分析化学第六章配位滴定法课件.ppt

1、NCH2CH2NCH2COOHCH2COO-H+H+HOOCH2C-OOCH2CHHEDTA（乙二胺四乙酸）结构H4YH6Y2+2 H+四元酸六元酸两个氨氮四个羧氧双极离子H6Y2+H+H5Y+H5Y+H+H4Y H4Y H+H3Y-H3Y-H+H2Y2-H2Y2-H+HY3-HY3-H+Y4-最佳配位型体最佳配位型体水溶液中七种存在型体水溶液中七种存在型体稳定常数 KMYM YMY一级稳定常数 KMLM L1二级稳定常数 KMLML L22级稳定常数nKMLMLLnnn1一级累积稳定常数 11KMLML二级累积稳定常数 21222K KMLM L总累积稳定常数 nnnnK KKMLM L12

2、M +YMY主反应：副反应：H+HYH2YH6YLOH-MLML2MLnMOHM(OH)22M(OH)nNNYMHYM(OH)YOH-H+辅助配位效应羟基配位效应酸效应干扰离子效应混合配位效应M+YMYH+HYH2Y酸效应引起的副反应主反应H6YH+H+H+44526)(YYYHYHYYHY654321156621)(,1aaaaaaaaaaYYHYKKKKKKKHHKKK654321654321156)(aaaaaaaaaaaaaHYKKKKKKKKKKKKKHH123456661aaaaaaaKKKKKKHKH，配合物稳定；副反应越严重，）（112)(4)(HYHYHYpHpHYHpH6.

3、69.06.107.275.224.634.10306.107.275.224.634.102507.275.224.634.102075.224.634.101524.634.101034.105)(101010101010101010101010101HYLmolYYHY/1071002.0 960.6)(M+YMYNNY主反应干扰离子效应引起的副反应 NKYNYYYYNYNY1)(副反应越严重,)(YNY 44526YNYYYHYHYYY444444526YYYYNYYYYHYHYY HY N()()1M+YMY主反应辅助配位效应引起的副反应LMLML2MLnLLL MMLMMLMMLM

4、LMMMnnLM1)(nnLKKKLKKLK2122111 nnLLL2211高，副反应程度，）（LML)()(OHMLMOHLMnmMMMMLMLMAMAMMMLMLMMAMAMMMnmMM LM A()()1500.446.900.331.700.281.400.137.2)(101.3101010101010101013NHZn5)()0(105.24.5lg11OHZnHZnpH，5)()(106.513OHZnNHZnZnKMHYMY HMHYKM OH YMY OHM OH Y()()MY HMHYMYMYMYMHYMYKH()1MY OHM OH YMYMYMYM OH YMYK

5、OH()()()1副反应系数MYMYYMMYKMY稳定常数MYYMMYMYKKlglglglglgYMMYKlglglg MMYYLMHY）（）（和由 YMMYMYYMMYMYKYMMYK，配合物稳定性，MYYMK YMMYKMY条件稳定常数)()(lglglglg3HYNHZnZnYZnYKK49.5lg101.3)(5)(33NHZnNHZn28.1lg109)(28.1)(HYHYpH50.16lgZnYK查表73.928.149.550.16lgZnYK所以45.6lg551.13lg2）（）（时，；时，查表可知：HYHYpHpH50.16lgZnYK查表）（HYZnYZnYKKlgl

6、glg99.251.1350.16lg2ZnYKpH时，05.1045.650.16lg5ZnYKpH时，YYMMVCEDTAVCM滴入体积为浓度为体积为浓度为）（）（根据2 1 YMYYYMMMVVVCMYYVVVCMYMMBE)4()3(MVVVCVVVCYMVVVCMYYMMMYMYYYMMM)5(YMMYKMY又0)1(5432MYMMMYYMYYMMMYCVVVMKVVVCVCMK）代入（）和（将（配位滴定曲线作图以 MVY69.73.5滴定突跃：021 21,2SPMSPSPMYMSPMYMCMMKCCVVSP直接代入滴定曲线方程时等浓度滴定达2411 MYSPMMYSPMMYSP

7、KCKCKMSPMMYSPpCKpMlg21!关键的计算是选择指示剂的时注：SPpMSPLmolNHLmolCSPSPCu/10.0/100.132，时，53523231)(13NHNHNHNHCu36.99586.12432.13302.11298.731.410108.110.01010.01010.01010.01010.0101)(36.97.1)(1010,10OHCuOHCupH忽略时45.0lg10）（时又在HYpH)()(3lglglglgNHCuHYCuYCuYKK99.836.945.080.1850.5)99.800.2(21)lg(21CuYSPCuYKpCpCu0lg

