Name: Lowering in Freezing Point
Uploaded: 2019-07-19
Duration: 7 min 56 s
Description: Addition of a non-volatile solute to a solvent results in a decrease in the vapour pressure. This results in a decrease in the freezing point of the solution...

Question

Define Osmotic Pressure.

Accepted Answer

Osmotic pressure is the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. It is also defined as the measure of the tendency of a solution to take in pure solvent by osmosis. Potential osmotic pressure is the maximum osmotic pressure that could develop in a solution if it were separated from its pure solvent by a selectively permeable membrane. The phenomenon of osmosis arises from the propensity of a pure solvent to move through a semipermeable membrane and into its solution containing a solute to which the membrane is impermeable. This process is of vital importance in biology as the cell's membrane is semipermeable.

When a semipermeable membrane is placed between a solution and solvent, it is observed that solvent molecules enter the solution through the semipermeable membrane and the volume of the solution increases. The semipermeable membrane allows only solvent molecules to pass through it but prevents the passage of bigger molecules like solute. This phenomenon of the spontaneous flow of solvent molecules through a semipermeable membrane from a pure solvent to a solution or from a dilute to a concentrated solution is called osmosis. The flow of solvent molecules through the semipermeable membrane can be stopped if some extra pressure is applied from the solution side. This pressure that just stops the flow of solvent is called the osmotic pressure of the solution.

Dilute solution containing non-volatile solute exhibit some properties which depend only on the number of solute particles present and not on the type of solute present. These properties are called colligative properties.

There are four colligative properties that can be exhibited by a solution:

Osmotic pressure.

Boiling point elevation

Freezing point depression and

Relative lowering of vapour pressure.

Define Osmotic Pressure.

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