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碘酒五变色实验涉及新课程化学1、2(必修)中卤素、二氧化硫及氧化还原反应等重要内容。在教学中让学生通过对本实验的操作,不仅使学生感受到了化学世界的奥妙无穷,巩固和提升了对相关知识的理解,还较好地激发了学生学习化学的兴趣。一、实验原理火柴头里含有硫黄、氯酸钾等,划燃火柴头后会产生少量二氧化硫气体。在水溶液中,单质碘与生成的二氧化硫反应,生成无色的氢碘酸。氢碘酸遇双氧水后被氧化而又重新析出单质碘。单质碘遇淀粉会变蓝色。单质碘遇氢氧化钠溶液,会发生歧化反应而生成无色的物质。反应的化学方程式为:
The iodine five-color changing experiment involves important elements such as halogens, sulfur dioxide, and redox reactions in the new course chemistry 1,2 (required). In the teaching, students are allowed to pass the experiment to not only make students feel the wonders of the chemical world, but also to consolidate and enhance their understanding of related knowledge, and also to stimulate students’ interest in learning chemistry. First, the experimental principle Match head contains sulfur, potassium chlorate, etc., will cause a small amount of sulfur dioxide gas after the burning of the match head. In aqueous solution, elemental iodine reacts with the generated sulfur dioxide to produce colorless hydrogen iodide. Hydroiodic acid was oxidized in the presence of hydrogen peroxide and elemental iodine was re-precipitated. Starch iodine will turn blue in starch. When elemental iodine meets sodium hydroxide solution, a disproportionation reaction occurs and a colorless substance is produced. The chemical equation of the reaction is: