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人教版九年级化学上册第13页图1-12:点燃蜡烛刚熄灭时的白烟,观察蜡烛能否重新燃烧?笔者在教学过程中发现,按教材介绍方法(图1)点燃,实验较难成功。经探讨分析认为,蜡烛熄灭产生的白烟量少,扩散后无法达到实验要求。一、实验改进取50 mL烧杯,倒入融化的石蜡,在烧杯中间竖立一支粉笔,大头朝上,以粉笔高于蜡烛(自制蜡烛)1 cm为佳。点燃粉笔后,用石棉网中间的铁丝网从火焰的下部分切入正在燃烧的
Figure 1-12: When the candle just extinguished the white smoke, observe the candle can burn again? The author found in the teaching process, according to teaching methods (Figure 1) lit, the experimental Difficult to succeed. After the discussion and analysis, the amount of white smoke produced by the candle extinguishing is small, and the experimental requirements can not be achieved after the diffusion. First, the experimental improvements Take 50 mL beaker, pour the melted paraffin, erected a beaker in the middle of the beaker, bulk up, to chalk higher than the candle (homemade candle) 1 cm better. After lighting the chalk, cut the barbed wire in the middle of the asbestos net from the lower part of the flame into the burning