弱酸弱碱非线性回归电位返滴定的研究

DETERMINATION OF WEAK ACIDS AND WEAK BASES BY BACK TITRATION POTENTIOMETRY AND NOLINEAR REGRESSION

本文提出的方法是在被测弱酸或弱碱溶液中加入一定量过量ＮａＯＨ或ＨＣｌ标准溶液，再返滴入ＨＣｌ或ＨａＯＨ标准溶液若干次（５次左右），依次用电位法测定被测溶液中质子浓度，根据有关酸碱平衡和物料平衡原理及非线性回归原理对实验数据进行处理。本文探讨了有关误差问题、加权和选择滴定点问题。用模拟数据及实验数据验证表明，本方法能够准确测定包括ＮａＡｃ和（ＮＨ＿４）＿２ＳＯ＿４在内的弱酸弱碱。

The method proposed in the paper is as follows.A given amount of standard solution ofhydrochloric acid or sodium hydroxide is added in excess to the soultion of a weak base or a weakacid to be determined.Then the standard solution of xodium hydroxide or hydrochloric acid isadded in turn(five times or so)to the solution.After every addition of the standard solution theconcentration of the proton in the solution is measured by potentimetry,the experimental datebeing processed in terms of related acid-base equilibrium and material balances,and nonlinearregression. Weight faetors and titration points are determined. It is showed through thecomputation of simulated and experimental data that weak acids and weak bases such as NaAc and(NH_4)_ 2SO_4 can be accurately determined with the method.