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在初中化学学生分组实验八,安排有金属锌置换硫酸铜溶液中Cu~(2+)的实验。此实验的目的是让学生通过实验,掌握和巩固金属与盐之间相互反应的规律,以及进一步加深对金属活动顺序表知识的认识。但是,我们在做此实验时发现金属锌(不论是锌片、锌粒、纯锌或不纯锌)与硫酸铜溶液(不论浓度大小)直接作用,置换出的生成物,不是具有金属光泽的红色铜,而是一种附着在锌表面的黑色沉淀物。只有把锌在硫酸铜溶液中放置一小时以上,
In junior high school chemistry student grouping experiment 8, experiments were conducted to replace copper 2+ in copper sulfate solution with metallic zinc. The purpose of this experiment is to let students through experiments, grasp and consolidate the mutual reaction between metal and salt, and further deepen the knowledge of metal activity sequence table. However, when we did this experiment, we found that metal zinc (whether zinc, zinc, pure zinc or impure zinc) and copper sulfate solution (regardless of the concentration) play a direct role in the replacement of the product, not a metallic luster Red copper, but a black precipitate attached to the zinc surface. Only put zinc in the copper sulfate solution for more than one hour,