在中学化学课本的附录“酸、碱和盐的溶解性表(20℃)”中,在硫化铁处都打上“—”的符号,并在表下的说明中指出,“—”表示那种物质不存在或遇水就分解了。根据这一划“规戒”,在中学化学教学中,硫化铁被处以“死刑”。这样,人们就认为:在溶液中,铁盐与硫化物不能起直接的离子互换反应而生成硫化铁沉淀。 In the appendix “Table of Solubility of Acids, Alkali and Salts (20°C)” in the chemistry textbook for middle schools, the symbol “—” is added to the iron sulfide, and it is pointed out in the explanation in the table that “—” indicates that The substance does not exist or it decomposes with water. According to this “regulation,” iron sulfide was sentenced to death in chemistry teaching in middle schools. In this way, people think that: in solution, iron salts and sulfides can not play a direct ion exchange reaction to generate iron sulfide precipitation.