悬浮物和氯化物

悬浮物、氯化物时间安排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2个实验。分头继续做实验。2.4.DeterminationofSuspendedSolidsPurpose:Tounderstandtheprinciplesofweighingmethod,andoneofthesamplepretreatmentmethods,filtrationTomasterthemethodsofmeasurementofsuspendedsolid.QuestionsWhatisSS?Definition:remainedon0.45µmmembraneWhatisweighingmethod?WeightdifferenceHowtoholdtheweighingbottle?Donotdirectlytouchit.Whatissamplepretreatment?Separationmethods:Filtration，ultra-filtrationExtractionCentrifugationOsmosisChromatographyElectrophoresisKeypointsTogettheconstantweightKeepenoughdrytimeKeepenoughcoolingtimeDesiccatorDesiccant---Sigel(blue-red)2.5.DeterminationofChloridePurposeTounderstandtheprincipleofchloridemeasurementTomasteroneofthevolumetricmethods,precipitationtitration.Whatistitration?Oneofthevolumetricmethods,reactionoftitrantandtargetanalyte.Typeoftitration:Acid-baseRedox(reducing-oxidizing)ComplexationPrecipitationProcedureoftitration1.Fillingtitrantsolution,adjustingzeromark.2.PutXXmLsamplesolutionintoa(conical)flask3.Addafewdropsofindicatorsolution4.Titratewithtitrantsolutionuntiltheendpoint5.Recordthevolumeoftitrantconsumed6.CalculationprecipitationtitrationAg++Cl-AgClwhite,pKsp=9.742Ag++CrO42-Ag2CrO4reddish,pKsp=11.92Ag2CrO4ppt(moresoluble)formafterAgCl(lesssoluble)SuitablepHrange:6.5～10.51blankand2samplesforeachstudentNote:Vblank≒VsampleColorturning:lightyellowgreen(fromindicator)toreddish(fromAg2CrO4)samplesDilutedseawatersamples(dilutionratio)TapwaterBlank:purewaterTitratetheblankfirst,forcomparingthecolor.Attention!!TheleftAgNO3solutionintheburetteshouldberecycled.