Diffusion Coefficients: Self-Diffusion and Suspended Particles

This lecture covers the calculation of diffusion coefficients for self-diffusion and suspended particles. Starting with the estimation of self-diffusion coefficients for individual molecules in a fluid, the instructor explains the relationship between step size, velocity, and diffusion coefficient. The lecture then delves into the derivation of the diffusion coefficient for suspended particles, emphasizing the impact of fluid properties like viscosity. The discussion includes the application of the Stokes-Einstein relation and the derivation of the diffusion equation from a continuum perspective, focusing on mass conservation and Fick's law. The lecture concludes by highlighting the general form of a differential conservation law and the diffusion equation, setting the stage for further exploration of steady-state and time-dependent solutions.