1.24b, d. Concentration dependence of binary liquid diffusivities.
a) Estimate the diffusivity of ethanol in water at 298 K when the mol fraction of ethanol in solution is 40%. Under these conditions (Hammond, B. R., and R. H. Stokes, Trans. Faraday Soc., 49, 890, 1953):
The experimental value reported by Hammond and Stokes (1953) is 0.42 ´ 10-5 cm2/s.
Solution
Estimate the infinite dilution diffusivity of ethanol in water at 298 K
from Hayduk-Minhas for aqueous solutions
From Appendix A, the infinite dilution diffusivity of water in ethanol
at 298 K is
b) Estimate the diffusivity of acetone in water at 298 K when the mol fraction of acetone in solution is 35%. For this system at 298 K, the activity coefficient for acetone is given by Wilson equation (Smith, J. M., et al., Introduction to Chemical Engineering Thermodynamics, 5th ed, McGraw-Hill Co., Inc., New York, NY, 1996):
Solution
Estimate the thermodynamic factor
From Appendix A
Estimate the infinite dilution diffusivity of acetone in water at 298 K
from Hayduk-Minhas for aqueous solutions