CHEM108LABORATORY7DETERMINATIONOFTHEMOLARMASSOFAVOLATILELIQUIDMaterialsNeededClean250mLErlenmeyerflasks600mLbeakersBoilingchipsAluminumfoilRulersScissorsPinsRingstandandclampsHotplatesUnknownsamples(methanol,hexane,decane)icmoleculartheoryofgases,moleculesofagashavenointeractions(eitherattractionsorrepulsions)betweenthem,,,:Boyle’sLawstatesthatthepressureandvolumeofafixedamountofgasareinverselyproportionalwhenthetemperatureisheldconstant:Visproportionalto1/P(atsameTandn)Charles’Lawstatesthatthevolumeandtemperatureofafixedamountofgasaredirectlyproportionalwhenthepressureisheldconstant:VisproportionaltoT(atsamePandn)Avogadro’sLawstatesthatthenumberofmolesofagasisdirectlyproportionaltothevolumeofthatgaswhenthepressureandtemperatureareheldconstant:Visproportionalton(atsamePandT)bined,thefollowingrelationshipresults:V=(nRT)/PorPV=nRTThethirdarrangementistheIdealGasLaw,inwhichPisthepressure,VistheVolume,Tisthetemperature(inKelvin),.Ifwerearrangetheidealgasequation,wefindthat:n=PV/RTBecausethenumberofmoles,n,isalsogivenbyn=m/M wheremisthemassofthegasandMisthemolarmassofthegas,wecansubstitutetheabove
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