分析化学第四章酸碱滴定法课件.ppt

1、酸碱质子HACAc-+H+H2CO3HCO3-+H+HCO3-CO32-+H+NH4+NH3+H+H6Y2+H5Y+H+NH3OH+NH2OH+H+(CH2)6N4H+(CH2)6N4+H+NH4+H2O H3O+NH3 KKHOHsw101014.pHpOH 14KSHSs2水的离子积水的离子积KH OAHAa3KOHHAAbKKKabwKKKabsKKKaaa123321bbbKKK14132231100.1WbababaKKKKKKK CHAAHAaaHACHAHAAAHAKHHHK1111AaaACAHAAKHKHAA136.0100.11078.1100.1555HKHaHAc64.

2、036.01AcLmolCHAcHAc/036.036.01000.0LmolCAcAc/064.064.01000.0H2C2O4 HC2O4-+H+HC2O4-C2O42-+H+CH C OHC OC O224242421241211224HC OaaaaHC OCKHHKHKK2242122112242C OaaaaaC OCKKHKHKKCOCHOCH422422HHKHKKaaa221120121H3PO4 H2PO4-+H+H2PO4-HPO42-+H+HPO42-PO43-+H+233-3-OHCOHAHaaCHHKCHwaB+H+BH+H2O H+OH OHBHHOHKCOHW

3、bbCOHHAOHCKHaW1HCKHKKHaaaWHKKCKaaaa242HC KaaCKaa 500CKKaaW 20CKKaaW 20HCKHKaaaOHKKCKbbbb242OHC KbbHC Kaa11bbKCOH21aaKKH21aaKKHHKKaa23HCCKabaabaCCpKpHlgbaaCCpKpHlg或aHAKHHAHAHACHAaaAKHKAHAACAHAA1aCHbCOHaaKCHOHC KbbHC Kaa11bbKCOH21aaKKHHKKaa23HCCKabaabaCCpKpHlg酸式体 碱式体 或碱式体 酸式体 ee见插图(H3C)2+NNNHSO3OHH+(H

4、3C)2NSO3NHN甲基橙（MO）红色（醌式）黄色（偶氮式）pKa=3.4OHOHOHH+pKa=9.1HOCOOOOCOO羟式（无色）醌式（红色）酚酞（PP）KHInHInKinaKHInHInin HIn H+In-KHInHInin aCaHInInHKin KHOHKtw11101014.KAHA OHKKKtbaW1KHAHAKKKtabW1H3O+OH-H2O+H2OKHOHKtw11101014.）LmolCHa/1000.00.1pHLmolCVVVVHababa/100.51.098.1900.2098.1900.2053.4pHHOHKmolLw 107/0.7pHLmo

5、lCVVVVOHbbaba/100.51.002.2000.2000.2002.2053.4pOH7.9pH滴定开始，强酸缓冲区，滴定开始，强酸缓冲区，pH微小微小 随滴定进行随滴定进行，HCL ，pH渐渐 SP前后前后0.1%，pH ，酸酸碱碱 pH=5.4 继续滴继续滴NaOH，强碱缓冲区，强碱缓冲区，pHv甲基橙（3.14.4）*3.45v甲基红（4.46.2）*5.1v 酚酞（8.010.0）*9.1 1.0 mol/L NaOH1.0 mol/L HCL pH=3.310.7 选择甲基橙，甲基红，酚酞 0.1mol/Ll NaOH0.1mol/L HCL pH=4.39.7 选择甲基

6、红，酚酞，甲基橙（差）0.01mol/L NaOH0.01mol/L HCL pH=5.38.7 选择甲基红，酚酞（差）OH-+HA A-+H2OKAHA OHKKKtbaW1反应完全程度不高LmolKCHaa/1034.11000.0108.13588.2pHHACACaabaCCpKCCpKpHlglgCmolLHAC20001998200019980100050105./CmolLAC1998200019980100050102./76.7 pH27.5pOH73.8 pH30.4pOH70.9 pHLmolCVVVVOHbabab/100.51000.000.2002.2000.200

7、2.205bawbbCKKCKOHLmolCb/05000.021000.0滴定前，曲线起点高 滴定开始，Ac-，pH随滴加NaOH，缓冲能力，pH微小滴定近SP，HAc，缓冲能力，pHSP前后0.1%，酸度急剧变化，pH=7.769.7SP后，pH逐渐（同强碱滴强酸）Ka，酸性，pH Ka10-9时无法准确滴定 C ，pH，滴定准确性差H3O+A-HA +H2O KHAHAKKKtabW1反应完全程度不高pH=6.344.30选甲基橙，甲基红 H3PO4 H+H2PO4-H2PO4-H+HPO42-HPO42-H+PO43-66.42)(21aapKpKpH94.92)(32aapKpKpH

8、 溴甲酚绿溴甲酚绿+甲基橙甲基橙 酚酞酚酞+百里酚酞百里酚酞第一变色点 pH=4.66 选甲基橙，甲基红甲基橙，甲基红 溴甲酚绿溴甲酚绿+甲基橙甲基橙 第二变色点 pH=9.94 选酚酞，百里酚酞酚酞，百里酚酞 酚酞酚酞+百里酚酞百里酚酞CO32-+H+HCO3-Kb1=10-3.75HCO3-+H+H2CO3 Kb2=10-7.6237.82)(21aapKpKpH LmolKCHaa/103.104.0103.44719.3pH 第一变色点 pH=8.37 选酚酞酚酞 第二变色点 pH=3.9 选甲基红甲基红过程：NaOH HCL/NaCL HCL/-Na2CO3 V1 NaHCO3 V2

9、 H2O+CO2%1001000)(%21SMVVCNaOHNaOH%1001000221%32232SMVCCONaCONa过程：HCL/，V1 CO2+H2ONaOH+Na2CO3 NaOH+BaCO3 BaCL2 V2 HCL/NaCL+H2O%1001000%2SMCVNaOHNaOH%1001000)(21%322132SMVVCCONaCONa%1001000)(%SMVCVCNNNaOHNaOHHCLHCLaNH4+OH-NH3+H2O NH3 +HCL（定过量）NH4CL HCL(过量）+NaOH NaCL+H2O加热b%1001000%SMVCNNHCLHCL4NH4+6HC

10、HO (CH2)6N4H+3H+6H2O14NaOHNHnn%1001000%SMVCNNNaOHNaOH422)(424NHOHCONHCSOHSOCnmu解：aaCKH由0.3pH和510aK510bawbbCKKCKOH所以5pOH9pH解：2102100.1102.6100.1HKHaHCNHCNCN1CNHCN25.0lg3.5lgbabaCCCpKpH由加入前LmolCNaOH/05.0100401000200.0已知6.5050.025.005.0lg3.5bCpH由加入后LmolCb/35.045.520.035.0lg3.5pH原来的解：解：混碱 NaOH 酚酞 NaCL 甲基橙 -NaHCO3 V1 NaHCO3 V2 CO2 Na2CO3 NaHCO3 CO2%44.93%1002000C%HCLSMVHCL硼砂硼砂%11.34%B3232硼砂硼砂MMOOB%MMB%B硼砂硼砂