil,gas,goldetcisaspreciousasadropofrain.,Quiz:TrueorFalse,Lifefirstappearedintheblueseas.,Naturalselection,Adiverseworld,99%ofthelivingspaceonearthisintheoceans.,Whatdoesthisfactresultin?Canyougivesomespecificnumbersorexamples?Whatdoesthisfactimply?Doyouagree?,Marinelifeisincrediblyrichandvaried.,5millionspeciesintheoceans,Waterisanexcellentmediumforlife.Whydoyouagreewithit?,Waterisaliquidatroomtemperatureandhasarelativelyhighfreezingpoint;Alllivingcreaturesneedfoodtosurvive,butonmanyoccasionsthenutrientsbecomeavailabletolivingthingsonlywhentheyaredissolvedbywater.,Watersuniquechemicalstructure,OxygenAtom,HydrogenAtom,Apolarmolecule,Wecangetalotofnutrientsbydrinkingsoup.Plantscanpullwateruptheirrootsviaacapillary(毛细管)process.,Canyougivesomeotherexampleswhicharealsoresultedfromwatersuniquechemicalstructure?,Thesalinityoftheearthsoceansisabout3.5%.Whatdoesthismean?,Thereareaboutthirty-fivegramsofdissolvedsolidsandgasesinonekiloofwater.,Inwinterwaterinsomecontainersorsmallriversoftenfreezeswhilethatinseasnot?Canyouexplainit?,Thesalinityofseawatercanaffectthefreezingpointofwater.Seawaterhasalowerafreezingpoint,soevenwhenthetemperatureofseawaterfallsbelow0,seawaterisstillliquid.,Whatisdensity?,Densityistherelationshipbetween_and_andismeasuredinkg/m3,reading_.Thedensityofwateris_kg/m3.,mass,volume,kilospercubicmeter,1,000,Orderedmolecularstructureoffrozenwater(ice),Semi-orderedmolecularstructureofliquidwater,Doesitalsogoesforthephenomenonthaticelookslargerthanwaterdoes?,Whatdodifferentdensitiesintheoceanresultin?,Waterintheoceanisalwaysmoving.,Whatphenomenacanthisresulthelpusexplain?Pleasegiveexamples.,Oceanmotionhelpsmovenutrientsaroundandaddsenergytothemarineecosystems.Differentmarinecreaturesliveindifferentlevelsoftheocean.(Becauseofthefoodstheyneed,sunshineetc.),Readfollowingstatementandthinkwhatconclusionyoucandraw?Orwhatpropertydoesitreferto?,Itissaidthatamanof60kglosesabout1Lwaterthroughbreathandskinevaporation(皮肤蒸发)everyday.Inotherwords,539kcalheatisreleasedinthesetwoways.Ifsomuchheatwerekeptinhumanbody,itwouldraisebodytemperatureby9.Canyouimaginetheresult?,Waterhasarelativelyhighheatcapacityandcanaccommodatetheclimateautomatically.Itcanabsorbandreleasealotofheatwithoutbigchangesinitstemperature,thuscreatingastableenvironment.,Herearesomemorefamiliarphenomena,whatpropertyofwateraretheyrelatedto?,Thecoastalareasareoftenneithertoohotnortoocold.Icefloatsonwater.Whentheseawaterinacontainerisevaporated(蒸发),therewillbesomesaltleft.Irrigateinwintercanhelpraisethesoiltemperature.PeopleswimmingintheDeadSeafloa