Autoprotolysis in water/methanol/NaCl ternary systems

Abstract

A potentiometric method was used to determine the autoprotolysis constant for aqueous solutions containing 0, 20 and 40 weight percent of methanol in wide range of NaCl concentration at 25°C. Ionic strength was ranged between 0.25 and 2.00 mol L-1 by intervals of 0.25 units. Osmotic and activity coefficient of mixed solvents were calculated as a function of ionic strength. Dependence on ionic strength was analyzed by using the original Specific ion Interaction Theory. The specific ion interaction parameters were extracted associated with the thermodynamic autoprotolysis constant. Results indicate that interaction between ions increases with the increasing of the methanol content in mixture.

Keywords

• autoprotolysis
• water-methanol
• sodium chloride
• SIT