TERNARY SOLUTION MUTUAL DIFFUSION-COEFFICIENTS AND DENSITIES OF AQUEOUS MIXTURES OF NACL AND NA2SO4 AT 298.15 K FOR 6 DIFFERENT SOLUTE FRACTIONS AT A TOTAL MOLARITY OF 1.000 MOL-CENTER-DOT-DM(-3)
Jg. Albright et al., TERNARY SOLUTION MUTUAL DIFFUSION-COEFFICIENTS AND DENSITIES OF AQUEOUS MIXTURES OF NACL AND NA2SO4 AT 298.15 K FOR 6 DIFFERENT SOLUTE FRACTIONS AT A TOTAL MOLARITY OF 1.000 MOL-CENTER-DOT-DM(-3), Journal of chemical and engineering data, 43(4), 1998, pp. 668-675
Isothermal mutual diffusion coefficients (interdiffusion coefficients)
were measured for ternary aqueous mixtures of NaCl and Na2SO4 at a co
nstant total molarity of 1.000 mol . dm(-3) and 298.15 K. Measurements
were performed using Rayleigh interferometry with computerized data a
cquisition at NaCl molarity fractions of z(1) = 1, 0.90, 0.75, 0.50, 0
.25, and 0. Densities of the solutions were measured with a vibrating
tube densimeter. At all ternary solution compositions, one cross-term
diffusion coefficient has negative values whereas the other has positi
ve values. These measurements supplement our earlier results at 0.500
mol . dm(-3). Both main-term diffusion coefficients are significantly
smaller at 1.000 mol . dm(-3) than at 6.500 mol . dm(-3) at any fixed
value of z(1), whereas both cross-term coefficients are shifted in a p
ositive direction. Trace diffusion coefficients D(Cl-) and D*(SO42-)
were extrapolated from these results for the Cl-(aq) ion in 1.0 mol .
dm(-3) Na2SO4(aq) and for the SO42-(aq) ion in 1.0 mol . dm(-3) NaCl(a
q). Values of D(Cl-) in Na2SO4(aq) and in NaCl(aq) were found to be e
ssentially identical, as were D(SO42-) in these same two electrolytes
, provided the comparisons were made at the same volumetric ionic stre
ngths.