How can diffusion be demonstrated experimentally?

Diffusion can be experimentally demonstrated using a simple setup involving a beaker, water, and food colouring.

To begin with, you need a clear beaker or glass filled with water. The water should be still and at room temperature. Then, carefully add a drop of food colouring to the water, preferably in the centre of the beaker. It's important not to stir or shake the water. Over time, you will observe that the colour from the food dye slowly spreads out, eventually colouring all the water. This is diffusion in action.

The food colouring, made up of tiny particles, moves from an area of high concentration (where the drop was added) to an area of low concentration (the rest of the water). This movement continues until the particles are evenly distributed throughout the water, which is when we say equilibrium has been reached.

This experiment can also be conducted using different temperatures of water. You will notice that the food colouring diffuses faster in warm water compared to cold water. This is because the particles have more kinetic energy in warm water, and therefore move faster.

Another way to demonstrate diffusion is by using agar blocks and hydrochloric acid. The acid is placed in a petri dish and the agar block is placed in the centre. Over time, the acid diffuses into the agar block, turning it from pink to colourless. The rate of diffusion can be measured by timing how long it takes for the agar block to lose its colour.

These experiments visually demonstrate the process of diffusion, showing how particles move from areas of high concentration to areas of low concentration until equilibrium is reached.