Thermodynamic properties data of ternary system NH4Cl-NH4H2PO4-H2O at 298.15 K including the solubility data

Abstract

• Determination of the thermodynamic properties of the system {yNH4Cl+(1-y)NH4H2PO4}(aq) at 25 °C. • Application of the PSC model to describe the thermodynamic behavior of aqueous solutions. • Calculation of NH4Cl and NH4H2PO4 activity coefficients in the system {yNH4Cl+(1-y)NH4H2PO4}(aq). • Prediction of NH4Cl and NH4H2PO4 solubilities in aqueous solution. The mixed aqueous electrolyte system ammonium chloride and ammonium di-hydrogen phosphate has been studied with the hygrometric method at the temperature 298.15 K. The water activities, osmotic coefficient and solubilities are deduced from measurements of relative humidities of this system against total molality ranging from 0.4 mol . kg −1 to about saturation, and for different ionic-strength fractions y of NH 4 H 2 PO 4 ( y = I N H 4 H 2 P O 4 / [ I N H 4 H 2 P O 4 + I N H 4 C l ]) of 0, 1/4, 1/3, 1/2, 2/3, 3/4 and 1. Experimental results are compared to Dinane rule by the Extended Compound Additivity Law (ECA), Leitzke-Stoughton (LS II) and Lin et al. equation. The obtained results were correlated using the PSC model to predict the solute activity coefficients in the mixture for different compositions of the system and are also used to calculate the solubility and excess Gibbs energy in the studied molality range.