What occurs when there is a higher concentration of molecules on one side of a membrane and the molecules flow to the other side to balance the concentration?

diffusion

Explanation:

The concept of diffusion states that molecules like to travel from areas of high concentration to low concentration.

Let's think about an example. Let's say you are having a party at your house and in one room there is 100 people and in the other room connected to it, there is only 10 people. What do you think is going to happen as time passes? Right, people are going to move to the room where there is less people so as to equally disperse themselves across the area. The same thing happens within our body with ions and gases.

Ions can diffuse into or out of cells based off their concentration gradients. If there are too many ions on one side, they will simply move to the other side. There are different types of diffusion. Passive diffusion and facilitated diffusion, but those are for a different conversation.