大学化学 >> 2019, Vol. 34 >> Issue (2): 49-54.doi: 10.3866/PKU.DXHX201806014

化学实验 上一篇    下一篇

三氯化六氨合钴(Ⅲ)实验式确定实验的改进研究——电位滴定法测定氯含量

王周,石建新*(),彭敏,郑赛利,李莲云,赖瑢,朱可佳   

  • 收稿日期:2018-06-15 发布日期:2019-02-26
  • 通讯作者: 石建新 E-mail:cessjx@mail.sysu.edu.cn
  • 基金资助:
    2017年中山大学校级质量工程项目“重点教材建设项目”

Improving Experiment on Determining the Empirical Formula of Hexamine Cobalt(Ⅲ) Chloride: Measuring the Chlorine Content by Potentiometric Titration

Zhou WANG,Jianxin SHI*(),Min PENG,Saili ZHENG,Lianyun LI,Rong LAI,Kejia ZHU   

  • Received:2018-06-15 Published:2019-02-26
  • Contact: Jianxin SHI E-mail:cessjx@mail.sysu.edu.cn
  • Supported by:
    2017年中山大学校级质量工程项目“重点教材建设项目”

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摘要：

“三氯化六氨合钴（Ⅲ）的制备及其实验式的确定”是基础化学实验中的一个综合实验。该实验以活性炭为催化剂，CoCl2与氧化剂H2O2、过量氨水、NH4Cl反应制备三氯化六氨合钴（Ⅲ），通过测定产物中的氨、钴、氯含量，求出整数比，从而来确定其实验式。本文对氯的测定方法进行了改进研究，比较了电位滴定法和莫尔法测定产物中氯含量的效果。实验证明电位滴定法精密度高、重现性好、结果更可靠、教学效果更好。

关键词: [Co(NH3)6]Cl3, 实验式, 莫尔法, 电位滴定法

Abstract:

The experiment on preparation and empirical formula determination of hexamine cobalt(Ⅲ) chloride is a comprehensive experiment in the basic chemistry laboratory. The coordination compound was prepared by the reaction of CoCl2 with H2O2 as the oxidant, excess ammonia and NH4Cl with the catalysis of activated carbon. The empirical formula of the product was obtained by taking the integer of the ratio of NH3, Co and Cl based on their contents from titration. In this paper, the titration method of Cl was improved. The Cl contents from the potentiometric titration method and Mohr method were compared. Results show that the potentiometric titration method has the advantages of higher precision, better reproducibility and reliability, as well as the better teaching effect.

Key words: [Co(NH3)6]Cl3, Empirical formula, Mohr method, Potentiometric titration method