Azab H A
Chemistry Department, Faculty of Science, Assiut University, Assiut, Egypt.
Talanta. 1993 Jun;40(6):863-6. doi: 10.1016/0039-9140(93)80043-q.
The secondary dissociation constants of o-phthalic and phosphoric acids have been determined in methanol + water (50 mass %) from reversible e.m.f. measurements of the cell of the type: Pt, H(2)(1 atm)|M(2)A(m), MHA(m), MCl|AgCl; Ag at different temperatures (288.15-308.15 K) and at different ionic strengths. To minimize the unsteadiness in potential measurements palladium coated platinum electrodes have been used. The large set of such e.m.f. values has been analyzed in terms of a multi-linear regression method recommended in recent IUPAC documents. The thermodynamic values DeltaG degrees , DeltaH degrees and DeltaS degrees , for the respective equilibria, were estimated. Standard pH values [pH*(s)] have been assigned to buffers in methanol + water (50 mass %) at temperatures between 288.15 and 308.15 K.
通过对如下类型电池进行可逆电动势测量，在甲醇 + 水（50质量%）体系中测定了邻苯二甲酸和磷酸的二级解离常数：Pt, H₂(1 atm)|M₂Aₘ, MHAₘ, MCl|AgCl; Ag，测量温度范围为288.15 - 308.15 K，离子强度不同。为使电位测量的不稳定性降至最低，使用了镀钯铂电极。根据国际纯粹与应用化学联合会（IUPAC）近期文件推荐的多元线性回归方法，对大量此类电动势值进行了分析。估算了各平衡反应的热力学值ΔG°、ΔH°和ΔS°。在288.15至308.15 K的温度范围内，为甲醇 + 水（50质量%）中的缓冲液指定了标准pH值[pH*(s)]。
