What factors affect rate of diffusion? What factors affect the rate of osmosis?

Several factors affect the rate of diffusion of a solute including the mass of the solute, the temperature of the environment, the solvent density, and the distance traveled.

the rate of diffusion is directly proportional to the concentration gradient. The greater the difference in concentration between two areas, the greater the rate of diffusion. Thus, when the gradient is zero, there will be no net diffusion, diffusion will only occur so long as a concentration gradient exists;

the rate of diffusion is indirectly proportional to resistance. In other words, the greater the resistance to diffusion, the lower the rate of diffusion. Resistance refers to anything that reduces the rate of diffusion such as the partition in our perfume example. The width of the partitions is a resistance; the wider the partitions, the lower the resistance. And, the membrane is a resistance to the movement of ions and other charged substances in or out of cells; and

the rate of diffusion is inversely proportional to distance traveled (also a function of resistance). For example, some typical diffusion rates for water are 10 µm - 0.1 sec; 100 µm -1 sec; and 1 mm - 100 sec. As the text demonstrates nicely, diffusion is effective over short distances, but is pathetically slow over long distances.

The rate of diffusion is directly proportional to temperature; and

The rate of diffusion is indirectly related to molecular weight (heavier particles move more slowly than lighter, smaller ones). At room temperature, the average velocity of a molecule is fast - about 2 km/sec (=3997 mph!).

Temperature increases the rate of molecular movement, therefore, increases the rate of diffusion.

Pressure increases the speed of molecules, therefore, increase the rate of diffusion.

Solute particles decrease the free energy of a solvent. Essentially solvent molecules, such as water in a biological system, move from a region of greater mole fraction to a region where it has a lower mole fraction.

1) Temperature because a faster temp means a faster rate of reaction

2) Concentration (water potential level) in osmosis molecules have to move from an area on high water potential to an area of low water potential.also the area of low water potential will contain more sugar molecules than water molecules and the area with a high water potential will contain less sugar molecules than water molecules, meaning that the sugar molecules will moves from the area of low water potential to the area of high water potential. so it's sort of like the two sides are swapping molecules until they're equal. this increase the rate of osmosis if the high water potential side and the low water potential side have a very different level of water, but it will slow down as they share out the water and sugar molecules.

3) The distance the molecules have to move across. so the more distance between the two sides the slow the rate of osmosis.