SS-氯化物-硬度VIP专享VIP免费

悬浮物、氯化物、硬度时间安排•预习时，首先洗净SS测定需用的称量瓶，将滤膜置入，烘第一遍；再清洗其他玻璃器皿。•预习，绘制数据表格，考虑注意事项。•上课前，采集“若谷”学区前的湖水样品，每人装满1个矿泉水瓶，上课时带来。•上午上课时，先集中听讲解“称量”，然后分成小组称滤膜，或准备滴定。•集中听讲解3个实验。•分头做实验。2011年不用事前已经把膜烘过了2.4.DeterminationofSuspendedSolids•Purpose:Tounderstandtheprinciplesofweighingmethod,andoneofthesamplepretreatmentmethods,filtration,aswellastomasterthemethodsofmeasurementofsuspendedsolid.QuestionsWhatisSS?•Definition:remainedon0.45µmmembraneWhatisweighingmethod?•WeightdifferenceHowtoholdtheweighingbottle?•Donotdirecttouchit.Whatissamplepretreatment?Separationmethods:•Filtrationultra-filtration•Extraction•Centrifugation•Osmosis•Chromatography•ElectrophoresisKeypoints•Togettheconstantweight•Enoughdrytime•Enoughcoolingtime•Desiccator•Desiccant---Sigel2.5.DeterminationofChloride•Purpose:Tounderstandtheprincipleofchloridemeasurement,andtomasteroneofthevolumetricmethods,precipitationtitration.Whatistitration?•Oneofthevolumetricmethods,reactionoftitrantandtargetanalyte.Typeoftitration:Acid-baseRedox(reducing-oxidizing)ComplexationprecipitationProcedureoftitration1.Fillingtitrantsolution,adjustingzeromark.2.PutXXmLsamplesolutionintoaflask3.Addafewdropsofindicatorsolution4.Titratewithtitrantsolutionuntiltheendpoint5.Recordthevolumeoftitrantconsumed6.calculationprecipitationtitrationAg++Cl-AgClwhite,pKsp=9.742Ag++CrO42-Ag2CrO4reddish,pKsp=11.92Ag2CrO4ppt(moresoluble)formafterAgCl(lesssoluble)SuitablepHrange:6.5～10.51blankand2samplesforeachstudentNote:VblankV≒sampleColorturning:lightyellowgreentoreddishsamples•Dilutedseawatersamples•Tapwater•Titratetheblankfirst,forcomparingthecolor.2.6.DeterminationofTotalHardness•Purpose:Tounderstandtheprincipleofhardnessmeasurement,andtomasteroneofthevolumetricmethods,complexationtitration.Whatishardness?•TotalhardnessisthetotalconcentrationofCaandMginwater,whichincludescarbonatehardnessandnon-carbonatehardness.Whatistemporaryhardness?•CarbonatehardnessisequaltotheamountofCaandMgcarbonateorbicarbonateCa(HCO3)2CaCO3＋CO2＋H2OMg(HCO3)2MgCO3＋CO2＋H2OWhatishardness?Whatispermanenthardness?•non-carbonatehardnesscontainschloride,sulfate,ornitrate•cannotberemovedbyboilingcomplexationtitration1.EBT,ablueindicatorCa/Mg+EBT,formpurple-redcomplex2.TitratewithEDTACa/Mg-EBT,lessstableCa/Mg-EDTA,morestable3.AttheendpointCa/Mg-EDTA,colorlessFreeEBT,lightbluesamples3samplesforeachstudent•Tapwater•Drinkingwater•LakewaterNote:Ifthesamplevolumeisdouble,adddoublebuffer