Osmosis

What is osmosis?

The net movement of water molecules across a partially permeable membrane from a region of higher water concentration (lower solute concentration) to a region of lower water concentration (higher solute concentration)

What is a partially permeable membrane?

One with very small holes in it - so small, that only tiny molecules (like water) can pass through them

What can’t pass through a partially permeable membrane?

Bigger molecules (e.g. sucrose)

How do the water molecules in osmosis pass?

Both ways through the membrane because water molecules move about randomly all the time

Why is there a steady net flow (the overall movement of particles in one direction after considering movement both ways) of water into the region with fewer water molecules?

Because there are more water molecules on one side than on the other, causing water to move towards the region with fewer molecules - meaning the solute solution gets more dilute, the water acts like it’s trying to ‘even up’ the concentration either side of the membrane