论文部分内容阅读
磷酸是中强酸,氨水是弱碱,二者组成的盐——磷酸铵的水溶液,有些书本认为是显酸性的,我认为是不对的。因为,他只注意了磷酸是一种中强酸的一面,而忽视了它是三元酸的一面。磷酸根离子也能够水解,而它的水解又主要取决于第一级水解。那么,(NH_4)_3PO_4在水溶液中发生的反应为NH_4~++PO_4~(3-)+H_2O(?)NH_3·H_2O+HPO_4~(2-)。水解得到的是弱碱NH_3·H_2O和弱酸HPO_4~(2-),而不是NH_3·H_2O和H_3PO_4.
Phosphoric acid is a medium-strong acid. Ammonia is a weak base. The salt, an aqueous solution of ammonium phosphate, is considered by some books to be acidic. I think it is wrong. Because he only paid attention to the fact that phosphoric acid is a medium-strong acid, and ignored the fact that it is a tri-acid. Phosphate ions can also be hydrolyzed, and its hydrolysis is mainly dependent on the first stage of hydrolysis. The reaction of (NH_4)_3PO_4 in aqueous solution is NH_4~++PO_4~(3-)+H_2O(?)NH_3·H_2O+HPO_4~(2-). Hydrolysis yields weak base NH 3 H 2 O and weak acid HPO 4 2 instead of NH 3 H 2 O and H 3 PO 4 .