Osmotic pressure refers to the force that is applied to a solution when trying to stop the flow of solvent through a semipermeable membrane.
Osmotic pressure is the level of force that must be applied to a solution when it is necessary to stop the flow of solvent through a membrane with semipermeable characteristics . This particularity is very important to understand the relationships established between the liquids that are part of living beings.
The consequence of applying compression or squeezing something is known as pressure. These verbs describe activities such as tightening, tightening, crowding, or squeezing. This means that a pressure is a force that is directed at a thing. The term is also used to name a physical root magnitude that accounts for the force exerted by an object or element with respect to the unit area.
Osmotic , for its part, is a word that refers to that which belongs to or is related to osmosis (the name given to the physical-chemical phenomenon that involves the passage of solvents, although not solute, between two solutions that have different concentrations and which are separated by a semipermeable membrane).
How osmotic pressure works
The semipermeable membrane allows solvent molecules to pass but prevents solute molecules from advancing. This causes the solvent molecules to diffuse and move from a solution with a lower concentration to another with a higher concentration.
When there is no net exchange of solute between different portions of the same solution, an equilibrium osmotic pressure is said to exist. In cases where there is a membrane that protects the solution, the equilibrium osmotic pressure is achieved when the atmospheric pressure equals the pressure that the solvent exerts on the membrane.
The notion of osmotic pressure helps to understand how the liquids that are part of living beings are related.
Concept development
This concept was not known before the second half of the 18th century , when a physicist of French origin began to investigate it. A revealing experiment consisted of using a membrane from an animal organ and placing water on one side and alcohol on the opposite; To the scientist's surprise, the water passed through the fabric without problems, unlike the other compound, which remained on its side.
But it was only almost a century later that osmosis was discovered as a property of semipermeable membranes, when it was noted that when trying to cross it with two different solutions, the one with the smallest concentration of solute was always the one that managed to pass through to the other side. It was also observed that it had the ability to put pressure , now called osmotic, on the tissue.
Osmotic pressure measurement
A tool that also dates back to the mid -1800s and is called an osmometer is used to measure osmotic pressure. It is worth mentioning that this phenomenon plays a primary role in living organisms and can be observed directly at the cellular level, in processes of absorption and retention of different substances. After its study in a wide variety of non-volatile solute solutions, the following points were established:
- As long as the pressure does not suffer any alteration, the osmotic pressure remains in direct proportion to that of the solute concentration.
- For any particular solution, its osmotic pressure will have a direct proportion to the temperature .
- If two concentrations that have the same number of moles are taken and subjected to a particular temperature, they will have an equivalent osmotic pressure. It should be noted that molarity is the value that identifies the mass percentage of the solute found in each part of the solution.
The unit used to represent osmotic pressure is the same as for any other: the Pascal , abbreviated as Pa . However, the unit Atmosphere can also be used, the abbreviation of which is atm .