University Chemistry ›› 2025, Vol. 40 ›› Issue (7): 315-320.doi: 10.12461/PKU.DXHX202408089

• Chemistry Laboratory • Previous Articles     Next Articles

Exploration of Abnormal Phenomena in Iodometric Copper Quantitation Experiment

Lancanghong Chen1, Xingtai Yu1, Tianlei Zhao2, Qizhi Yao1,3   

  1. 1 School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China;
    2 School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China;
    3 National Demonstration Center for Experimental Chemistry Education (University of Science and Technology of China), Hefei 230026, China
  • Received:2024-08-20 Accepted:2024-10-16 Published:2025-07-01
  • Contact: Qizhi Yao, Tianlei Zhao E-mail:qzyao@ustc.edu.cn;zhaotian@ustc.edu.cn

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Abstract: The iodometric determination of copper in alloys represents a fundamental experiment in analytical chemistry education. This study examines a notable case where a student erroneously used 20% KSCN solution instead of the prescribed HAc-NaAc buffer solution, yet surprisingly obtained CuSCN precipitate matching that of the standard procedure, albeit with significant discrepancies in titration results. Through systematic investigation of reaction intermediates and experimental validation, we elucidate the underlying chemical mechanisms responsible for this anomaly. This pedagogical approach not only enhances students' problem-solving capabilities but also demonstrates proper scientific investigation methodology for addressing unexpected experimental outcomes.

Key words: Iodometric method, Copper determination, Abnormal phenomena, Reaction mechanism