归东觅子大军 Analytical chemistry Chapter 7 precipitation titration The formation of a precipitate can be used as the basis of titration,provided that there is a suitable way of determining when a stoichiometric amount of titrant has been added.In this section we briefly introduce argenometry,a type of the precipitation titrations. 2025/4/3
Analytical chemistry 2025/4/3 Chapter 7 precipitation titration The formation of a precipitate can be used as the basis of titration, provided that there is a suitable way of determining when a stoichiometric amount of titrant has been added. In this section we briefly introduce argenometry, a type of the precipitation titrations
山东理子大写 Analytical chemistry 7.1 precipitation reactions The titrations of chloride,bromide,iodide,and other anions with silver (I are based on the formation of insoluble silver salts, such as: Ag+CI→AgCI↓ Ag+SCN→AgSCN↓ These procedures are termed argenometry
Analytical chemistry 7.1 precipitation reactions These procedures are termed argenometry. + → + → + + Ag SCN AgSCN Ag Cl AgCl - - The titrations of chloride, bromide, iodide, and other anions with silver (Ⅰ) are based on the formation of insoluble silver salts, such as:
G山东理王大子 Analytical chemistry Take the formation of AgCl procipitate as an example,its sulubility produce constant is Kp=ang da =[Ag']CI lYAgYa The solubility of AgCl precipitate is very small,and y are all approximate to 1,so K'sp =[Ag'][CI-] For the insoluble salt AB,if we take the side reactions into account,then 2025/4/3
Analytical chemistry 2025/4/3 Take the formation of AgCl procipitate as an example, its sulubility produce constant is + − + − + − = = A g Cl A g Cl s p K a a [Ag ][Cl ] The solubility of AgCl precipitate is very small, and γ are all approximate to 1, so [Ag ][Cl ] sp + − K = For the insoluble salt AB, if we take the side reactions into account, then
归东我子大军 Analytical chemistry [A'] [B'] 二0B [A] [B] Where a is the side reactions coefficient,so the conditional solubility product is introduced: Kp'=[A'][B'] 2025/4/3
Analytical chemistry 2025/4/3 A B [B] [B'] , [A] [A'] = α = α Where α is the side reactions coefficient, so the conditional solubility product is introduced: ' [A'][B'] Ks p =
归东龙卫大写 Analytical chemistry 7.2 Titration curves Consider the titration of 0.1 mol/L KCI with 0.1 mol/L AgNO3 solution.A titration curve can be prepared by plotting pCl ys the volume of AgNO3. At the beginning of the titration,pCl=1 As the titration continues,part of Cl is removed from solution by precipitation as AgCl,and the pCl is determined by the concentration of the remaining Cl;the contribution of Cl from dissociation of the precipitate is negligible,except near the equivalence point. 2025/4/3
Analytical chemistry 2025/4/3 7.2 Titration curves Consider the titration of 0.1 mol/L KCl with 0.1 mol/L AgNO3 solution. A titration curve can be prepared by plotting pCl vs the volume of AgNO3 . At the beginning of the titration, pCl=1 As the titration continues, part of Clis removed from solution by precipitation as AgCl, and the pCl is determined by the concentration of the remaining Cl- ; the contribution of Clfrom dissociation of the precipitate is negligible, except near the equivalence point