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在15°、25°、35°和45℃下测定间硝基苯甲酸在不同浓度的LiCl、NaCl、KCl、LiBr、NaBr、KBr、SrCl_2和BaCl_2的水溶液中的溶度。算出该酸的未离解分子在盐溶液中的活度系数γ_n它们在25℃下从盐溶液迁移到纯水溶液的克分子标准熵交化△S°。计算结果:△S°>0,△S°/m_s=常数,即△S°和盐浓度m_s成正比;△S°/m_s的次序是BaCl_2>SrCl_2>KBr>NaBr>KCl>LiBr>NaCl>LiCl,表明对具有同离子的盐,△S°/m_s随反电荷离子的价和晶体半径的增加而上升。用Frank和Evans的离子破坏水的结构来解释这些现象。从log f_u(f_u是体积克分子标度的该酸分子的活度系数)对C_s的图,得出盐析次序如下:SrCl_2>BaCl_2>LiCl>Nacl>LiBr>NaBr>KCl>KBr。用”局部水解”的假说解释这个次序。从log γ_u对t°的图发现KBr对该酸分子的盐析有一个转换温度,约为30℃;30℃以上是盐析,以下是盐溶。若用log f_u对t°的图,转换温度变为≈23℃。总结出一个该酸分子在纯水中的组成和绝对温度关系的经验公式;有效范围是15—45℃。最后算出该酸在四个温度的微分溶解热。
The solubility of m-nitrobenzoic acid in aqueous solutions of LiCl, NaCl, KCl, LiBr, NaBr, KBr, SrCl 2 and BaCl 2 at different concentrations was measured at 15 °, 25 °, 35 ° and 45 ° C. The activity coefficients of the undissociated molecules of the acid in the salt solution, γ_n, are calculated as the standard entropic cross-coupling ΔS ° of migration from the salt solution to the pure water solution at 25 ° C. The results show that ΔS °> 0, ΔS ° / m_s = constant, that is, ΔS ° is proportional to salt concentration m_s; order of ΔS ° / m_s is BaCl_2> SrCl_2> KBr> NaBr> KCl> LiBr> LiCl, indicating that ΔS ° / m_s increases with the valence of the counter-ion and crystal radius for salts with the same ion. These phenomena are explained by the structure of water destroyed by the ions of Frank and Evans. From log f_u (f_u is the activity coefficient of the acid molecule on the molecular gram scale) versus C_s, the salting-out order is obtained as follows: SrCl_2> BaCl_2> LiCl> Nacl> LiBr> NaBr> KCl> KBr. Use “local hydrolysis” hypothesis to explain this order. From the graph of log γ_u to t °, it is found that KBr has a transition temperature for salting-out of the acid molecule of about 30 ° C; salting-out is above 30 ° C and the following is salt-soluble. If you use log f_u t ° on the map, the conversion temperature becomes ≈ 23 ℃. Summarized an empirical formula of the acid molecule in pure water and absolute temperature relationship empirical formula; The effective range is 15-45 ℃. Finally, the differential heat of the acid at four temperatures is calculated.