资料分析化学chap3

Titrimetric1.SomegeneralaspectsofTitrimetric1.Somegeneralaspectsof2.Classificationoftitrimetric3.PrimarystandardandStandard4.Volumetric1.Somegeneralaspectsof1-11.Somegeneralaspectsof1-1Titrimetry（TitrimetricanalysisTitrimetricmethods(volumetricmethods)includealargeandpowerfulgroupofquantitativeproceduresthatarebaseduponmeasuringtheamountofareagentofknownconcentrationthatisconsumedbytheanalyte.返–标准溶液中，直到所加的试剂与被测物质按化学–标准溶液中，直到所加的试剂与被测物质按化学1.Somegeneralaspectsof1-2Some(滴定准1.Somegeneralaspectsof1-2Some(滴定准确装在滴定管中的另一种溶液逐滴加入到被测溶液中的操作standardsolution（标准溶液）：(待测液待测定的物质1.Somegeneralaspectsofsp，化学计量点(Equivalence1.Somegeneralaspectsofsp，化学计量点(Equivalence point（ep，滴定终点（指示剂 error（Et，滴定误差1.Somegeneralaspectsofeg：HCl+Na21.Somegeneralaspectsofeg：HCl+Na2CO3=2NaCl+H2O+Indicator：甲基橙 **滴定分析通常用于测定常量组分，即被测组分的含量一般在1%以上。测定2.Classificationoftitrimetric2-1Requirementforthe2.Classificationoftitrimetric2-1Requirementforthechemicalquantitativereaction（>2.Classificationoftitrimetric2-2classification(chemicalreaction1Acid-base2Complex2.Classificationoftitrimetric2-2classification(chemicalreaction1Acid-base2Complex3Oxidation/Reduction4PrecipitationAg++ →Cr2O72-+6Fe2++14H→2Cr3++6Fe3+++Zn2++H2Y2-→ZnY2-+H++ →2.Classificationoftitrimetric2-3classification(Titration•Direct2.Classificationoftitrimetric2-3classification(Titration•Direct•Back•Replacement•Indirect2.ClassificationoftitrimetricBack•DeterminationofAl3+Al3++2.ClassificationoftitrimetricBack•DeterminationofAl3+Al3++EDTA（excess）Al3+-EDTA+standardsolutionEDTA（overplus）Zn2+-+standardsolutionC1V1-C2V2contentof2.Classificationoftitrimetric•Replacement2.Classificationoftitrimetric•Replacement在酸性条件下，硫代硫酸钠不能直接滴定重铬酸钾及其它氧化剂，因为这些氧化剂将S2O32-氧化成及SO4 Cr2O72-+6I-+ 2Cr3++3I2+I2+ 2I-+3.PrimarystandardandStandard3-13.PrimarystandardandStandard3-1somePrimaryahighlypurifiedcompoundthatservesasareferencematerialforatitrimetricmethodofanalysis.Standardsolution：asolutionwithknown3.PrimarystandardandStandard3-2PrimaryImportant因为摩尔相3.PrimarystandardandStandard3-2PrimaryImportant因为摩尔相同时，如果试差如M=300,M=ABA相对误差B相对误差molarmassQuantitativeAbsenceofhydrateStabilitytowardHigh3.PrimarystandardandStandard3.PrimarystandardandStandard标定标定还原剂：K2Cr2O7，标定AgNO3：acid-3.PrimarystandardandStandard级一二三中英标绿3.PrimarystandardandStandard级一二三中英标绿红蓝3.PrimarystandardandStandard3-3Standard3.PrimarystandardandStandard3-3Standard•3-3ADesirablepropertiesofstandardReact3.PrimarystandardandStandard3-3BMethodsforestablishingtheconcentrationofstandardsolutionPreparationof3.PrimarystandardandStandard3-3BMethodsforestablishingtheconcentrationofstandardsolutionPreparationofstandardmethod：准确称取一定量的基准物质，溶后配成一定体积的溶液，根据物质质量和溶液体积，可计算出该标准溶液的准确浓度(如Na2B4O710H2O ?1Lvolumetric3.PrimarystandardandStandardIndirectmethod(standardizedmethod)3.PrimarystandardandStandardIndirectmethod(standardizedmethod)：不能直接配制标准溶液的物质，可先粗略称取一定量物质（或量取一定体积溶液），配制成一种近似于所需浓度的溶液，然后再用基准物质或另一种物质的标准溶液来标定它的准确浓度（如HCl、NaOH、EDTAetc.）