2.1Different-types-of-substance课件

2.1DifferenttypesofsubstanceChapter2Thenatureofmattersolidliquidgasmatter:anythingthathasmassandtakesupspacethreephysicalstates:solidliquidgasSolidsDefiniteshapeDefinitevolumeParticlesarepackedtightly,fixedParticlesmoveveryslowlyIndefiniteshape,definitevolumeTaketheshapeofcontainerParticlesareclosetogether,butmobileParticlesmoveslowlyLiquidsGasesIndefiniteshapeIndefinitevolumeTaketheshapeandvolumeofcontainerParticlesarefarapartParticlesmovefastLearningCheckMatch:(1)solid,(2)liquid,or(3)gas.____A.Hasadefinitevolume,butshapeofthecontainer.____B.Itsparticlesaremovingrapidly.____C.Fillsthevolumeofacontainer.____D.Particlesareinafixedstructure.____E.Particlesareclosetogether,butmobile.(2)(1)(3)(3)(2)pressuretemperatureChanginginphysicalstatesolid/liquid/gasliquid(slightly)/gasChanginginphysicalstatetherearethreedifferentphysicalstatesinwhichasubstancecanexistheatenergysolidtheparticlesvibratemorealiquidisformedheatenergymeltingpointChanginginphysicalstateMelting:whenasolidisheated,itsparticlesgetmoreenergyandvibratemore.Thismakessolidexpand.Atmeltingpoint,theparticlesvibratesomuchthattheybreakawayfromtheirpositions.Thesolidturnsliquid.meltingfreezingmeltingpoint(m.p):thetemperatureatwhichapuresubstanceturnstoaliquidiscalledmeltingpoint.freezingpoint(f.p):ifaliquidiscooleddown,itiscalledfreezingpoint.slowmovingparticlesinliquidtheparticlesmovefastertheparticlesgetenoughenergytoescapeheatenergyheatenergymeltingpointBoiling:whenaliquidisheated,itsparticlesgetmoreenergyandmovefaster.Theybumpintoeachothermoreoften,andbouncefurtherapart.Thismakestheliquidexpand.Atboilingpoint,theparticlesgetenoughenergytoovercometheforcebetweenthem.Theybreakawaytoformagas.pressureincreases,boilingpointincreasestakesplacefromthesurfaceofliquidThelargerthesurfacearea,thefasterthelipuidevaporatesEvaporationcondensation(liquefaction)evaporationcondensationisthereverseofgasliquidsublimationthedirectchangeofstatefromsolidtogasThemeltingandboilingpointsofsomecommonchemicalsubstancehighersummarysolid→liquidsolid→gasgas→liquidliquid→gasliquid→solidmeltingfreezing(solidification)evaporation(vaporisation)condensation(liquefaction)sublimationpuresubstanceApuresubstancehasnoparticlesofanyothersubstancemixedwithit.Anunwantedsubstance,mixwiththesubstanceyouwant,iscalledimpurity.impurityIsitanimpurity?Youmixinstantcoffeewithwater,tomakeacupofcoffee.Isthecoffeeanimpirity?ExplainHowcanyoutellifasubstanceispure?Apuresubstancehasadefinite,sharp,meltingpointandboilingpointcheckmeltingandboilingpointsThemeltingandboilingpointsnolongertakeplacesharply,butoverarangeoftemperature.Themoreimpuritypresent,thebiggerthechangeinmeltingandboilingpoints,andthewiderthetemperaturerangeoverwhichthesubstancemeltsandboils.Thepresenceofanimpurtityinasubstance:lowersthemeltingpointraisestheboilingpoint??Apparatusformeasuringthemeltingpointwaterbath:usedformeltingpointbelow100℃oilbath:usedformeltingpointabove100℃puresubstance：thesolidismelting，thetemperaturestopesrising.Itwillonlybegintoriseagainwhenallthesubstancehasmelted.mixture:thesolidwaxmeltingoverarangeoftemperatureThecoolingcurveforasubstanceThetemperaturestaysconstantwhilethegascondenses,andwhiletheliquidfreezes.Acoolingmixtureoficeandsaltbeusedtolowertheterperaturebelow0℃MixtureAmixturecontainsmorethanonesubstance.Thesubstancesarejustmixedtogether,andnotchemicallycombined.Sugarthatdissolvesinthewateriscalledsolute.+→Theliquidinwhichthesoliddissolvesiscalledthesolvent.=solute+solventsolutionNoteverythingdissolvessoeasily.supensionprecipiationreactionsolution:solid+liquidgas+liquidliquid+liquid