8、2MgMg时，已知滴定25.845.07.8lglglg）（HYMYMYKK13.5)25.800.2(21)lg(212MgYSPMgKpCpMg大大一定时，pMCKMMYpMKCMYM大一定时，pMKKMYMY，)(pMKpHMYHY小，大小，小小，大大，）（pMKCMYLMLMYK个单位倍110pMCM个单位倍110pMKMYMYK)(HInMInMInKInMMInKM没有副反应)(lglg lglgHInMInMInKInMInpMK)(HInMMInMInKInMMInKM有副反应)(lglglg lglgHInMMInMInKInMInpMK 混合色变色点时：InMIn无副反应）

9、MKKpMpMHInMInMIntep(lglglg)(有副反应）（MKKpMpMpMMHInMInMMInMtteplglglglglglg)(高，指示剂灵敏度，tpMpH%100%100%100%100%100%spMepepspMepepspMepMepYspspMepepMepepYspMepYCMYCMMYYMYCCCVCVCVCnnTEspeppYpYpY speppMpMpM10 pMspepMM10 pYspepYY%10010 10%spMpMsppYspCMYTEepspepMYspMYspspMYMYKKMYSP )()(又时epepepspspspYMMYYMMY pY

10、pMYYMMepspspep%1001010%spMMYpMpMCKTE MYspMspspKCYM又有2MspMspepCCpMpMpM等浓度滴定时注：%100)1010(%spMpMpMspCMTEpMCKspMMY和，终点误差取决于小；大，大，%TECKspMMY大大，%TEpM4.2lg45.0lg10)(）（，时，已知OHZnHYpH68.65446.9331.7261.437.2)(101078.420.01020.01020.01020.01013NHZn68.64.268.6)()(101101013OHZnNHZnZn37.968.645.05.16lglglglg)(ZnH

11、YZnYZnYKK69.5)237.9(21)(lg21spZnZnYsppCKpZn2.12lg10EBTZnepKpZnpH时查表可知52.568.62.12lglglgZnEBTZnEBTZnepKKpZn17.069.552.5speppZnpZnpZn%02.0%10010101010%37.900.217.017.0TE 45.0lg10）（时，已知HYpH69.10lgCaYK且24.1045.069.10lglglg)(HYCaYCaYKK12.6)224.10(21)(lg21spCaCaYsppCKpCa4.5lgEBTCaK已知6.1lg10）（时，又HEBTpH8.36

12、.14.5lglglg)(HEBTEBTCaEBTCaepKKpCa32.2speppCapCapCa%5.1%10010101010%24.1000.232.232.2TE 2Mg如果滴定的是7.8lgMgYK25.845.07.8lglglg)(HYMgYMgYKK则1.5)225.8(21)(lg21spMgMgYsppCKpMg0.7lgEBTMgK又4.56.10.7lglglg)(HEBTEBTMgMgYepKKpMg3.01.54.5speppMgpMgpMg%11.0%10010101010%25.800.23.03.0TE%1.0%2.0TEpM，6lg106MYspMMYs

13、pMKCKC或满足6lgMYspMKC准确滴定判别式8lg/01.0MYspMKLmolC满足当)()(lglglglgOHMHYMYMYKK)(lglglgHYMYMYKK由8lg/01.0MYspMKLmolC时，满足已知查表求得最高酸度）（8lglgMYHYK)(lglglgMYMYHYKK%TEKMYHY，注：超过最高酸度，）（nMOHSPMKOH)(%TEKMYOHM，注：低于最低酸度，）（pOHpH14最低酸度0 SPtpMpMpM满足)(lglglgHInMInMIntKKpMSPMMYSPpCKpM lg21值为最佳酸度对应的pHpMpMsptMHInMInMttKpMpMlg

14、lglglg)(或MNKKNYMY存在下准确滴定有可能在NMKKNYMY，应先掩蔽无法准确滴定NYMYKK前提：YMYMYKKMlglglg副反应不考虑1)()(NYHYY定值1)(NKNKYNYYNYNYNY)()()(HYYNYHYMNKKHYMYMY，相当于滴定忽略)(lglglg)()()(NYYNYHY忽略酸效应NNNYMYNYMYMYpCKCKKKKlglglglglglg)(2.0%10.0%pMTE，若6lgMYspMKC须满足NMCC若6lgK分步滴定判别式则NNYMYspMMYspMNYMYMYCKKCKCKKlglg)(又NMCC10若5lgK分步滴定判别式则6lglgN

