絡合平衡和絡合滴定法-文庫吧資料
2025-05-21 22:22本頁面
【正文】 1. 絡合滴定曲線 例 : 用 ] [M39。 [M?] ?M= [M] [Y?] ?Y= [Y] [MY?] ?MY= [MY] 1. 副反應系數(shù) M + Y = MY 主反應 副反應 OH L H+ N H+ OH MOH MHY MOHY NY HY M(OH)n ● ● ● ● ● ● ML MLn H6Y ● ● ● ● ● ● ● ● ● ● ● ● [M?] [Y?] [MY?] a. 絡合劑的副反應系數(shù) ?Y: ?Y(H)： 酸效應系數(shù) ?Y(N)： 共存離子效應系數(shù) [Y?] ?Y= [Y] H+ N NY HY H6Y ● ● ● ?Y M + Y = MY 1 ?Y 酸效應系數(shù) ?Y(H)： [Y?] ?Y(H)= = = [Y] =(1+?1[H+]+?2[H+]2+…+ ?6[H+]6) [Y] [Y]+[HY]+[H2Y]+…+[H 6Y] [Y] [Y]+[Y][H+]?1+[Y][H+]2?2+…+[Y][H +]6?6 = ?Y(H) ≥1 [Y?] ?Y(H) [Y] = lg? Y(H)～ pH圖 lg?Y(H) EDTA的酸效應系數(shù)曲線 共存離子效應系數(shù) ?Y(N) [Y?] ?Y(N)= = = 1+ KNY[N] [Y] [Y] [Y]+[NY] [Y?] ?Y(N)= = = 1+KN1Y[N1]+KN2Y[N2]+…+ KNnY[Nn] =?Y(N1)+?Y(N2)+…+ ?Y(Nn)(n1) [Y] [Y] [Y]+[N1Y]+[N2Y]+…+[N nY] 多種共存離子 Y的總副反應系數(shù) ?Y = ?Y(H) + ?Y(N) 1 ?Y= = [Y]+[HY]+[H2Y]+ EDTA H6Y2＋ ＝ H+ + H5Y+ H5Y＋ ＝ H+ + H4Y H4Y ＝ H+ + H3Y H3Y ＝ H+ + H2Y2 H2Y2 ＝ H+ + HY3 HY3 ＝ H+ + Y4 Ka1= = [H+][H5Y] [H6Y] Ka2= = [H+][H4Y] [H5Y] Ka3= = [H+][H3Y] [H4Y] Ka6= = [H+][Y] [HY] Ka5= = [H+][HY] [H2Y] Ka4= = [H+][H2Y] [H3Y] MEDTA螯合物的立體構型 OC aOONONCOH2C H 2CC H2C H2CCC H2CH2COOOEDTA 通常與金屬離子形成 1:1的螯合物 多個 五元環(huán) 某些金屬離子與 EDTA的形成常數(shù) Hg2+ Th4+ Fe3+ Bi3+ Fe2+ Al3+ Zn2+ Cd2+ Pb2+ Cu2+ Mg2+ Ca2+ Na+ lgK lgK lgK lgK 1. 絡合物的穩(wěn)定常數(shù) (K, ? ) M + Y = MY 絡合平衡常數(shù) [MY] [M][Y] KMY= 逐級穩(wěn)定常數(shù) Ki ● ● ● ● ● ● ● ● ● K 表示 相鄰 絡合物之間的關系 M + L = ML ML + L = ML2 MLn1 + L = ML
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