Final answer:
Diffusion in a warm fish tank can be showcased by dropping blue food coloring into the water, which will spread out from a high concentration to low concentration areas. The net rate of diffusion is highest at the beginning and slows as the food coloring becomes more evenly distributed until an equilibrium is reached.
Step-by-step explanation:
The phenomenon of diffusion can be easily demonstrated using a fish tank full of warm water and a droplet of blue food coloring. When a drop of the food coloring is carefully placed into the water, it will begin to spread out from the area of higher concentration, where the color is initially dropped, to areas of lower concentration. This spreading occurs because of the random molecular motion of the food coloring particles.
Initially, the net rate of diffusion is highest, as there is a significant concentration gradient between the drop of food coloring and the surrounding water. As time passes, the molecules continue to move randomly, and the food coloring becomes less concentrated at the source; it continues to spread until the concentration of the food coloring is uniform throughout the tank, at which point equilibrium is achieved.