论文部分内容阅读
例题 下列变化中,一定属于化学变化的是( )。 (A)变色 (B)爆炸 (C)发热 (D)自燃 分析:通过化学学习,同学们知道变色有两类:一类是变色无新物质生成,属物理变化(如无色氧气在-183℃时,变成淡蓝色液体,铁熔化变成红铁水);另一类是变化进程中有新物质生成,属化学变化(CuSO_4遇水生成CuSO_3·5H_2O,由白色变成蓝色,铜绿受热分解生成黑色固体)。 爆炸也有两类:一类是无新物质生成的爆
Example of the following changes, it must be chemical changes (). (A) Discoloration (B) Explosion (C) Fever (D) Spontaneous combustion analysis: Through chemistry learning, students know that there are two types of discoloration: one is discoloration and no new substance is generated, which is a physical change (such as colorless oxygen at -183 At °C, it turns into a light blue liquid, and iron melts into red iron water); the other is the formation of new substances in the course of the change, which is a chemical change (CuSO_4 forms CuSO_3·5H_2O in water, changes from white to blue, patina Thermal decomposition produces black solids). There are also two types of explosions: one is the explosion without new substances.