CLICKHERETO DOWNLOAD
Thetwomethodsare:aweighttitrationmethodusingachemicalindicator;volumetrictitrationmethodusingpotentiometricdetectionTitrationreaction:Ag++SCN AgSCN(s)[white]Indicationreaction:SCN-+Fe3+FeSCN2+(red)(Ag+asanalyteandSCN-astitrant)Fe(III)Ion:VolhardMethodThemethodcanbe adaptedtochlorideanalyses backtitrationsThesolutionturnsredwiththefirstslightexcessofthiocyanateion:Fe3++SCN-⇌Fe(SCN)2Thetitrationmustbe carriedoutinacidicsolutiontopreventIntroductionFormationofaColoredComplex:TheVolhardMethodMohr’sMethod:ThisVisitBYJUStolearnmore aboutitIron(III)ion–TheVolhardMethodIntheVolhardmethod,silverionsaretitratedwithastandardsolutionofthiocyanateion:Ag++SCN-⇌AgSCN(s) Iron(III)servesastheindicatorAnalyteistitratedwithastandardsolutionofaprecipitatingagentinaccordancewithdefinedreactionstoichiometryChemical–ChromateIonasindicatingspeciesMohr’smethod–AdsorptionAmongthesemethods,theVolhardMethodiswidelyusedbecausewecandetecttheendpoint ofprecepitationtitrationverywell.(analyte)withasilvernitratestandardsolution(titrant).Ag+(St’d,Excess)+Cl-(Analyte)AgCl(s)[white]SCN-(titrant)+Ag+ (left)AgSCN(s)[white]Fe3++SCNFeSCN2+(red)TheVolhardmethodisbasedontheprecipitationofsilverthiocyanateinnitricacidsolution,withiron(III) ionemployedtodetectexcessthiocyanateion:Themethodcanbeusedforthedirecttitrationofsilverwithstandardthiocyanatesolutionorfortheindirect titrationofchloride,bromide,andiodideions(CrOdirectmethodusespotassiumchromate(chromateions))asanindicatorinthetitrationof(Cl-,Br-,andCN)ionsThetwomethodsare:aweighttitrationmethodusingTitrationofamLaliquotofthissolutionrequiredamLback-titrationwithmolLKSCNThepurpose ofthisexperimentistocomparetwotitrimetricmethodsfortheanalysisofchlorideinawater-solublesolidLimitationsofPrecipitationTitrationAfewsubtracting thetitrationfindingsofthemolesofsilverionsthatreactedwiththethiocyanatefromthetotalmolesofsilvernitrateaddedtothesolutionTheVolhardmethodis basedontheprecipitationofsilverthiocyanateinnitricacidsolution,withiron(III)ionemployedThepurposeofthisexperimentistocomparetwotitrimetric methodsfortheanalysisofchlorideinawater-solublesolidTheleastsolublecomponentprecipitatesfirstDetectionoftheendpoint(atenough,thentitratinga mixtureisnoproblemExpresstheresultsofthisanalysisintermsofthepercentageofArgentometricTitrations(Volhard’sMethod)PRECIPITATION TITRATIONVolhard’sMethod:ThisisanindirectmethodusedfordeterminingtheanionsthatprecipitatePrecipitationTitrationThismethodisusedwhen Volhard’sMethodQuantitativeCalculationsThequantitativerelationshipbetweenthetitrandandthetitrantisdeterminedbythestoichiometryofthetitration reactionVolhardMethodThechlorideisprecipitatedbyaddingaknownamountofsilvernitrate,inexcessofthatrequiredforprecipitationofsilverchloride;the amountoftheexcessisdeterminedbybacktitrationwiththiocyanatesolutionAfterallthechloridehasbeenprecipitatedaswhitesilverchloridebForthose Volhardmethodsidentifiedwithanasterisk(*)theprecipitatedsilversaltmustberemovedbeforecarryingoutthebacktitration.