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1、无机化学酸碱中和滴定的指示剂问题（Theindicatorofacid-baseneutralizationinInorganicChemistry）Oneofthechoiceofacid-baseneutralizationandtitrationindicators(1)Phenolphthalein:acidalkalititration:colorfromredjustfadeAlkalineacid:colorfromcolorlesstolightred(2)MethylOrange:whenacidisusedtotitratebases:t
2、hecolorisyellowtoorangeAlkalineacid:thecolorisredtoorangeGenerallydonotchooselitmusThechoiceofacid-baseneutralizationandtitrationindicatortwoInordertoreducethemethoderrorandmaketheend-pointoftitrationcoincidewiththeequalpoint,theappropriateindicatorshouldbechosen.Whenthestrongacida
3、ndweakbasearetitratedeachother,methylorangeshouldbeused.Strongandweakinteractionshouldbeusedintitration,phenolphthalein.Acidandalkalititrationcanbeusedeachother,methylorange,canalsousephenolphthaleinasindicator.Notethatnotusinglitmusindicatortitration.Thereasonisthelitmuscolorrange
4、(pH5.0~8)toowide.Thechangeofcolorattheendoftitrationisnotobvious.Itisdifficulttoobserve.ThechoiceofindicatorforneutralizationtitrationofacidandbasethreeThecommonlyusedindicatorisaweakacidorbase,suchasphenolphthaleinandmethylorangelacmus;organicacidcomplex.Themoleculesandionsofanind
5、icatorhavedifferentcolors,andtheacidorbasesolutioncanaffecttheionizationbalanceoftheindicator,sotheindicatorwillshowdifferentcolorsintheacidoralkalisolution.Thechoiceofindicatorsinneutralizationtitrationshouldtakethefollowingaspectsintoconsideration:(1)Thenarrowerthecolorrangeofthe
6、indicator,thebetterthepH,andtheindicatorchangesthecolor.Litmussolutionduetoawiderangeofcolor,andthechangepointwhenthecolorisnoteasytoobserve,sodonotuseinneutralizationtitration.(2)Itiseasytoobservethechangeofthecolorofthesolutionfromshallowtodeep,butitisdifficulttoobservethechangef
7、romshallowtodeep.Therefore,theindicatorshouldbechosentochangethecolorofthesolutionfromshallowtoshallowattheendofthetitration.Despitethestrongacidandstrongalkalineutralization,phenolphthaleinandmethylorangecanbeused,butwiththetitrationofacidalkali,andmethylorangeinalkali,etc.whenrea
8、chthepointwhenthecolorofth
