Comparative study of density, sound velocity and refractive index for (water + alkali metal) phosphates aqueous systems at T = (298.15, 303.15, and 308.15) K

The density, speed of sound and refractive index for (water + alkali metal) (Li, Na and K) were measured over their entire composition range at T = (298.15, 303.15 and 308.15) K. The isentropic compressibility, change and relative change in isentropic compressibility, apparent molal compressibility, acoustic impedance, speed of light and molar refractions were calculated using values of the experimental density, speed of sound, and refractive index, respectively. Redlich–Kister smoothing linear equation was used for obtaining limiting sound velocity, isentropic compressibility and refractive index data. Ion–ion, ion-dipolar, solute–solvent and intermolecular interactions have been interpreted with thermodynamic properties.

Graphical abstractFigure shows a comparative study where sound and light velocity of AMPS in aqueous medium, both are inversely proportional. This study having opposite trend of light and sound velocities shows energy conservation because both the sound and light are form of energy.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Thermodynamic study of aqueous alkali metal salts. ► Isentropic compressibility with internal pressure. ► Aqueous alkali metal salt as buffer. ► Aqustic impendence. ► Sound and light velocity in opposite manner.