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由于氧化剂的氧化性和还原剂的还原性都有差异,因此在书写氧化还原反应的离子方程式时就必然会涉及定性的问题;有时反应物的量又是变化的,这就涉及定量的问题。对这样的反应,在书写离子方程式时有一定的难度,学生往往难以完成。下面就氧化还原反应中定性与定量问题通过举例来说明其解答思路。一、涉及定性问题例1.将足量的锌粉投入到FeCl_3和CuCl_2混合溶液中,依次写出发生反应的离子方程式。分析:由于Fe~(3+)、Cu~(2+)、Fe~(2+)的氧化性依次减弱,因此,当
Due to the difference between the oxidizability of the oxidant and the reducibility of the reductant, a qualitative problem must be involved in writing the ion equation of the redox reaction; in some cases, the amount of the reactant changes again, which involves quantitative problems. For such reactions, there is a certain degree of difficulty in writing ion equations that students often find difficult to accomplish. Below on the redox reaction in the qualitative and quantitative issues by way of example to explain their ideas. First, the qualitative issues involved Example 1. The amount of zinc into the FeCl_3 and CuCl_2 mixed solution, followed by write the reaction ion equation. Analysis: Due to the weakened oxidation of Fe ~ (3 +), Cu ~ (2 +) and Fe ~ (2+)