How is diffusion demonstrated in a laboratory setting?

Diffusion can be demonstrated in a laboratory setting through simple experiments involving liquids or gases.

One common way to demonstrate diffusion in a laboratory setting is through the use of liquids. This can be done by adding a drop of food colouring to a beaker of water. Over time, the colour will spread throughout the water, demonstrating the process of diffusion. This happens because the molecules of the food colouring move from an area of high concentration (the drop) to an area of low concentration (the water) until equilibrium is reached. This experiment can be done at different temperatures to show how temperature affects the rate of diffusion, with higher temperatures leading to faster diffusion.

Another way to demonstrate diffusion is through the use of gases. This can be done by opening a bottle of perfume in one corner of a room. After a while, the scent will spread throughout the room, demonstrating diffusion. This happens because the perfume molecules move from an area of high concentration (the bottle) to an area of low concentration (the rest of the room) until equilibrium is reached. This experiment can also be done in different room sizes to show how the size of the space affects the rate of diffusion.

A more specific experiment involves the use of hydrochloric acid and ammonia. A cotton wool soaked in hydrochloric acid is placed at one end of a glass tube, and another cotton wool soaked in ammonia is placed at the other end. Over time, a white ring of ammonium chloride forms in the tube, showing where the two gases have met and diffused. This experiment clearly demonstrates diffusion as it shows the movement of particles from areas of high concentration to areas of low concentration.