TERNARY SOLUTION MUTUAL DIFFUSION-COEFFICIENTS AND DENSITIES OF AQUEOUS MIXTURES OF SUCROSE WITH NACL AND SUCROSE WITH KCL AT 25-DEGREES-C

Ternary solution isothermal mutual diffusion coefficients (interdiffus ion coefficients) have been measured for aqueous mixtures of 0.250 mol -dm(-3) sucrose (component 1) with 0.5 and 1.0 mol-dm(-3) NaCl or with 0.5 and 1.0 mol-dm(-3) KCl (salt = component 2) at 25.00 degrees C us ing Rayleigh interferometry with computerized data acquisition. Densit ies were also measured. The volume-fixed diffusion coefficients (D-ij) (v) show the following characteristics. At all compositions (D-21)(v) is much larger than (D-12)(v) and (D-21)(v) is a fairly significant fr action (33 to 68%) of (D-11)(v). In addition, (D-12)(v) is slightly la rger for mixtures containing NaCl than for those containing KCl at the same concentration, whereas (D-21)(v) is significantly larger for mix tures containing KCl. Values of (D-11)(v) are slightly larger for solu tions containing KCl than for solutions containing NaCl. The observed trends imply that (D-21)(v) will probably exceed (D-11)(v) in both mix tures if concentrations of NaCl or of KCl are increased much further w hile maintaining the sucrose concentration at 0.250 mol-dm(-3). Finall y, the solvent-fixed cross-term diffusion coefficients (D-12)(0) and ( D-21)(0) are significantly larger than their corresponding (D-12)(v) a nd D-21)(v).