Astonishing Diffusion

Diffusion is the movement of something from an area of high concentration to a lower concentration.

Imagine a long rectangular box with a wall in the middle separating the two sides. Crammed in one side is a huge swarm of bumble bees all travelling in random directions; the other side is empty. Now, if we remove the wall, what will happen?

By User:Img (Self-photographed) [GPL (], via Wikimedia Commons

Easy! The bees will spread out evenly into the whole box. This is a basic example of diffusion, and you would be surprised how commonly it is employed in the world around us. Where there are areas of different temperature or pressure, nature always acts to balance up these areas if possible, creating a more stable environment. Add hot water to a cold bath and the heat will diffuse, spreading the energy evenly to create the perfect temperature as opposed to having a layer of hot water above a layer of cold.

You might have realized that when you cook pasta in boiling water, it expands. This is because water molecules are diffusing into the pasta shapes, making them larger and more flexible. And while we are in the kitchen, it’s not long after you’ve ashamedly burnt the dinner that your family can see and smell the smoke – thanks again to diffusion!

This next example shows how diffusion is used to supply oxygen to all of the cells in our body. Fresh oxygen sent from our lungs into our blood stream diffuses through the wall of the cell. At the same time, waste carbon dioxide is diffusing back into the blood stream, ready to be sent back to the lungs and breathed out again!

It appears diffusion is everywhere!

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Posted in Activity, Biology, Chemistry