There are 4 factors which determine the rate of diffusion:
- The stepness of the concentration gradient (the bigger the difference between two sides of membrane, the quicker the rate of diffusion);
- Temperature (higher temperatures give molecules more kinetic energy, molecules moving around faster, so diffusion is faster);
- The surface area ( more molecules can cross a greater area of membrane, any time);
- The type of molecule diffusing (large molecules need more energy to move, so they move slowly; non-polar molecules diffuse mor easily than polar molecules).