Diffusion - Topic 3.1

Objective: State that the energy for diffusion comes from the kinetic energy of molecules and ions.

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration. This movement occurs because of the random motion of particles.

Kinetic Energy and Diffusion

All matter is in constant motion. This motion is described by kinetic energy. The kinetic energy of particles is directly related to their temperature. Higher temperature means higher kinetic energy, and therefore faster movement of particles.

In a system with a concentration gradient, particles in the area of higher concentration have more collisions with the surrounding particles. This random movement, driven by their kinetic energy, causes particles to spread out into the area of lower concentration. The net result is the dispersal of particles from areas of high concentration to areas of low concentration.

Explanation

The energy required for a particle to move against a concentration gradient comes from its kinetic energy. Particles are constantly in random motion. When a concentration gradient exists, the particles in the high concentration area have more kinetic energy to overcome the resistance and move into the low concentration area. This is why diffusion occurs down the concentration gradient.

Table summarizing the relationship

Therefore, the energy for diffusion is supplied by the kinetic energy of the molecules and ions involved.