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磷酸是中学学到的唯一的一个中等强度的三元酸,有关磷酸及其对应的几种盐的性质,常常会结合在离子共存、物质鉴别与制取、溶液导电性、盐类水解、过量计算、实际生产及一些重要概念中进行考核。在平时的学习中,要注意防止在这些方面出现漏洞。一、磷酸(H_3PO_4)、偏磷酸(HPO_3)、焦磷酸(H_4P_2O_7)三者的关系,它们既不是同位素也不是同素异形体,而是由同一种酸酐——五氧化二磷与水在不同条件下发生反应所生成的产物,其中偏磷酸剧毒。
Phosphoric acid is the only medium-strength tribasic acid that is learned in middle school. The nature of phosphoric acid and its corresponding salts are often combined with ion coexistence, material identification and preparation, solution conductivity, salt hydrolysis, and excess. Calculations, actual production, and some important concepts are evaluated. In peacetime learning, care should be taken to prevent loopholes in these areas. 1. The relationship among phosphoric acid (H_3PO_4), metaphosphoric acid (HPO_3), and pyrophosphoric acid (H_4P_2O_7), which are neither isotopes nor allotropes, but are derived from the same acid anhydride, phosphorus pentoxide, and water. The product produced by the reaction under the conditions, among which the metaphosphoric acid is extremely toxic.