三、配位平衡常数M+Y=MY[MY ]KMY[M J[Y ][M:[Y]K不稳K[MY ]稳KMY一配合物的稳定常数（或形成常数）K不稳一配合物的不稳定常数（或离解常数）
三、配位平衡常数 M + Y = MY M Y MY K MY KMY — 配合物的稳定常数（或形成常数） K不稳 — 配合物的不稳定常数（或离解常数） 稳 不稳 MY K M Y K 1 [ ] [ ] [ ]
配合物的逐级稳定常数K[ML]（不稳，=六KM+LMLK[M][L][ML2]KK:不稳n-lML + LML2K[ML][L]?[MLKMLn-1 + LMLK不稳K[ML n-1][L][ML] = ?[ML2] = ?[MLn] = ?
配合物的逐级稳定常数 Ki K = 1 [ML] [M][L] n K = K 1 1 M + L M L 不 稳 K = 2 2 [ML ] [ML][L] 1 2 1 n K ML + L ML2 不 稳 K = n n n K -1 [ML ] [ML ][L] ● ● ● 1 1 n K 不 稳 K ● ● ● ● ● ● MLn-1 + L MLn [ML] = ？ [ML2 ] = ？ [MLn ] = ?
逐级稳定常数K累积稳定常数β[ML][ML]KrM+L=MLβ=K;=[MI[L][M][L][ML2][ML2]ML + L= ML2β-KK2K-[MLIL][M][L]?.Q.:[ML,][ML,]MLn-1 + L= ML,K.β-KK, .K.[MLn-][L][M][L]"[ML] = β, [M] [L][ML2]= β2 [M] [L]2[MLn ]= β, [M] [L]
逐级稳定常数 Ki ● ● ● ● ● ● ● ● ● M + L = ML ML + L = ML2 MLn-1 + L = MLn 累积稳定常数 [ML] [M][L] K1= [ML2] [ML][L] K2= [MLn ] [MLn-1][L] Kn = [ML] [M][L] 1=K1= [ML2] [M][L] 2 2=K1K2= [MLn ] [M][L]n n =K1K2 ···Kn = [ML] = 1 [M] [L] [ML2] = 2 [M] [L] 2 [MLn ]= n [M] [L]n
酸可看成质子配合物A= 1010.26β =K,= 1010.26KFY4- +H+ =HY3-Ka61HY3- +H+ = H,Y2-β2=K,K,= 1016.42= 106.16K,= Ka51H,Y2- +H+ = H,Y= 102.67β 3-K,K,Ks= 1019.09Ks=Ka41H,Y- + H+ = HYβ 4=K,K,K,K= 1021.09= 102.00K= Ka31HY +H+ = HY+β s=K,K2..Ks= 1022.69= 101.60Ks=Ka2H,Y++H + = H,Y2+1β=K,K2..K = 1023.59= 10 0.90K=Ka1[HY] = β, [H] [Y][H,YI =B2 [H]2[Y]
酸可看成质子配合物 Y4- + H+ ＝ HY3- HY3- + H+ ＝ H2Y2- H2Y2- + H+＝ H3Y- H3Y- + H+＝ H4Y H4Y + H+＝ H5Y+ H5Y+ + H +＝ H6Y2+ K1= = 1010.26 1=K1= 1010.26 1 Ka6 K2= = 106.16 2=K1K2= 1016.42 1 Ka5 K3= = 102.67 3=K1K2K3= 1019.09 1 Ka4 K4= = 102.00 4=K1K2K3K4= 1021.09 1 Ka3 K5= = 10 1.60 5=K1K2 .K5= 10 22.69 1 Ka2 K6= = 10 0.90 6=K1K2 .K6 = 1023.59 1 Ka1 [HY] = 1 [H] [Y] [H2Y] = 2 [H] 2 [Y]
S5-3 外界条件对EDTA与金属离子配合物稳定性的影响MY+MY（主反应）一OH-H+OHYHYNYMLMOHMHYMOHY副反应H,YM(OH)nMLn酸效干扰离辅助配羟基配混合配位效应位效应应子效应位效应M'Y(MY)
§5-3 外界条件对EDTA与金属 离子配合物稳定性的影响 M + Y = MY(主反应) MOH ML HY NY MHY MOHY 羟基配 位效应 M(OH)n MLn H6Y 辅助配 位效应 酸效 应 干扰离 子效应 混合配位效应 M Y (MY) OH- L H+ ● ● ● ● ● ● N H+ OH- 副 反 应 ● ● ●