Abstract: This paper reports our study on thermodynamic properties of HCl+NaCl+ 2-propanol+H_2O system by means of emf measurements of the cells without liquid junction,
Pt, H_2(1atm)|HCl(m), 2-propanol(x), H_2O(1-x)|AgCl-Ag (A)
Pt, H_2(1atm)|HCl(m_A), NaCl(m_B), 2-propanol(x), H_2O(1-x)|AgCl-Ag (B)
at constant total ionic strenths I=0.5, 1.0, 2.0 and 3.0 mol kg~(-1), from 5 to 45 ℃, where m_A and m_B are the molalities of HCl and NaCl, respectively, x is the mo- lar fraction of 2-propanol in the mixed solvent, which is 0.05 during all measurements.
The standard electrode potential of Ag-AgCl in mixed solvent have been determined from equation (1) and using emf data of the cell (A) in table 1. The transfer properties of HCl have been calculated and listed in table 2. Using emf of cell (B), the activity coefficients of HCl, γ_A, in the system have determined according to equation (16).
The results show that HCl obeyes Harned Rule up to I=3.0 mol kg~(-1) over a range 15—45 ℃ (Fig.1). Under the condition of constant components of mixture, the logarithm of HCl activity coefficients, logγ_A are a linear function for reciprocal of temperatures equation (17). The primary, secondary and total medium effect of HCl have been calculated and discused (see table 5).