Osmotic coefficient

Osmotic coefficient is a measure of how hard it is for something to move in or out of something else. Imagine a container that has two sides, one side with clean water (like a glass of water) and one side with sugary syrup or another type of sticky liquid. The sides are separated by a thin barrier. If we put a small ball into the clean water side, it will float up and move through the barrier and into the sugary syrup. But it will be much harder for the ball to move from the syrup side back into the clean water. The osmotic coefficient is a measure of how hard it is to move from one side to the other.