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一、理解质量守恒定律1．反应前后相等的是“质量”,而不是体积或分子总数等．2．必须是“参加反应”的各物质的“质量总和”与“反应生成”的各物质的“质量总和”相等,没有参加反应的物质不能算,参加反应的物质不能漏掉．3．所有的化学反应都遵循质量守恒定律．4．质量守恒定律可从微观和宏观两个角度去理解．从微观角度讲是因为“原子三不变”,即在化学变化前后,原子的种类没有改变,原子的数目没有增减,原子的质量
First, understand the law of conservation of mass. Equal before and after the reaction is the “quality”, not the volume or the total number of molecules. 2. The “sum of mass” of each substance that must participate in “reaction” is equal to the “sum of mass” of each substance produced by “reaction”. Substances that do not participate in the reaction cannot be counted, and substances participating in the reaction cannot be omitted. 3. All chemical reactions follow the law of conservation of mass. 4. The law of conservation of mass can be understood from both microscopic and macroscopic perspectives. From the microscopic point of view, it is because “the three atoms are invariable”, that is, before and after the chemical change, the type of the atom does not change, the number of atoms does not increase or decrease, and the quality of the atom