Study of Osmosis


Our objective is that to study osmosis using a potato osmometer.


What is Osmosis?

Osmosis is the process in which solvent molecules moves through a semi-permeable membrane from a region of higher concentration to a region of lower concentration until the amount of fluid is equalised on both sides of the semipermeable membrane.  

The fluid that passes through the semipermeable membrane is known as the solvent, while the dissolved substance in the fluid is known as the solute.  The mixture of solvent and solute makes up a solution.


Cause for Osmosis

Osmosis occurs due to the free energy of the solvent molecule in two regions. Pure water or solvent has more free energy compared to that present in a solution. Therefore during osmosis, solvent or water moves through the semipermeable membrane from a region of its high free energy to a region of its low free energy.

Importance of Osmosis

Osmosis plays a critical role in plant and animal cells.  It helps in the distribution of nutrients and in the release of waste products. The living cells of both plant and animals are surrounded by a semipermeable membrane known as the cell membrane. The membrane forms a selective barrier between the cell and its environment and does not allow toxic substances from the surroundings to enter into the cell. The selective permeability allows the cell to regulate the flow of necessary substances into and out of the cell. In plants osmosis is also responsible for absorbing water and minerals from the soil by using the semipermeable membrane of the root.

Types of Solutions

Hypotonic Solution

These are solutions with low solute levels.

Hypertonic Solution

Solutions with high solute levels are known as hypertonic.

Isotonic Solution

If both solutions have the same amount of solute concentration they are then known as isotonic solution.

Occurence of Osmosis in Different Solution Types

Hypotonic Solution

If we place living cells in a hypotonic solution the water moves into the cell because of the higher concentration of water than in the cell.  The cell then swells to become turgid.

Hypertonic Solution

If we place living cells in a hypertonic solution the water moves out of the cell because of the lower concentration of water than the cell. The cell then shrinks and becomes plamolyzed.

Isotonic Solution

If we place living cells in an isotonic solution, it won’t show any change because of the equal concentration of water on either side. The cell remains as it is. 

The phonomenon of osmosis can be demonstrated using an osmometer, a device that shows the occurrence of osmosis.

Learning Outcomes

  • Students understand the concept of osmosis.
  • Students understand the cause for osmosis.
  • Students understand the importance of osmosis in plant and animal cells.
  • Students will be able to do the experiment more accurately in the real lab once they understand the steps through the animation and simulation.