5. atoms,molecules and stoichiomitry Alevel 考试化学课件.pptx
Chapterthree
Atoms,moleculesandstoichiometryCalculationinvolvingconcentrationsandgasvolume
ConcentrationofsolutionsUnit:moldm-31moldm-3iswhenonemoleofacompoundisdissolvedinasolventtomakeonecubicdecimetreofsolutionConcentrationinmoldm-3havebeenexpressedasmolarities.Forexample,twomoldm-3aqueoussodiumhydroxideis2Maqueoussodiumhydroxide,Misthemolarityofthesolution
Titration:Awayofmeasuringquantitiesofreactants,andcanbeveryusefulindeterminingtheprogressofareactionIntitration,therearefivethingsyouneedtoknowThebalancedequationforthereactionshowingthemolesofthetworeactantsThevolumeofthesolutionofthefirstreagentTheconcentrationofthesolutionofthefirstreagentThevolumeofthesolutionofthesecondreagentTheconcentrationofthesolutionofthesecondreagent
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GasvolumeIn1811,Avogadrodiscoveredthatequalvolumesofallgasescontainthesamenumberofmolecules(volumeundersameconditionsoftemperatureandpressure)Atroomtemperatureandpressure,onemoleofanygasoccupiesapproximately24.0dm3Wecanusereactingvolumesofgasestodeterminethestoichiometryofareaction.Theexperimentmustbecarriedoutunderthesameconditionoftemperatureandpressure
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SummaryUnitsofconcentration:moldm-3,gdm-3TitrationCalculationformstoichiometricratioGasvolume24.0dm3underroomtemperatureandpressureCalculationformvolumeratio