Viscosities of Aqueous Solutions of Mg(NO3)2, HNO3, and Their Mixtures to High Concentrations at 298 to 328 K

Abstract

Viscosities of aqueous solutions of Mg(NO₃)₂, HNO₃, and their mixtures have been measured by capillary viscometry at temperatures T/K = 298.15, 313.15, and 328.15 at 0.1 MPa pressure. Viscosities of the binary solutions were determined at concentrations up to (4.55 and 15.00) mol·kg^–1 for Mg(NO₃)₂ (aq) and HNO₃ (aq) respectively, with an estimated relative experimental uncertainty of 0.009 to 0.013, corresponding to a 68% confidence level (equivalent to one standard deviation). Where comparisons were possible, the present results were generally in good agreement with most literature data. This enabled identification of outliers and inconsistencies in the latter. The binary solution viscosities were well fitted with simple 4-parameter empirical equations which showed limited, but useful, extrapolative capabilities with respect to concentration and, especially, temperature. Viscosities of ternary mixtures [Mg(NO₃)₂ + HNO₃ + H₂O] were measured as a function of composition at constant ionic strengths ranging from (3.00 to 12.64) mol·kg^–1 and were found to have approximately linear (pro-rata) dependences on composition. This enabled prediction of mixture viscosities with a modest level of accuracy (up to 9% but typically smaller than 5%) throughout the parametrization space without the need for mixing parameters.