三元体系Na_3PO_4—H_2NCONH_2—H_2O298K相平衡及平衡液相物化性质研究

Experimental Study on the Phase Equilibrium of the Ternary System NaVO_3—H_2NCONH_2—H_2O at 298K and Physicochemical Properties of Equilibrium Liquid Phase

采用等温溶解平衡法测定了三元体系Na3PO4—H2NCONH2—H2O 298K下的溶解度及平衡液相物化性质(密度、电导率、pH值),绘制出了相应的溶解度等温图和物化性质—组成图。此三元体系等温溶解度图属简单共饱型,未产生新的复盐和固溶体。两个结晶区分别对应为盐Na3PO4.8H2O和H2NCONH2。无变量点平衡液相组成为:w(Na3PO4.8H2O)1.49%,w(H2NCONH2)25.41%,对应的平衡固相盐为Na3PO4.8H2O和H2NCONH2。实验结果表明,Na3PO4与H2NCONH2的溶解度相互抑制,并简要讨论了物化性质的变化规律。

The solubilities and physicochemical properties（density,conductivity and pH value） of equilibrium liquid phase were determined in the ternary system Na3PO4-H2NCONH2-H2O at 298K by isothermal solution equilibrium method. According to the experimental data, the isothermal diagram and physicochemical properties-composition diagrams of the ternary system were ploted. This ternary system is a simple evtonic type, no double salt or solid solution is formed. The isotherm diagram consists of two univariant curves and two crystallization fields correspondinig to Na3PO4 · 8H2O and H2NCONH2. The composition of equilibrium liquid phase of invariant point is as follows ： w （ Na3 PO4 · 8H2O ） 1.49%, w （ H2 NCONH2 ） 25.41%. The solubility of Na3 PO4 and H2 NCONH2 inhibited with each other. The laws of physicochemical properties in the solution were discussed briefly.