chm 152ll the solubility product of calcium hydroxide：chm 152ll氢氧化钙溶度积

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1、CHM152LL:TheSolubilityProductofCalciumHydroxideIntroduction:Calciumhydroxide,Ca(OH)2,isconsideredaslightlysolublesubstanceinwater.Ca(OH)2(s)Ca2+(aq)+2OH-(aq)Ksp=[Ca2+][OH-]2Inthisexperiment,wewillmeasureandconcentrationofCa2+inasaturatedsolutionofCa(OH)2

2、andcalculatetheKsp,solubilityproductconstant,forCa(OH)2.WearegoingtoobtainasaturatedsolutionofCa(OH)2.ThenfilteroutthesolidCa(OH)2.The[Ca2+]willbeobtainedthroughtitrationwithasolutionofEDTA4-(ethylenediaminetetraacetate).EDTA4-andCa2+reacttoforthecomplex

3、ionCa(EDTA)2-,Ca2+(aq)+EDTA4-(aq)Ca(EDTA)2-(aq)TheindicatorEriochromeBlackT(EBT)changescolorinthepresenceofCa2+.WithoutCa2+,itisblue;withCa2+,itformsaredcomplexion.WhenEDTA4-reactswithalltheCa2+,theindicatorEBTloosesitCa2+andrevertsfromredbacktoitsorigin

4、alblue.ThiscolorchangewillindicatetheendpointwherealltheCa2+hasreactedwiththeEDTA4-.Atthispoint,wecancalculatethemolesofEDTAadded,themolesofCa2+itreactedwith,thus[Ca2+],[OH-]andKsp.Material:125mLbeaker125mLErleneyerflask10_mLpipetEBTindicatorsolutionSatu

5、ratedCa(OH)2solution___________MEDTAsolutionExperimentalProcedure1.Pour50mLofsaturatedCa(OH)2solutionintoa125mLbeaker.Donotshakeupthesolutionbottle.Itissaturatedandthereissolidonthebottom.2.FilteryourCa(OH)2solutionintoadry125mLErlenmeyerflask.3.Obtaina3

6、0mL(or50mL)beakertobeusedtocoveruptheErlenmeyerflaskwhenitisnotinuse.4.MeasurethetemperatureofthesolutionintheErlenmeyerflaskwithaclean,drythermometer.5.Rinseacleanburettewith5mLportionsofEDTAsolution.6.FilltheburettewiththeEDTAsolution.7.Pipet10mLofthef

7、ilteredCa(OH)2solutionintoanotherclean125mLErlenmeyerflask.Add2dropsofEBTindicator.8.TitratetheCa(OH)2solutionwiththeEDTAsolutionuntiltheindicatorchangesfromreddishtoapureblue.(Apurplishcolorisnottheendpoint,butitdoesshowthatyouareclosetotheendpoint.)9.R

8、epeatthetitration(steps7~8)twomoretimes.CHM152LL:TheSolubilityProductofCalciumHydroxideName____________________Section___Partner_________ExperimentalResults:TemperatureInitialBuretteReadingFinalBuretteReadingVolumeofEDTAso