中学化学阶段,遇到的等价代换主要有三种,它们分别是等质量代换、等电子代换和等价基代换.下面结合具体事例作简要介绍.1 等质量代换 等质量代换是已知式量求化学式时经常用到的解题方法.一般说来,如下关系成立 Ar(C)=Mr(12H); Ar(O)=Mr(CH4); Ar(N)=Mr(CH2) In the middle school chemistry stage, there are mainly three kinds of equivalent substitutions that are encountered. They are equal quality substitution, equal electronic substitution, and equivalent basis substitution. The following is a brief introduction with specific examples. 1 Quality and other quality substitution In other words, the problem solving method that is often used to find the chemical formula is known. In general, the following relationship holds: Ar(C)=Mr(12H); Ar(O)=Mr(CH4); Ar(N)=Mr (CH2)