【摘要】 采用等温溶解法测定了偏钒酸铵NH₄VO₃在NH₄H₂PO₄-H₂O和（NH₄）₃PO₄-H₂O体系中T=298.15-328.15 K时的溶解度以及溶液的密度和p H值。结果表明,NH₄VO₃的溶解度随着（NH₄）₃PO₄或NH₄H₂PO₄溶液浓度的增大,先降低后升高,这是由于同离子效应、化学反应平衡及离子活度的共同作用。比较T=298.15K时,NH₄VO₃分别在NH₄H₂PO₄-H₂O、（NH₄）₂HPO₄-H₂O和（NH₄）₃PO₄-H₂O体系中溶解度,发现在相同的磷酸盐浓度下NH₄VO₃的溶解度在NH₄H₂PO₄-H₂O体系中最大,在（NH₄）₃PO₄-H₂O体系中居中,在（NH₄）₂HPO₄-H₂O体系中最小。进一步地,在T=298.15 K和磷酸盐浓度C=0.5 mol?kg-1时,结合pH值和反应溶度积常数K SP等计算三个体系中的平均离子活度系数（γ±）,发现γ±值在（NH₄）₂HPO₄-H₂O体系中最大,在（NH₄）₃PO₄-H₂O体系中居中,在NH₄H₂PO₄-H₂O体系中最小,与溶解度规律一致。更多还原

【Abstract】 The solubility of ammonium metavanadateNH₄VO₃ in NH₄H₂PO4_-H₂O and（NH₄）₃PO₄-H₂O systems at T = 298.15-328.15 K was measured using the classic isothermal dissolution method. The densities and p H values of the solutions were also determined. The solubility of NH₄VO₃ decreased at first and then increased with increasing NH₄H₂PO₄or（NH₄）₃PO₄concentrations. This was considered to be caused by the common ionic effect, chemical reaction equilibrium and ionic activity. At T = 298.15 K, the solubility of NH₄VO₃ in the NH₄H₂PO₄-H₂O system was the highest, and was lower in the（NH₄）₃PO₄-H₂O system. The solubility in the（NH₄）₂HPO₄-H₂O system was the lowest. The mean ionic activity coefficients were calculated for the three phosphate solutions at C = 0.5 mol?kg-1using the p H values and dissolution reaction constant. The mean ionic activity coefficients were the largest for the（NH₄）₂HPO₄-H₂O system, and were smaller for the（NH₄）₃PO₄-H₂O system. The mean ionic activity coefficients were the smallest for the NH₄H₂PO₄-H₂O system, which agrees with the solubility variations of NH₄VO₃ in the three phosphate systems.更多还原