MEAN ACTIVITY-COEFFICIENTS IN THE TERNARY NACL-NANO3-H2O AND NABR-NANO3-H2O SYSTEMS AT 298.15-K

The mean activity coefficients of NaCl in the NaCl-NaNO3-H2O system and NaBr in the NaBr-NaNO3-H2O system have been measured at 298.15 K over the range of ionic strengths from 0.3 to 6 m. The measurements were made by an electrochemical cell using ion-selective electrodes (ISE). The data were collected with an Orion millivolt (mV) meter, Model EA 920, using Na-ISE against Cl-ISE and Br-ISE as reference electrodes. The experimental mean activity coefficients of NaCl and NaBr obey Harned's Rule. The mean activity coefficients of NaNO3 were calculated by using the Gibbs-Duhem equation.