3ESO. Osmosis.

Osmosis is the spontaneous net movement of solvent molecules through a partially permeable membrane into a region of higher solute concentration, in the direction that tends to equalize the solute concentrations on the two sides.

** You need to know… In a solution, we have solvent in a major proportion; and solute, in a minor proportion. In your Colacao, milk is the solvent, and colacao is the solute. A solvent is a substance which dissolves a solute. When a solvent dissolves into a solute, it creates a solution.

Depending on the relative concentrations in both sides of the membrane, we classify these systems in:

• Hypertonic: the environment concentration is higher than the cell one. The cell “gives” water to the enviroment trying to balance both concentrations, to dilute the outer solution.
• Isotonic: Both concentrations are the same.The same numer of water molecules goes out and come into the cell.
• Hypotonic: The environment concentration is lower that the cell one. So the cell “absorbs” water to dilute its own concentration.

Osmosis video.
Say if the following sentences are true or false, and say why.

1. The process of osmosis regulates the amount of water that comes in or goes out from cells.
2. Particles are able to go through the membrane depending on their size or polarity.
3. Hypertonic solution means low concentration of salts in a solution.
4. Cells in a hypotonic solution tend to absorb water through their membranes.
5. To balance concentrations, salt molecules soak through the membrane.
6. When both environments are isotonic, no water molecule go through the membrane.