Whats the difference between osmosis and diffusion?
Diffusion is the spread of “stuff” away from high concentration areas to low concentration areas. Diffusion continues until concentrations have become equalised… Diffusion can occur whether the stuff is in vacuum or in solution… If the stuff is small enough it will spread even through the gaps in an apparent “barrier”, in which case the barrier is called permeable because the stuff can get through (and will on average travel from high concentration areas and to low concentration areas as usual). An interesting thing happens when a) There’s stuff in solution (i.e. the stuff is a solute in a solvent); and b) There’s a barrier with only small gaps in it. By small gaps we mean that the molecules of stuff can’t get through but the molecules of water (or other solvent in which the stuff is dissolved) can get through: Such a barrier is called semi-permeable… In these circumstances the concentrations of stuff cannot become equalised through diffusion of stuff because we’ve set things up
