空间相图和vapor gas释义.pdf

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1、Waterspacephasediagram(P-V-T)PhasediagramVaporvsGasAgasreferstoasubstancethathasasingledefinedthermodynamicstateatroomtemperaturewhereasavaporreferstoasubstancethatisamixtureoftwophasesatroomtemperature,namelygaseousandliquidphase.Thisalsomeansthatavaporisasubstancethathasexperien

2、cedsomesortofphasechangeatroomtemperature.Agasisasubstancewhosemoleculesareinconstantfreemotionpasteachotherandcanbecompressed,whichcanalsobereferredtoasacompressiblefluid.Whennoliquidorsolidcanformatthetemperatureofthegasitiscalledafixedgas.Itisworthnotingthatwhenreferringtothefo

3、urstatesofmatterthereisa‘gasphase’whichdoesnotnecessarilyrefertoagasasadistinctelementbutratherrepresentsdifferencesininterrelationshipsofmolecules.Agashasitssinglegasparticlesvastlyseparated,makingagasinvisibletotheeye.Whenasubstanceisatatemperaturebelowitscriticaltemperatureitis

4、ina‘gasphase’andthereforewillbeavapour.Avapourcanco-existwithaliquidorsolidwhentheyareinequilibriumstate.Thereforefromthiswecaninferthatavapourisagasstateofasubstanceatatemperaturewhereitcanco-existwithitsliquidorsolidstatesoforaliquidorsolidtobecomevapouritdoesnothavetofirstboil.

5、Itisalsoofparamountimportancetonotethatvapourisaresultofthetwotypesofvaporizationofaliquidwhichareboilingandevaporation,thetransitionfromliquidphaseto‘gasphase’.Evaporationoccursatthesurfaceoftheliquidwhenitstemperatureisbelowtheboilingtemperatureatagivenpressure.Boilingoccursbelo

6、wthesurfaceoftheliquid.Summary:1.Agashasonedefinedstateatroomtemperaturewhereasavapourisasubstancethatisingaseousandliquidequilibriumatroomtemperature,atagivenpressure.Agascanalsorefertoasingleelementofmatterwithitsownuniquephysicalandchemicalproperties,forexampleoxygen,nitrogenan

7、dneon.2.Becausevapourisactuallythegaseousstateofanelement,vapourparticleswillbeofasingleelementandmayhaveadefiniteshapewhereasgasparticleswhenobservedundermicroscopicviewdonothaveadefiniteshapeandwillbeacollectionofatoms,ions,electronsandmolecules.Howeverbothgasandvapourparticlesa

8、reinarandommotion,collidingwithea