Question

What is diffusion? What does it have to do with osmosis?

Answer 1

Diffusion is molecules moving from a position where they are in high concentration to an area where they are at lower concentration. People talk about concentration gradients ie the molecules move down to lower concentrations. The molecules move about in solution due to Brownian motion but if they move to a lower concentration then this is energetically favorable since the entropy increases.

Osmosis is the movement of solvent molecules across a partially permeable membrane to equalise solute concentration - if you had very salty water on one side and pure water on the other the pure water side would lose water molecules until both sides were equally salty. The salty side would swell up if the sides of the container were flexible. I think dry wood swelling up when placed in water would be an example. I think movement of molecules is the basis of both and entropy increases when wood swells or water moves into a salty solution.

Answer 2

Thanks

Answer 3

You're welcome - anything else I can help with?