For example, for a 12'x25' single-car driveway with a 9 bed of gravel (in three layers), convert 9 to 0.75'; multiply 0.75 x 12 x 25, which equals 8.34 cubic yards, or roughly 10-14 tons. A 4 layer of gravel to resurface an existing 12'x25' driveway requires about 2.78 cubic yards or roughly 3.33-4.73 tons.
Diffusion [edit]. Diffusion of KMnO4 in water. Diffusion is the process of a substance spreading out to evenly fill its container or environment. In a solution, a concentrated solute diffuses to spread evenly in its solvent. In air, gas molecules diffuse to mix thoroughly. Substances diffuse from areas of high concentration to low concentration.
Diffusion is the chemical & biological process when molecules from a material move from an area of high concentration (where there are lots of molecules) to an area of low concentration (where there are fewer molecules).