题干

某兴趣小组话动中,同学们按图1装置对“可燃物燃烧的条件”进行探究.探究过程中,大家对磷燃烧生成的大量白烟是否危害人体健康提出疑问.①温度未达到红磷的着火点

②热水中的白磷没有与氧气(或空气)接触

[反思与评价](1)能防止白磷燃烧产生的五氧化二磷逸散,危害人体健康.(2)避免橡皮塞因试管内气体热膨胀而松动.(合理答案均可)[拓展与迁移]甲氧气约占空气体积的

1
5
.且上述实验白磷足量、气密性良好,所以进入a试管内液体的体积能接近试管容积的
1
5
(或乙装置漏气等)(其它合理答案均可)

白磷的着火点是40℃,红磷的着火点是240℃,…燃烧产物五氧化二磷是白色固体,会刺激人体呼吸道,可能与空气中水蒸气反应,生成有毒的偏磷酸(HPO3).

变流与讨论:白烟对人体健康有害,该实验装置必须改进.

改进与实验:同学们按改进后的图2装置进行实验.

上一题 下一题 0.0难度 选择题 更新时间:2017-11-17 03:19:17

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