标定时注意：标定次数不少于3次，标定时的操作条3.PrimarystandardandStandard3-3CMethodsforexpressingtheconcentrationofstandardsolutionmol,物质的量nB3.PrimarystandardandStandard3-3CMethodsforexpressingtheconcentrationofstandardsolutionmol,物质的量nB摩尔质量MBM(B)gmol-cBc(B)molL-(mol.L1)nB(mol)nBcBVmBVn(mol)BMB3.PrimarystandardandStandardA/)TA/B3.PrimarystandardandStandardA/)TA/BA：被滴定的物质B例如用来测定Fe的K2Cr2O7标准溶液，其滴定=0.005000gmL-1TFe/指每mLK2Cr2O7恰好与0.005000g的Fe反应。如果在滴定中消耗 gmL-1×21.50mL=0.10753.PrimarystandardandStandardTA/BcB的关系aA+bB=cC+dannABbmaAcVBMbAamV1mLMcVAAB3.PrimarystandardandStandardTA/BcB的关系aA+bB=cC+dannABbmaAcVBMbAamV1mLMcVAABba3TMc()A/ABb4.Volumetric4-滴定剂B与被测物质A之间的计量aA+bB=4.Volumetric4-滴定剂B与被测物质A之间的计量aA+bB=cC+d注：多个反应式时确定计量关 a 溶 acBV AmA ac A b a 4.Volumetric–氟硅酸钾法测定SiO2时，先将SiO2处理成可溶性4.Volumetric–氟硅酸钾法测定SiO2时，先将SiO2处理成可溶性H2SiO3，在酸性介质中加入KF，过量KCl存在下，形成K2SiF6沉淀，沉淀在沸水中水解，生成HF，用NaOH标液滴定生成的HF，从而确定4.Volumetric H2SiO3 4.Volumetric H2SiO3 K23H2K2SiF63H2O4HFH2SiO HFNaOHNaFH~1molH2SiO~~21nSiO44.Volumetric4-2、ContentofanalyteaA+bB=cC+d acV AAA4.Volumetric4-2、ContentofanalyteaA+bB=cC+d acV AAA AbAmsWeightacV A100Weight或：ATAeg. WhatisthemolarityofK+inanaqueoussolutionthatcontains63.3ppmofK3Fe(CN)eg. WhatisthemolarityofK+inanaqueoussolutionthatcontains63.3ppmofK3Fe(CN)6(329.2g/mol)?31.005.77104mol/cKeg.Calculatethemolareg.CalculatethemolarconcentrationofHNO3(63.0g/mol)inasolutionthathasaspecificgravityof1.42andis70%HNO3(w/w).g 1.42greagent103mL70g3100gLmLg 1.42greagent103mL70g3100gLmL994gLL1mol994gcL15.863.0g3eg. TostandardizetheHClsolution,aprimarystandardNa2B4O710H2Oeg. TostandardizetheHClsolution,aprimarystandardNa2B4O710H2Owasdissolvedand21.20mLHClsolutionwasrequiredtothestoichiometricpoint.CalculatethemolarityoftheHClsolution.Na2B4O72HCl5H2O4H32nNaBO10H BO10Hc 2MNaBO10HO 220.1165mol381.3721.20eg.Themolarityoftheeg.Themolarityofthesolutionis0.01667mol.L-，（1）Fe/K2Cr2O7,TFe2O3/K2Cr2O7,TFe3O4/（2）a0.4500gsampleofironore,V(K2Cr2O731.62mL,calculatethepercentFe2O3 intheore。解6Fe2Cr2O14Hn2CrO72解6Fe2Cr2O14Hn2CrO726n61O=2 3211O=Cr n=(a/b)cBMVTA/K KTwAmsM(Fe)=55.85,M(Fe2O3)=159.7,M(Fe3O4)=M(Fe)=55.85,M(Fe2O3)=159.7,M(Fe3O4)=Cr MFe30.01667T Fe2O3/KTFeO/KCrO Cr K wFem s0.00798631.62100%eg. 基准物eg. 基准物质标定0.020mol.L-1的Na2S2O30.1(V=25 Na2S2O3 K解1mMK6K1(CV6MEr解1mMK6K1(CV6MErK0.1，须称取10倍量的基准物质，即0.25g2501(0.02025) 0.025(eg. 称取铁矿石试样0.5000g，将其溶解，使全部铁还原0eg. 称取铁矿石试样0.5000g，将其溶解，使全部铁还原0501点时，用去2Cr27标准溶液23.45mL，求试样中Fe和3–6Fe2+ = n6n61O=2 nFe31=Cr 6nKCr6cKCrVnFeFeKCrFe mmm6nKCr6cKCrVnFeFeKCrFe mmmsss60.0150023.4510355.85MFeMFenFeOCrOw mmss30.0150023.45