Speeds of Sound and Viscosities of Potassium Thiocyanate in Water, Methanol, and Propylene Carbonate

Abstract

Measured speeds of sound, structural relaxation times, and the viscosities of aqueous, methanolic, and propylene carbonate solutions of potassium thiocyanate are reported as functions of concentration (0.0049 ≤ m/mol kg^–1 ≤ 22.924) and temperature (273.15 ≤ T/K ≤ 343.15). The primary solvation number of the SCN^– ion has been estimated to be 11.6 in a water medium. The total solvation numbers corresponding to the concentration at which the isentropic compressibility isotherms converge for potassium thiocyanate in methanol and propylene carbonate media were estimated to be 5.2 and 1.9, respectively. Structural transition in aqueous potassium thiocyanate solution has been observed in the concentration range of c. 4.0–5.5 mol kg^–1 which was assigned due to the counterbalance between the structural-breaking effect of the K⁺ ion and the ion-association of K⁺ and SCN^– ions.