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1、高中化学58个精讲(33)盐类的水解(58lecturesonchemistryinseniorhighschool(33)hydrolysisofsalts)Highschoolchemistry58testsiteselaborate33.Hydrolysisofsalts1.reviewkeypointsHydrolysisprincipleof1.saltsanditsapplicationThemutualrelationandconservationprincipleofparticlesin2.solution2.
2、difficultiesfocus(1)hydrolysisessenceofsaltH2OH++OH-AB==Bn-+An+HB(n-1)-A(OH)nWhenthesaltABcanionizeweakacidanion(Bn-)orweakbasecation(An+),itcanbecombinedwithH+orOH-,whichisionizedbywater,toformelectrolytemolecules,thuspromotingthefurtherionizationofwaterTherelations
3、hipbetweenneutralizationandneutralization:Salt+wateracid+alkali(atleastoneofthemisweak)Therefore,salthydrolysisforthereversereactionofneutralizationreaction,butgenerallyneutralizationdegree,mostofthatistobecompletely,butthedegreeofhydrolysisofsaltsaremuchsmaller,so00
4、0reversereaction,hydrolysisoftheionreallyisaverysmallproportion.(two)hydrolysislawBriefly:thereisnoweakweaktohydrolysis,hydrolysisweakerhydrolysis,hydrolysisofallwhoisstrongwhowasweak,strongneutralConcretely:1.normalsaltsolutionStrongacidweakbasesaltisacidic.Strongal
5、kaliweakacidsaltisalkaline.Strongacid,strongalkaliandsaltareneutral.WeakacidalkalisaltisnotnecessarilySuchasNH4CNCH3CO2NH4NH4FAlkalineneutralacidityItdependsontherelativestrengthofweakacidsandbases2.acidsaltIfthereisonlyionizationwithouthydrolysis,itisacidic(e.g.,NaH
6、SO4)IfbothionizationandhydrolysisdependontherelativesizeofbothThedegreeofionizationismoreacidicthanthedegreeofhydrolysisThedegreeofionizationislessthanthedegreeofhydrolysis,andisalkalineIonizationandhydrolysisofstrongbaseweakacidsaltsA)expressedinHmAn-ionizationandac
7、idhydrolysisequilibriumacidsaltanion.Hm+1A(n-1)-+OH-HmAn-1+H2OHm-1A+H+(n+1)InhibitionofhydrolysisinhibitionionizationIncreasing[OH-]promotesionizationandpromotestheincreaseofwaterleaving[H+]CanonlyexistinacertainrangeofpHForexample,H3PO4anditsthreeanionscanbetransfor
8、medwiththechangeofsolutionpH:IncreasingpHvalueH3PO4H2PO4-HPO42-PO43-PHdecreaseThepHofthesolutionofcommonsaltAlkalinity:NaHCO3,NaHS,