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《无机化学 酸碱中和滴定的指示剂问题（indicator problems of acid-base neutralization titration in inorganic chemistry）》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。
1、无机化学酸碱中和滴定的指示剂问题（Indicatorproblemsofacid-baseneutralizationtitrationinInorganicChemistry）Neutralizationofacidandalkaliandselectionofindicatorfortitration(1)Phenolphthalein:acidalkalititration:colorfromredjustfadeAlkalinetitrationofacid:colorfromcolorlesst
2、olightred(2)MethylOrange:AcidTitrationofalkali:colorfromyellowtoorangeAlkalinetitrationofacid:colorfromredtoorangeGenerallydonotchooselitmusThechoiceofacidbaseneutralizationandtitrationindicatortwoInordertoreducethemethoderrorandmakethetitrationendpointeq
3、ualtotheequalpoint,itisnecessarytochoosetheappropriateindicator.Whenthestrongacidandweakbasearetitratedeachother,methylorangeshouldbeused.Strongandweakinteractionshouldbeusedintitration,phenolphthalein.Acidandalkalititrationcanbeusedeachother,methylorange
4、,canalsousephenolphthaleinasindicator.Notethatnotusinglitmusindicatortitration.Thereasonisthelitmuscolorrange(pH5.0~8)istoowide,thecolorchangeisnotobviousattheendoftitration,itisnoteasytoobserve.Selectionofindicatorforneutralizationtitrationofacidandalkal
5、ithreeThecommonlyusedindicatorisaweakacidorbase,suchasphenolphthaleinandmethylorangelacmus;organicacidcomplex.Themoleculesandionsoftheindicatorhavedifferentcolors.Theacidoralkalisolutioncanaffecttheionizationbalanceoftheindicator.Therefore,theindicatorwil
6、lshowdifferentcolorsintheacidoralkalisolution.Theselectionofindicatorsinneutralizationtitrationshouldconsiderthefollowingaspects:(1)Thenarrowerthecolorrangeoftheindicatoris,thebetterthepHchanges,andtheindicatorcanchangethecolor.Litmussolutionduetoawideran
7、geofcolor,andthechangepointwhenthecolorisnoteasytoobserve,sodonotuseinneutralizationtitration.(2)Itiseasytoobservethechangeofthecolorofthesolutionfromshallowtodeep,butitisdifficulttoobservethechangefromshallowtodeep.Therefore,theindicatorshouldbechosentoc
8、hangethecolorofthesolutionfromshallowtodeepattheendoftitration.Despitethestrongacidandstrongalkalineutralization,phenolphthaleinandmethylorangecanbeused,butwiththetitrationofacidalkali,andmethylorangeinalkali,etc.wh
