多重改良Logistic模型在磷酸电位滴定的离解平衡常数计算中的应用

基于磷酸电位滴定实验常用切线法、一阶微商法及二阶微商内插法等进行实验数据处理并计算磷酸离解平衡常数的烦琐与不准确性,提出一种与实验数据有高度吻合性的多重改良Logistic模型,应用优化求解得最佳函数表达式,解此函数一阶导数极大值点并计算得磷酸滴定半中和点,结合离解平衡常数校正公式最终得出了磷酸的离解平衡常数的各级pKa值,与文献结果相一致.另外,减少部分实验数据后应用模型处理并计算pKa值,所得结论仍具有一致性,从而提高了实验效率。

Application of Multiple Modified Logistic Model in Calculating Dissociation Constant of Potentiometric Titration of H3PO4

Because of the complexity and inaccuracy of processing the experimental data and calculating dis-sociation constant of H3PO4 in the experiment of Potentiometric titration by using tangent method,first time derivative method,second time derivative interpolation method etc,the multiple modified Logistic model which can match the experimental data better is set up.The optimal function expression is solved by optimization,and then the half neutralization point is calculated after the maxima points of the function of first derivative is found.Therefore,the pKa of dissociation constant of H3PO4 is finally gotten in virtue of the corrector formula of dis-sociation constant,which highly accords with the results of the reference paper.Moreover,the result of the pKa is still extremely consistent with the former one in the condition of reducing a part of the experimental data,thus the efficiency of the experiment is improved.