Diffusion

Definition

Diffusion is the process by which gas molecules spread from an area of higher concentration to an area of lower concentration. It occurs due to the random motion of gas particles.

5 Must Know Facts For Your Next Test

1. Diffusion rates depend on the temperature; higher temperatures increase diffusion rates.
2. Lighter gas molecules diffuse faster than heavier gas molecules.
3. The diffusion rate can be described mathematically using Fick's laws of diffusion.
4. Graham's law states that the rate of diffusion is inversely proportional to the square root of the molar mass of the gas.
5. Diffusion can be observed in both homogeneous and heterogeneous mixtures.

Review Questions

• How does temperature affect the rate of diffusion?
• According to Graham's law, how does molar mass influence the rate at which a gas diffuses?
• What role does molecular weight play in the diffusion process?

Related terms

Effusion:

Effusion is the process by which gas molecules escape through a small hole into a vacuum.

Graham’s Law: $$\text{Graham's Law}$$ states that the rate of effusion or diffusion of a gas is inversely proportional to the square root of its molar mass.

Kinetic Molecular Theory:

$$\text{Kinetic Molecular Theory}$$ explains that gas particles are in constant, random motion and that this motion results in properties such as pressure and temperature.