University Chemistry ›› 2021, Vol. 36 ›› Issue (6): 2008008.doi: 10.3866/PKU.DXHX202008008

• Between Teacher and Student • Previous Articles     Next Articles

Mathematical Interpretation of Initial Curve of Acid-Base Titration between Strong Base and Weak Acid: Taking NaOH and HAc as an Example

Shuzhe Sun1,2, Zehao Zhang2,3, Bin Zhang1,*()   

  1. 1 School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
    2 Taishan College, Shandong University, Jinan 250100, China
    3 School of Life Sciences, Shandong University, Qingdao 266237, Shandong Province, China
  • Received:2020-08-03 Accepted:2020-08-11 Published:2020-09-10
  • Contact: Bin Zhang E-mail:binzhang68@sdu.edu.cn

Abstract:

In the acid-base titration curve of titration from NaOH to HAc, shown in the sixth edition of Analytical Chemistry edited by Wuhan University, we found that there was an obvious protruding part of the curve at the initial stage of titration, which was significantly different from the curve of titration from NaOH to HCl at the same concentration. In this paper, the mathematical expression of fitting the curve is derived by using various equilibrium relations in acid-base reaction. The correlation law of acid-base titration is proved by combining with the image of mathematical function. The mathematical model can explain not only the differences between two curves, but also the reasons and influencing factors of the initial titration curve difference of weak acids by strong alkali titration.

Key words: Analytical chemistry, Acid-base titration, Titration curves, Acid-base equilibrium, Mathematical model

MSC2000: 

  • G64