Question

What is diffusion? Explain factors affecting the rate of diffusion.

Answer 1

Diffusion is the net movement of molecules or atoms from a region of high concentration to a region of low concentration as a result of random motion of the molecules or atoms.  Temperature increases the kinetic energy of the molecule so it moves faster and hence the rate of diffusion increases. the more the concentration gradient the higher the driving force of the process and hence the higher the rate of diffusion.

Answer 2

Diffusion is the movement of particles from one place to another due to a difference in concentration of that particle (the concentration gradient). So fundamentally, diffusion is driven by the concentration gradient. As diffusion occurs, the concentration gradient decreases, hence decreasing the driving force for diffusion. 
Other factors that affect diffusion arw those that affect the movement of the particles. One of these is temperature - the higher the temperature, the more kinetic energy the particles have, hence they move/diffuse faster. The other factor is the permeability of the particle in the medium it is moving in (i.e. a number that describes how easily the particles can move through the medium). The higher the permeability, the faster diffusion occurs.
Fick's first law of diffusion describes combines the effects of concentration gradient and permeability (in the form of a factor called diffusivity). The effect of temperature is incorporated into the diffusivity.
Fick's second law of diffusion describes how the driving force changes with time......


The rate of diffusion is affected by mass, size, charge, pressure, temperature, concentration, solubility and state of matter.

There must be other factors as well