  A diffusive model of osmosis is presented that explains currently available
experimental data. It makes predictions that distinguish it from the
traditional convective flow model of osmosis, some of which have already been
confirmed experimentally and others have yet to be tested. It also provides a
simple kinetic explanation of Raoult's law and the colligative properties of
dilute aqueous solutions. The diffusive model explains that when a water
molecule jumps from low to high osmolarity at equilibrium, the free energy
change is zero because the work done pressurizing the water molecule is
balanced by the entropy of mixing. It also explains that equal chemical
potentials are required for particle exchange equilibrium in analogy with the
familiar requirement of equal temperatures at thermal equilibrium.
