论文部分内容阅读
多年来用萘做晶体的熔解和凝固实验,效果并不明显,很难看到萘在熔解或凝固过程中温度保持在80℃不变。因而,难以以此为依据给学生建立起熔点、凝固点、熔解热等概念;难以比较晶体和非晶体的区别。另一方面,萘在常温下就具有强烈的刺激性臭味,加热熔解时更是臭气难忍。而且萘还是有毒物质,高浓度时损害肝肾,伤害视神经;诱发自内瘴,致人以溶血性贫血等。污染环境,受害者不限于做实验的师生。用过试管,很难洗净,只好报废。
For many years, using naphthalene as a crystal melting and solidification experiment, the effect is not obvious, and it is difficult to see that the temperature of naphthalene remains constant at 80° C. during melting or solidification. Therefore, it is difficult to establish a melting point, freezing point, heat of fusion and other concepts for students based on this; it is difficult to compare the difference between crystal and non-crystal. On the other hand, naphthalene has a strong irritating odor at room temperature, and it is unpleasant when heated and melted. Furthermore, naphthalene is still a toxic substance, which damages the liver and kidneys at high concentrations and damages the optic nerve; it induces internal hemorrhoids and causes hemolytic anemia. Contamination of the environment, the victims are not limited to the teachers and students doing experiments. Used test tubes, it is difficult to wash, had to be scrapped.