15、MCCK1)()(NYHYY最高酸度时酸度即对应足够小最大应使为使)()()(NYHYHYMYKnMKspOH最佳酸度时的酸度对应曲线查spttpMpMpHpMMYNYMYNYKKKK甚至前提：3.141.25FeYK69.8lgMgYK已知63.4lg6)(HYpH2663.469.8lgMgKMgY无法准确滴定7.969.08lglg小）（应满足pHKMgYHY适用（判别式，6)lg%1.0%2.0MYSPMKCTEpM8202.0lg6lgPbYK04.10804.18lglglg)(PbYPbYHYKK2.32.3pHpH最高酸度查表，得50.16lg69.8lgZnYMgYKK，已知

16、45.0lg1045.6lg5）（）（，时时，HYHYpHpH)(lglglgHYMYMYKK根据可以准确滴定无法准确滴定：滴定824.845.069.8lg10824.245.669.8lg52MgYMgYKpHKpHMg可以准确滴定时：滴定805.1045.650.16lg52ZnYKpHZn适用（判别式，6)lg%1.0%2.0MYSPMKCTEpM8lg/01.0202.06lgFeYSPFeYFeYSPFeYKLmolCKC，）（由1.1781.25lglglg)(FeYFeYHYKK2.1pH最高酸度查表9.11324.3733310102103FeSPSPCKFeKOH水解酸度）

17、(1.29.1114pH1.22.1pH适宜酸度范围为/1000LmolVMmCZnOEDTA红色恰变蓝色标液滴加指示剂至碱性区，调缓冲溶液加）至微黄（滴加甲基红稀释加水溶样约加稀克基准物精称边滴边摇VmlEDTAEBTpHmlpHCLNHNHpHOHNHdmlmlHCLmZnO10)10(1.512534323红色恰变蓝色标液滴加指示剂至碱性区调缓冲溶液加微热溶样，放冷约加克精称葡萄糖酸钙样品VmlEDTAMgYEBTpHpHCLNHNHmlOHS)10(20432%10010004.448%1001000%SCVSMVCEDTAEDTA样葡萄糖酸钙葡萄糖酸钙黄色恰变橙色标液滴加指示剂缓冲溶

18、液加冷至室温分钟沸水浴稀释加水标液准确加入克精称明矾样品mlVZnSOdXOpHNaAcHAcmlmlVEDTAS2412)6(1025%1001000%44样明矾）（明矾SMVCVCZnSOZnSOEDTAEDTA%1001.4742211SVCVC）（黄色恰变橙色标液滴加指示剂冷至室温，补水分钟煮沸标液准确加入缓冲液加至析出白色沉淀滴加准确移取加水稀至滤液放冷，滤过加热溶样分别加盐酸和水各克精称氢氧化铝凝胶mlVZnSOmlXOmlVEDTAmlNaAcHAcOHNHmlmlmlS241231531025250,10%10010002502521322211SMVCVCOAL）（%1001

19、0002502521%324432样）（SMVCVCOALOALZnSOZnSOEDTAEDTA红色恰变蓝色标液滴加指示剂缓冲溶液加三乙醇胺准确量取水样水样VmlEDTAdEBTCLNHNHmlmlV35431000/1000/33水样水样）（）水的总硬度（）（）水的总硬度（VMCVLmgCaCOVMCVLCaOmgCaCOEDTACaOEDTA YHYYY1)(YHYYYY )(12345665626)(1aaaaaaaaaHYKKKKKKHKKHKHMMMMMMMM 1)()(AMLMM nnLMLLL221)(1 nnAMAAA221)(1YMYMYKKlglglgMMYMYKKlglg

20、lgYMMYMYKKlglglglg6lgMYspMKC2MspMCC注意：等浓度滴定时线）最高酸度（查酸效应曲)(lglglgMYMYHYKK）最低酸度（查SPMOHSPKMKOH)(MYSPMSPKCMlg(21MYSPMSPKpCpM无副反应）MKKpMpMHInMInMIntep(lglglg)(tpMpH下的或查表求出不同有副反应）（MpMpMpMMtteplg speppMpMpM先求出%1001010%spMMYpMpMCKTETTAAVCtaMm1000AAAMCT1000ATTAATMCtaVmTTAntanTTAAVCtaVC%1001000%SMVCtaAATTATVST AT%100%