Volumetric Properties and Ion Interactions for Sodium Hypophosphite Aqueous Solution from 283.15 to 363.15 K at 101.325 kPa

Abstract

Densities of sodium hypophosphite aqueous solution (NaH2PO2) with the molality varied from 1.019143 to 10.43887 mol kg–1 at temperature intervals of 5 K range from 283.15 to 363.15 K at 101.325 kPa were measured by a precise Anton Paar Digital vibrating-tube densimeter. From the density data, the thermal expansion coefficients, apparent volume and partial molar volumes were obtained. According to the Pitzer ion-interaction equation of the apparent molar volumes, the Pitzer single-salt parameters and their temperature-dependent correlation for NaH2PO2 were firstly obtained by the least-squares method. The model shown that apparent molar volumes agree well with the experimental values, which indicated the single salt parameters and the temperature-dependent formula are reliable.