Osmotic and activity coefficients of aqueous solutions of KCl at temperatures of 283.15, 288.15, 293.15 and 298.15 K: A new isopiestic apparatus

Osmotic coefficients of aqueous KCl solutions have been determined by the isopiestic method using standard NaCl reference solutions for comparison. Measurements were made at 283.15, 288.15, 293.15, and 298.15 K. A modified isopiestic apparatus is described. Equilibrium times ranged from 4 to around 15 days. The equilibrium molalities went up to 1.0 m. The average relative uncertainty of the observed water activities of the solutions was less than 0.005%. The activity and osmotic coefficients of KCl aqueous solutions at several temperatures are compared with literature data.