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一、从有目的、有选择的观察做起 要培养学生的思维能力,就要从有目的,有选择的观察实验现象做起。 例如,石蜡的催化裂化实验分催化裂化,部分裂化气冷凝,气态烃通入高锰酸钾溶液三个部分,观察的目的应放在石蜡(加有催化剂)熔化后,继续加热过程中,要求学生观察冷凝装置中出现雾状物及液滴,和插入高锰酸钾溶液的导管有多量气泡的逸出,并以此为主要现象和同学共同讨论,得出由固态烃石蜡经催化裂化得到液态烃和气态烃的总的概念。其次,再要求学生从生成的液体汽油气味及其分别与高锰酸钾溶液,溴水反应等现象的观察,分析生成的烃含不饱和烃成分。
First, start with purposeful and selective observations To cultivate students’ thinking ability, we must begin with the purposeful and selective observation experiment phenomenon. For example, the paraffin wax catalytic cracking experiment is divided into catalytic cracking, partial cracking gas condensation, gaseous hydrocarbons passed into three parts of potassium permanganate solution, the purpose of observation should be paraffin (plus catalyst) after melting, continue heating process, requirements The students observed the appearance of mists and droplets in the condensing device, and the escape of a large number of bubbles in the catheter inserted with the potassium permanganate solution, and this was the main phenomenon discussed with the classmates. The result was that the solid hydrocarbon wax was catalytically cracked. The general concept of liquid hydrocarbons and gaseous hydrocarbons. Secondly, students are asked to analyze the generated hydrocarbon-containing unsaturated hydrocarbon components by observing the phenomenon of liquid gasoline odor generated and its reaction with potassium permanganate solution and bromine water, respectively.