弱电解质解离热力学研究 Ⅰ.对硝基苯酚-NaCl-水体系

Thermodynamics of Ionization of Weak Electrolyte Ⅰ.The System of p-Nitrophenol—NaCl—Water

本文在298.15±0.2K 测定了九个恒定离子强度不同 pH 值缓冲溶液中对硝基苯酚有等吸收点的紫外谱图.在恒定总离子强度为 I=0.1-2.0mol/kg 条件下,利用谱图中的光密度数据和测定的 pH 值,根据扩展的 Debye-Hückel 公式外推得到 pK°=7.246.K°为对硝基苯酚的热力学解离常数.本文又提出了用多项式拟合法确定 pK°,其值为7.308.两者在实验误差范围内一致.

The thermodynamic ionization constant K° of p-nitrophenol is derived frommeasurements of absorption spectrum and of pH by two methods Debye-Hückelextrapolation and polynomial approximation proposed by us in suitable phosphatebuffer solutions at constant ionic strength from 0.1—2.0 mol/kg at 298.15±0.1 K.Theresults from the both methods are pK°=7.246 and 7.308,respectively,which are ingood agreement within experimental error.