极值─数轴─范围─混合物运算燕传永（山东枣庄８中２７７０００）范围讨论题是不少学生感到困难的计算题，在教学中用了找“极值”和数轴的方法，建立一定的思路可收到相应的效果，如：例１在标准状况下，Ｈ２和Ｃｌ２的混合气体Ｖ升，经光照后完全反应，所得气体恰好能... Extremum-number axis-range-mixture calculation Yan Chuanyong (8, 277,000, Zaozhuang, Shandong, China) The scope of the topic is that many students find it difficult to calculate problems. In teaching, they use the method of finding “extreme values” and number axes to establish a certain degree. The idea can receive corresponding results, such as: Example 1 In the standard condition, the mixed gas of H2 and Cl2 is liter. After reacting completely by light, the resulting gas just happens to be...