用分光光度法测定弱电解质的解离常数——Ⅱ 溴酚蓝+氯化钠+乙醇+水体系

Determination of the Dissociation Constant of Bromophenol Blue in Pure Water and Mixed Solvents —II The System of Bromophenol Blue+EtOH+H_2O

本文用分光光度法,测定了在恒定不同离子强度下,混合溶剂中溴酚蓝的具有等级收点的吸收谱图。利用外推法和多项式拟合法,确定了溴酚蓝的热力学解离常数K^o,两种方法所得结果在实验误差范围内基本一致。本文还讨论了混合溶剂对溴酚蓝吸收谱图的影响。

The dissociation degrees of bromophenol blue at various total ionic strengths were measured in pure water and in 5,10 mass% ethanol-water mixed so solvents by U-3200 spectrophometer Their pH values of corresponding solution we were also measured by Orion EA 940 ionometer. The thermodynamic dissociation co constants of bromophenol blue in pure water and in the mixed solvents were determined by extrapolation and polynomial approximation. The effect of medium on a absorption spectra of bromophenol blue was discussed.