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研究了298.15和323.15K广泛浓度范围内四硼酸钾溶液pH,并根据化学反应平衡常数和牛顿迭代法计算获得了溶液化学物种分布图.典型样品用拉曼光谱进行核实.研究表明,高浓溶液中存在主要化学物种是B4O5(OH)24-,次要化学物种是B3O3(OH)4-和B(OH)4-.用X射线散射法研究了298和323K高浓四硼酸钾溶液结构.用几何模型定量描述B4O5(OH)42-,B3O3(OH)-4和B(OH)-4离子内、离子间、分子间的相互作用,并用最小二乘法进行精修.模型计算和精修给出硼氧六元环内原子间距和配位数,并与晶体结构很好一致,表明高浓溶液中离子内有序程度较高.同时给出K+和硼酸根离子水合数和水合距离,以及接触离子对的结构信息,并进一步简单讨论温度和浓度变化对溶剂结构的影响.
The pH values of potassium tetraborate solution in a wide range of concentrations of 298.15 and 323.15K were studied and the distribution of chemical species was obtained according to the chemical reaction equilibrium constant and Newton’s iterative method.The typical samples were verified by Raman spectroscopy.The results showed that the high concentration solution The main chemical species is B4O5 (OH) 24-, and the secondary chemical species is B3O3 (OH) 4- and B (OH) 4-. The structures of 298 and 323K highly concentrated potassium tetraborate solutions were investigated by X-ray scattering. The geometrical model was used to quantitatively describe the intermolecular and intermolecular interactions between B4O5 (OH) 42-, B3O3 (OH) -4 and B (OH) -4 ions and to perform the least-squares refinement. The atomic distances and coordination numbers in six-membered ring of boroxine are given, which are in good agreement with the crystal structure, indicating that there is a high degree of order in the ions in the highly concentrated solution. At the same time, hydration numbers and hydration distances of K + and borate ions are given, As well as the structure information of contact ion pairs, and further briefly discuss the effect of temperature and concentration changes on the solvent structure.