h******1
发帖数: 13 | 1 问个位化学专家一个问题.
meta-Phosphoric acid 是磷酸 (正磷酸, Phosphoric acid, also known as
orthophosphoric acid) 加热, 脱水, 聚合而成 (Upon heating orthophosphoric
acid, condensation of the phosphoric units can be induced by driving off the
water formed from condensation. When an average of one molecule of water
per phosphoric unit has been driven off, the resulting substance is a glassy
solid having an empirical formula of HPO3 and is called meta-phosphoric
acid). 按这个原理, meta-phosphoric acid 溶于水后, 它应该又变回磷酸. 对不对?
我有一个维生素C (Ascorbic acid) 的测定方法, 规定要用 3% 的meta-phosphoric
acid 水溶液来处理样品. Meta-phosphoric acid 比磷酸 贵许多. 如果meta-
phosphoric acid溶于水后, 又变回磷酸, 那为什么不直接用磷酸水溶液来处理样品?
为什么规定要用 3% 的metaphosphoric acid 水溶液?
多谢. | f******k
发帖数: 5329 | 2 不是所有吸热反应的逆反应都是自发的。换句话说，放热反应不一定是自发反应。 |
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