Speeds of sound and viscosities of potassium thiocyanate in water, methanol, and propylene carbonate

Measured speeds of sound, structural relaxation times, and the viscosities of aqueous, methanolic, and propylene carbonate solutions of potassium thio cyanate are reported as functions of concentration (0.0049 less than or equ al to m/mol kg(-1) less than or equal to 22.924) and temperature (273.15 le ss than or equal to T/ K less than or equal to 343.15). The primary solvati on 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, r espectively. Structural transition in aqueous potassium thiocyanate solutio n has been observed in the concentration range of c. 4.0-5.5 mol kg(-1) whi ch was assigned due to the counterbalance between the structural-breaking e ffect of the K+ ion and the ion-association of K+ and SCN- ions.