Osmotic Pressure 

As to define osmotic pressure, we can say that osmotic pressure is the minimum pressure that is needed to stop a pure solvent from flowing inward through a semipermeable barrier. In other words, osmotic pressure can also be called a measurement of the proclivity of a solution in order to use osmosis to absorb a pure solvent. 

Osmosis happens when two different solutions with different quantities of solute have a permeable membrane between them, causing a separation. Solvent molecules flow over the membrane preferentially from a solution with low concentration to an elevating solute concentration solution. The transfer of solvent molecules goes on till the equilibrium is established.

When a semipermeable membrane separates a solution from pure water, osmotic pressure is the pressure that has to be applied to the solution side to cease fluid movement.

Jacobus Henricus van ‘t Hoff, a Dutch-born chemist, demonstrated in 1886: when a dilute solute whose partial vapour pressure follows Henry’s law when above the solution, then osmotic pressure fluctuates with temperature and concentration of a gas with a similar volume.

This relationship gives out the formulae for calculating the solute’s molecular weights in dilute solutions depending on the boiling, freezing, and vapour pressure of the solvent. 

It is calculated using the following formula:

π = iCRT

Where,

π = osmotic pressure

i = van’t Hoff index

C = molar concentration of the solute 

R = ideal gas constant

T = temperature in Kelvin

Solvent molecules pass over a semipermeable membrane from one region to another where the concentration of the solute is low to a region where the concentration of the solute is high, eventually establishing equilibrium on both sides and resulting in the same concentration on both sides, is referred to as osmosis. Diffusion is a specific case of osmosis.

It is the mechanism by which a solvent flows in the opposite direction of natural osmosis over a semipermeable membrane. The water filtration method known as reverse osmosis removes ions, undesirable compounds, and bigger particles from drinking water.

Systems Regulated by Osmotic Pressure: 

A semipermeable membrane is placed around the tablet, particle, or drug solution in osmotic pressure controlled systems, allowing water to enter the tablet and drug solution to be pumped out through the small delivery hole in the tablet core. There are two types of osmotic pressure-regulated systems described in the literature. The drug is held in a flexible bag that is surrounded by an osmotic core in type 1, whereas the drug is held in a flexible bag that is surrounded by an osmotic core in type 2. It is feasible to design an osmotic system to distribute a variety of drugs at a predetermined rate by optimising the formulation and processing variables.

Osmosis is a process in which fluid flows from a lower concentration to a higher concentration across a semipermeable membrane that allows only liquid to pass through. The medicine is coated with a semipermeable membrane, and a laser beam is used to create a hole in one end of the tablet. The drug solution is pumped out of the aperture and released into the stomach environment as the gastric fluid seeps through the membrane, solubilises the drug, and increases the internal pressure, causing the medication solution to be pumped out of the aperture and released into the gastric environment. If there is an excess of medicine inside the pill, the delivery rate remains constant. When the concentration falls below the saturation point, however, it drops to zero.

Osmosis and Osmotic Pressure: 

Osmosis is the diffusion of water or other solvents through a semipermeable barrier (one that prevents the passage of dissolved compounds, such as solutes).

Wilhelm Pfeffer, a German plant physiologist, was the first to explore this vital biological process. Previously, less detailed studies of leaky membranes (e.g., animal bladders) and the transit of water and escape compounds in opposite directions across them had been done. Thomas Graham, a British physicist, created the term osmose in 1854. (now osmosis).

The osmotic pressure of a solution is intimately linked to various other features of the solution, known as colligative qualities. Solutes dissolving in a solution causes freezing point depression, boiling point elevation, and vapour pressure depression, among other effects. Rather than direct osmotic pressure measurements, vapour pressure depression of freezing point depression is frequently used to estimate osmolarity. The concentration required to witness these phenomena is referred to as osmolarity.

Because its vapour pressure is lower than that of the water, a solution placed in a sealed container with a source of clean water will gain water. The semipermeable membrane in this circumstance is the intervening air between the two surfaces, which is formally identical to osmosis. Because osmotic pressure and vapour pressure depression are essentially the same processes, they are perfect forecasters of each other.

Osmotic Pressure in Plants

A discrepancy in the quantities of solutes between solutions separated by a semipermeable barrier causes hydrostatic pressure. Water potential, or the tendency for water to move from one place to another, is reduced by osmotic pressure. It is therefore required in plant cells for turgidity and support.

Osmotic pressure can build up inside a cell when water enters through osmosis. A cell with a cell wall helps to keep the cell’s water balance in check. In many plants, osmotic pressure is the primary source of support. The turgor pressure forced against the cell wall by the osmotic entry of water into a hypotonic plant cell rises until it prevents more water from entering the cell. At this point, the plant cell is turgid.

Osmosis can be extremely destructive to organisms, particularly those without cell walls. 

The cells of a saltwater fish (whose cells are isotonic with seawater) will absorb extra water, lyse, and die if they are placed in freshwater.

The usage of table salt to kill slugs and snails is another example of a detrimental osmotic impact.

Example of Osmosis: 

Osmosis is the process through which water is absorbed from the earth. Water flows into the roots because the plant roots’ concentration is higher than that of soil. The passage of water inside the cells causes the fingers to become pruney when they are submerged for an extended period of time. Osmosis is a vital process in the lives of plants, animals, and humans. Water absorption from the intestines to the blood in animal cells is aided by osmosis.

Osmotic Solutions:

• Isotonic solution – The solute’s concentration is equal within and outside the cell.

• Hypotonic solution – The solute’s concentration inside the cell is higher than outside.

• Hypertonic solution – The solutes’ concentration outside the cell is higher than inside the cell.

Types of Osmosis:

1. Endosmosis – When a material is submerged in a hypotonic solution, the solvent molecules enter the cell, making it turgid or de-plasmolyzed. 

2. Exosmosis – When a material is placed in a hypertonic solution, the solvent molecules escape, the cell becomes flaccid or plasmolysed as a result. 

Controlling osmosis is one way the body keeps water. When the body is dehydrated, the brain tells the kidneys to concentrate urine so that more water can be retained. Antidiuretic hormone (ADH) is a hormone produced by the brain and transported to the kidneys via circulation. A network of tubes that runs through the kidneys is known as the collecting ducts. Water is generally impermeable to the collecting ducts; thus, if water is in the collecting duct, it is on its way to the bladder. ADH, on the other hand, causes water channels to open in the walls of the collecting ducts. Water that would otherwise become urine can now flow out of the collecting duct and back into the bloodstream.

Conclusion

Here we learned about osmotic pressure and the process of osmosis in detail. The article also looks into different examples of osmosis to help readers understand the process in a much more elaborate manner. Learn about the osmotic pressure in plants and other important topic relevant queries.