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采用等温溶解平衡法研究了三元体系NaBr-Na2B4O7-H2O在373 K时的相平衡关系,并测定了饱和溶液的溶解度及密度。研究发现:该三元体系为简单共饱和型,无复盐及固溶体形成。根据溶解度数据绘制了相应的平衡溶解度曲线,相图中有1个共饱点,2条单变曲线,2个平衡固相分别为NaBr和Na2B4O7·5H2O;对不同温度条件下的溴化钠和硼酸钠的溶解度做了对比分析和讨论,结果表明,随着温度的增加,硼酸钠和溴化钠的溶解度均增大,但是在高温条件下,硼酸钠其溶解度数据增加明显;在该三元体系中溴化钠对硼酸钠有明显的盐析作用;并简要讨论了密度变化规律。
The isobaric dissolution equilibrium method was used to study the phase equilibrium of the ternary system NaBr-Na2B4O7-H2O at 373 K, and the solubility and density of the saturated solution were also determined. It is found that the ternary system is a simple and saturated type with no salt and solid solution. According to the solubility data, the corresponding equilibrium solubility curves were plotted. One phase was found in the phase diagram, two univariate curves and two equilibrium solid phases were NaBr and Na2B4O7.5H2O respectively. Under the different temperature conditions, The solubility of sodium borate is compared and discussed. The results show that the solubility of sodium borate and sodium bromide increases with the increase of temperature, but the solubility of sodium borate increases obviously under high temperature. Sodium bromide has obvious salting-out effect on sodium borate in the system; and the density variation law is briefly discussed.