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初中化学第140页74图“在圆铁片上放有铅、锡、锡和铅的合金小块加热使它们熔化来比较它们的熔点”一项实验,在课堂演示时全体学生不能明显看出。为了克服上述缺点改进教学起见。我先取锡、铅及软蜡各一粒,放在铁片上加热至熔,然后在它们开始冷凝时各插入一段细铜丝(长约4公分),铜丝上端再糊上不同颜色的小纸旗;这样放到铁片上加热。合金先熔,它上面的小旗先倒,全班学生都可以明显看出。实验的直观效果得以提高。
Junior High School Chemistry Page 140 of 74 Fig. “An experiment where small pieces of alloyed lead, tin, tin and lead were heated to melt them to compare their melting points” was not obvious to all students during the class presentation. In order to overcome the above shortcomings improve teaching. I first take tin, lead and soft wax one each and place them on an iron piece and heat it to melt. Then when they start to condense, insert a piece of fine copper wire (about 4 cm long), then paste the small pieces of paper of different colors Flag; so heated on iron. The alloy melts first, and the flag above it first falls, the whole class of students can clearly see. The visual effect of the experiment is improved.