University Chemistry ›› 2018, Vol. 33 ›› Issue (8): 52-57.doi: 10.3866/PKU.DXHX201802013

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Criterion for Accurate Stepwise Titration of Mixed Acids

Xuanfeng YUE1,Yue ZHANG1,Yanni ZHANG2,Honglan QI1,Chengxiao ZHANG1,*()   

  1. 1 Key Laboratory of Analytical Chemistry for Life Science of Shaanxi Province, Shaanxi Normal University, Xi'an 710062, P. R. China
    2 Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, Shaanxi Normal University, Xi'an 710062, P. R. China
  • Received:2018-02-09 Published:2018-08-30
  • Contact: Chengxiao ZHANG
  • Supported by:


A mixture of monobasic strong acid and monobasic weak acid was chosen to derive the universal criterion for evaluating the feasibility of accurate stepwise titration of equimolar mixture with indicators. It is found that with an acceptable maximum relative error of 0.1%, the accurate stepwise titration can't be achieved unless two requirements are satisfied:the concentration of each acid is no less than 0.544 mol·L-1, and the pKa of weak acid is in the range of 5.6-8.3. The requirements vary with the acceptable maximum relative error.

Key words: Mixed acid, Stepwise titration, Direct and accurate, Criterion