中学化学教学中挑选典型的例题,通过“一题多解、一题多变、多题一解”等手段加以分析解答,既能加强学生对知识的理解、方法的掌握,又能激发学生学习积极性,培养、提高学生思维能力。一、一题多解例1 200℃时11.6gCO_2和H_2O的混合气体与足量的Na_2O_2充分反应后,固体质量增加了3.6g,則原混合气体的平均分子量为( ) Select typical examples of chemistry teaching in middle school, through the “one problem and many solutions, one question changeable, many questions and answers” and other means to analyze and answer, not only can enhance students understanding of knowledge, methods, but also stimulate students to learn Enthusiasm, training, improve students thinking ability. First, a problem a lot of solutions 1 200 ℃, 11.6gCO 2 and H 2 O gas mixture with a sufficient amount of Na 2 O 2 fully reacted, the solid mass increased 3.6g, the original mixed gas average molecular weight ()