Instabilities in free diffusion boundaries of NaCl-sucrose-H2O solution at 25°C

The four diffusion coefficients for the system sucrose (0.097M)-NaCl-(0.291M)-water at 25°C have been measured by the Gouy interferometric technique. The cross terms D₁₂ and D₂₁ are small However, if sucrose or NaCl are chosen as component 3 instead of water, one of the cross terms becomes very large. Several runs were used to test the McDougall analysis of gravitational instability in diffusion boundaries for three component systems. Growth of convective motions at the center and at the edges of the boundary have been observed that confirm the McDougall model.