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1、TheBehaviorofGases气体特性BriefWhatisavacuum?Inthedictionary，theword“vacuum”isdefinedasan“emptyplace,aplacedevoidofmatter.”However,likethedefinitionof“absolutezero”,itmaybeimpossibletoproduceaconditiontosatisfiesthisdefinition.Inapracticalsense,avacuumisdefinedas“aspacefilledwithgasatapr
2、essurelessthanatmosphericpressure.”Fromthedefinition,practicalvacuumisasituationoflessgases,so,thefirststepinunderstandingvacuumistounderstandlowgasesbehaveandhowtheyaredescribed.CharacteristicsofaGasAsampleofagivenkindofgasiscompletelydescribedwhenthevaluesoffourquantitiesthatrelate
3、toitareknown.Thesequantitiesareitspressure,volume,temperature,andtheamountofgasinthesample.PressurePressureisdefinedastheforceperunitareathatagasexertsonthewallsofitscontainer.Invacuumwork,pressureismeasuredinTorr,Pa,atm,mmHgandsoon.1atm=101325Pa=760mmHg=760TorrVolumeVolumeissimplyam
4、easurementofthespaceagastakesup.Itismeasuredinliters,aliterisslightlymorethanaquart(夸脱，英美计量单位).TemperatureInvacuumwork,temperatureismeasuredineitherdegreescentigrade(℃)ordegreesabsolute(K,),bothofwhichhavethesamescaledivisions.Theyareconvertedbytheequationbelow.Absolutezero=-273℃=0K，
5、T(℃)=t(K)+273KAmountsofGasTheamountsormassofgasinagivensampleismeasuredingrammoles.Agrammolescontainsroughly600thous--andbillionbillionmolecules.Inthisbookgrammoleswillbereferredtosimplyasmoles.Ithasbeenfoundthatonemoleofanygas,atatemperat--ureof0℃,andapressureof760Torr(101325Pa)occu
6、p--iesavolumeof22.4liters.Tips:0℃and760Torrpressure(101325Pa)areknownasstandardtemperatureandpressureandareabbreviatedas“S.T.P.”`TheGasLawsTherearecertainrelationshipsthatholdamongthefourquantitiespressure,volume,temperature,andamountofgas;usingtheserelationships,itispossibletofindth
7、evalueofanyquantityifweknowthevaluesoftheotherthree.Therearefours“laws”governingthebehaviorofgasesthatweshallconsider:Boyle’slaw,theAvogadrolaw,Charles’law,andtheidealgaslaw.Boyle’slawCertainmassofthegas,theproductofthegaspressureandvolumeisconstantataconstanttemperature.Thiscanbesum
8、m--arizedina
