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讲镁铝性质时，为了向学生说明镁铝都为较活泼的金属，都能将铜盐溶液中的Cu2+置换出来，教师往往给学生演示镁和CuSO4溶液的置换反应实验．但因CuSO4溶液呈酸性，操作中常见镁片放入后不是在镁片上析出光亮的铜，而是看到有大量气泡产生，同时析出大量黑色粉末．由于此时学生
When talking about the nature of magnesium and aluminum, in order to explain to students that magnesium and aluminum are all more active metals, Cu2+ in the copper salt solution can be replaced. Teachers often show students the displacement reaction experiments of magnesium and CuSO4 solutions. However, due to the acidity of CuSO4 solution, the common magnesium tablets do not precipitate bright copper on magnesium tablets after operation. Instead, they see a large amount of bubbles and a large amount of black powders. Because of students at this time