一、问题的提出三氧化硫在教学中占有重要地位,因为它是接触法制硫酸的重要中间产物,只有了解它的性质之后,才能更好地了解到制造过程中的有关问题。利用催化剂(Cr_2O_3)将SO_2氧化成SO_3的演示实验,我们过去早就制成过,用它演示SO_3在空气中发烟,溶解于水的过程发生酸雾和被浓硫酸吸收的情况等都很好。可是要确实叫学生看见在通常状况下,它是白色丝状晶体、与水激烈反应等,即需要固体的SO_3时,过去我组有的老师做过,但一直没有成功,同时认识上也有分歧。有人认为它没有多大意义,原因是二氧化硫本身的独立用途不大,只是制硫酸的中间产物,讲它是为硫酸的工业生产服务,何必非制出它不可呢?也有人认为别人 First, the issue put forward Sulfur trioxide in teaching occupies an important position, because it is an important intermediary contact with legal system sulfuric acid, and only understand its nature, in order to better understand the manufacturing process related issues. The use of catalyst (Cr_2O_3) to SO_2 oxidation SO_3 demo experiment, we have long been made in the past, with it demonstrated SO_3 in the air smoking, dissolved in water, the process of acid mist and concentrated sulfuric acid absorption are all very it is good. But to really tell the students to see under normal conditions, it is a white filamentous crystal, fierce reaction with water, etc., that need solid SO_3, the past, my group of teachers did, but has not been successful, at the same time, there are differences of understanding . Some people think that it does not make much sense because the independent use of sulfur dioxide is not large in itself. It is only an intermediate product of sulfuric acid. It is for sulfuric acid industrial production services, why not make it? Some people think that others