Chapter 102 Mole-Mass Mole-Volume relationships：102章摩尔质量摩尔体积的关系

Ch.10.2Mole-Massand

Mole-VolumeRelationshipTheMole-MassRelationshipMolarmassofanysubstanceisthemassingramsofonemoleofthatsubstance.Appliestoatoms,molecules,formulaunits,etc.Withgases,youmustbeclearastowhetherthegasisatomicormolecular(Ovs.O2).Usethemolarmassofasubstancetoconvertbetweenthemassofasubstanceandthemolesofasubstance(molarmass=onemole).mass(grams)=#ofmolesxmass(grams)/molesEx:molarmassofNaClis58.5g/moles.Whatisthemassof3.00molesofNaCl?3.00molx58.5g/mol=176gramsPractice—molestomassWhatismassof9.45molesofaluminumoxide?Whatisthemassof4.52x10-3molesC20H42?Whatisthemassof2.50molesofiron(II)hydroxide?Practice—masstomolesMoles=mass(grams)x1mole/mass(grams)Howmanymolesin92.2gramsofiron(III)oxide?Howmanymolesin3.70x10-1gofboron?Howmanymolesin75.0gofdinitrogentrioxide?Themole-volumerelationshipOnemoleofanygas,atstandardtemperatureandpressure,willalwaysoccupythesamevolume.Reasonisthat,inagas,theatomsormoleculesaresofarapart,thatthesizeoftheindividualatomsormoleculesisinsignificantcomparedtothedistancesbetweentheatomsormolecules.StandardTemperaturePressureSTPTemperature:0oCelciusPressure:1atmosphere(atm)or101.3kiloPascal(kPa)Onemoleofanygas(6.02x1023RP)atstandardtemperatureandpressure(STP)willalwaysoccupy22.4liters.

PracticeHowmuchvolumedoes0.5molesofoxygentakeup?Multiply:0.5molesx22.4l/mole=11.2lHowmanymolesN2arefoundin50.00lofgas?Calculate:50.00lx1mole/22.4l=2.2molesGoToMoleIsland!!!

VolumeofGas

multiplymolesbydividevolume22.4l/molesby22.4l/mole

DividemassbyMolemultiplymolewithMolarmass6.02x1023

multiplymoles withmolarmassdivideRPs

Representative

Mass6.02x1023

ParticlesRP

PracticeProblem1Findthenumberofmoleculesin50.8litersofO2FirstwritepathwayVolume→moles→RP50.8lx1mole/22.4l=2.27moles2.27molesx6.02x1023RP/mole=1.36x1024O2Howmanyatoms?2atoms/RPx1.36x1024RP=2.42x1024AtomsOxygenPracticeProblem2Findthevolumeof500gofPO2Mass→moles→volumeMolarmassofPO230.97+(2x16.00)=62.97g/molmoles:500gx1mole/62.97g=7.94molesVolume:22.4moles/literx7.94moles=177.8litersPracticeProblem3Howmanyatomsarein400gofC2(OH2)4Mass→moles→RP→AtomsMolarmass:2x12.01+4x(16.00+2x1.01)=96.10g/mol#ofatoms:144