关于一元酸准确滴定判据的商榷

• 作 者: 王欢 李梦龙 周向葛
• 机 构: 四川大学化学学院,
• 出 处: 化学通报
• 发表日期: 2014年11期
• 关键词: 滴定 酸碱滴定 突跃范围 滴定突跃 准确滴定 浓度 一元酸 酸溶液 滴定剂 判据

化学分析教科书中给出的弱酸能被准确滴定的条件是cKa≥1.0×10-8。本文根据这一判据的来源(滴定突跃≥0.3pH单位),对一元酸体系的滴定情况进行了严格数学处理。计算结果表明,只有同时满足弱酸的浓度c>1.0×10-3mol/L和cKa≥1.0×10-8条件下,弱酸才能被准确滴定。对于浓度极稀的酸溶液(c≤1.4×10-4mol/L),无论强酸还是弱酸都不能被准确滴定。对教材很少涉及的不同浓度酸碱互相滴定的情况也给出了有价值的结论。

The conditions for the accurate titration of weak acids given in the textbook of chemical analysis are cKa ≧ 1.0 × 10-8. This article based on the source of this criterion (titration jump ≥ 0.3pH units), monobasic acid titration of a rigorous mathematical treatment. The calculated results show that the weak acid can be accurately titrated only when the concentrations of weak acids c> 1.0 × 10-3mol / L and cKa≥1.0 × 10-8 are satisfied simultaneously. For the extremely dilute acid solution (c ≤ 1.4 × 10-4mol / L), both strong and weak acids can not be accurately titrated. On the teaching material is rarely involved in different concentrations of acid-base titration with each other also gives valuable conclusions.