chem 3024 - southern nazarene university：化工3024 -南拿撒勒大学

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1、Chem3024NotesonpHTitrationLabFall2004Page7Theory-ThetheoryforthisexperimentisChapter10ofyourtextbook.TheexperimentalprocedureisExperiments23-7fromthepublisher’swebsite.1{Acopyoftheexperimentalprocedureispartofthisdocument,pages3-4.}YouwillusetheVernie

2、rLoggerPro™apparatustoacquireandprocessthetitrationdata.Thefollowingarechangesandclarificationstotheabovecitedexperimentalprocedure.Replacetheplasticburetabovewithyourglassburet.Adjusttheflowto~1dropper2seconds.Theapproximatevolumeofadropis1/20mL,butt

3、aketheinitialandfinalburetreadingssoyoucancheckthiscalibration.Procedure1.YoudonotneedtostandardizethepHprobesforthisexperiment.2.DONOTdrythissamplebecauseitmaydecomposebyheating.Instead,storeitinyourdesiccatorinaweighingbottlewithitscapremovedtoatlea

4、st24hours.Yourunknownsampleiseitherapuresolidweakacidoraweakbase;thefirststepwillbetodecidewhichyoursampleis.Thisisaccomplishedbypreparingthesamplefortheroughtitrationasdescribedinstep3byweighingapproximately0.7g,(accuratelyweighedto±0.1mg.)ofyoursamp

5、leintoa400-mLbeakeranddissolvinginapproximately200mLofdeionizedwater.UsethepHprobetomeasuretheinitialpHofthesolution.(BesurethatthelevelofthesolutioncomesabovetheceramicplugofChem3024NotesonpHTitrationLabFall2004Page7thepHelectrode;ifnecessaryadddeion

6、izedwatertothesolutionofyoursample.)IfthepH<7,yoursampleisaweakacid;ifthepH>7,aweakbase.Ifyoursampleisaweakacid,yourwilltitratewith0.1000MNaOH(±0.0005M);ifaweakbase,thetitrantwillbe0.1000MHCl(±0.0005M).Thesesolutionsarepresentinthelabascommerciallypre

7、paredandstandardizedtitrantsolution.1.Carryouttheroughtitrationasdescribedinstep3oftheattachedprocedure,usingthesamplepreparedinstep2above.Thecomputerwillrecordthetitrationdata.Onthefirsttitration,besuretocontinueuntilthepHis~12sothatifyoursampleispol

8、yproticyoucanseebothequivalencepoints.2.Basedonthevolumeoftitrantrequiredfortheroughtitrationinstep3,adjustyoursamplesizeforsubsequenttitrations,steps4and5ofthetextbookprocedure,soastocompletethetitrationwellpasttheendpointwithatotalvolumeofbe