初三化学教材中验证质量守恒定律的两个实验，我认为操作不够简便，容易引起实验误差。尤其是白磷燃烧前后质量测定的实验在容器外点火不安全且会污染环境。对此，我进行了以下改进，效果很好且具有普遍推广应用的价值。１白磷燃烧前后质量测定实验ａ．实验材料。托盘天平（２ The two experiments in the third grade chemistry textbook to verify the law of conservation of mass, I think that the operation is not easy, it is easy to cause experimental error. Especially the experiment of mass measurement before and after burning of white phosphorus is not safe to ignite outside the container and can pollute the environment. In this regard, I have made the following improvements, which are very effective and have the value of universal promotion and application. 1 Mass spectrometry experiments before and after white phosphorus combustion a. Experimental Materials. Tray balance (2