In this video, we're going to briefly define diffusion. Diffusion is really just the net movement of a substance from an area of high concentration down to an area of low concentration. Molecules have a natural tendency to diffuse with or down their concentration gradient, which means that the molecule is diffusing from an area of high concentration to an area of low concentration.
If we take a look at our image down below, we'll be able to see an example of the diffusion of red dye in water. Notice in this image we're showing you this beaker and all of the blue water molecules are represented by these blue circles, and the red circles represent dye molecules. On the far left over here, we have a person's hand, and they are adding a drop of red dye to this beaker of water. Initially, at the very beginning of this timescale on the far left, when this drop of red dye is added, it is highly concentrated in one area, and we can see this area has a high dye concentration. But notice that other areas of the beaker, such as over here and over here and right here, have a low dye concentration. In fact, there's no dye in one region initially. However, over time, we know that molecules have this natural tendency to diffuse with or down their concentration gradients from an area again of high concentration to an area of low concentration. We expect these red dye molecules to diffuse to these other surrounding areas that have lower dye concentration. This is exactly what begins to happen as time progresses.
This diffusion from high to low concentration will continue to occur until equilibrium has been reached. Equilibrium is when all the red dye particles are evenly distributed throughout the beaker so that each area of the beaker has an equal dye concentration. This concludes our brief discussion on diffusion, and we'll be able to get some practice applying these concepts and learn more as we continue to move forward. So, I'll see you all in our next video.