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ID:50166179
大小:1.21 MB
页数:16页
时间:2020-03-09
《应用化学专业英语 教学课件 作者 黄忠 谢普会 付颖 主编lesson 13 volumetric analysis and qualitative.ppt》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、Lesson13VolumetricAnalysisIntroductionTheEquipmentTheProcessCalculationsIntroductionOfteninchemistryweneedtoworkouttheconcentrationofasolution.Thereareanumberofmethodswecoulduse,buttheyallinvolveworkingouttheamountofthesubstanceinacertainvolume.Volumetricanalysisinvolvesusingvolumesofliquidstoanaly
2、seaconcentration.Todothisweneedthefollowingthings:Achemicalofaknownconcentrationthatwillreactwithour‘unknown’concentrationchemicalAnindicatorthatwilltelluswhenallthechemicalhasbeenreactedAnumberofpiecesofequipmentthatwecanusetomeasurevolumeaccuratelyTheEquipmentVolumetricanalysisinvolvesafewpieceso
3、fequipmentthatyoumaynothaveseenbefore:Pipette–formeasuringaccurateandprecisevolumesofsolutionsBurette–forpouringmeasuredvolumesofsolutionsConicalflask–formixingtwosolutionsWashbottles–thesecontaindistilledwaterforcleaningequipmentFunnel–fortransferofliquidswithoutspillingVolumetricflasks–aflaskused
4、tomakeupaccuratevolumesforsolutionsofknownconcentrationTheProcess-PreparationTwosolutionsareused:Thesolutionofunknownconcentration;Thesolutionofknownconcentration–thisisalsoknownasthestandardsolutionWriteabalancedequationforthereactionbetweenyourtwochemicalsCleanallglasswaretobeusedwithdistilledwat
5、er.ThepipettesandburetteswillberinsedwiththesolutionsyouareaddingtothemProcess–TheSetupTheburetteisattachedtoaclampstandaboveaconicalflaskTheburetteisfilledwithoneofthesolutions(inthiscaseayellowstandardsolution)Apipetteisusedtomeasureanaliquotoftheothersolution(inthiscaseapurplesolutionofunknownco
6、ncentration)intotheconicalflaskPrepareanumberofflasksforrepeattestsLast,anindicatorisaddedtotheconicalflaskProcess–TheTitrationReadtheinitiallevelofliquidintheburetteTurnthetaptostartpouringoutliquidoftheburetteintotheflask.Swirltheflaskcontinuously.Whentheindicatorbeginstochangecolourslowtheflow.W
7、henthecolourchangespermanently,stoptheflowandreadthefinalvolume.Thevolumechangeneedstobecalculated(andwrittendown).ThisvolumeiscalledatitreRepeatthetitrationwithanewflasknowthatyouknowthe‘rough’volumerequir
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