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浅析变化在初中阶段,物质的变化分为物理变化和化学变化。从宏观上看,判断物理变化和化学变化的根本依据是看变化前后是否有新物质生成,有新物质生成的变化是化学变化,无新物质生成的变化是物理变化。物质在发生化学变化的过程中一定会伴随物理变化,而物理变化的过程中一定没有化学变化。在化学变化中时常伴随一些现象如:有发光、放热、变色、产生气体或沉淀,它们可以帮助我们判断是否发生了化学变化。但是有了这些现象不能说明一定是化学变化,也不是所有的化学变化都会产生这些现象。我们要透过现象来看本质,即是否有新物质生成。从微观上看,由分子构成的物质在发生
Analysis of changes in the junior high school, the material changes are divided into physical and chemical changes. From a macro point of view, the fundamental basis for judging physical changes and chemical changes is to see whether new substances are generated before and after the change, that new chemical substances produce changes that are chemical changes, and that no new substances generate changes that are physical changes. Material in the chemical changes in the process must be accompanied by physical changes, and physical changes in the process must be no chemical changes. In chemical changes are often accompanied by some phenomena such as: there is light, heat, discoloration, gas or precipitate, they can help us determine whether the chemical changes occurred. But with these phenomena can not explain the chemical change, not all of the chemical changes will produce these phenomena. We want to see the essence through the phenomenon, that is, whether there is a new material generated. From the microscopic point of view, the matter of molecules is taking place