Sound Velocity and Isobaric Specific Heat in the Molten System NaNO₂–NaNO₃

Abstract

Sound velocity and isobaric specific heat in the molten system Na(NO₂–NO₃) have been measured by the ultrasonic pulse-echo method and by the differential scanning calorimetry method, respectively. With these observed values and an available density, isochoric specific heat, adiabatic and isothermal compressibilities and internal pressure have been derived. These observed and derived properties of the molten system Na(NO₂–NO₃) show a good linearity with concentration. It has been conjectured that such good linearity may not be due to a similarity of ionic radii between NO₂⁻ and NO₃⁻ with comparison between the properties of the systems (Na–K)NO₃, (Na–K)(NO₂–NO₃) and Na(NO₂–NO₃).