What is osmotic pressure and how it works

Answer 1

Osmotic Pressure: Osmotic pressure is a fundamental concept in chemistry and biology that describes the pressure exerted by a solvent when it flows through a semipermeable membrane to equalize the concentration of solute on both sides of the membrane. This process is known as osmosis.

How It Works:

1. Semipermeable Membrane:
2. Imagine a semipermeable membrane that allows the passage of solvent molecules (usually water) but restricts the passage of solute molecules (dissolved particles).
3. Unequal Solute Concentrations:
4. If there are unequal concentrations of solute on either side of the membrane, the solvent (with fewer solutes) will move through the membrane to dilute the more concentrated solution.
5. Equalizing Concentrations:
6. The solvent continues to move until the concentration of solute is equal on both sides of the membrane. This movement of solvent is driven by the desire to minimize the free energy of the system.
7. Osmotic Pressure Buildup:
8. As the solvent moves into the more concentrated solution, it exerts pressure on the membrane. This pressure is the osmotic pressure.

Examples:

1. Red Blood Cells: In biology, red blood cells have a semipermeable membrane. If they are placed in a solution with a higher solute concentration than inside the cells, water moves out of the cells, leading to cell shrinkage. Conversely, if the external solution has a lower solute concentration, water moves into the cells, causing them to swell.
2. Reverse Osmosis: In reverse osmosis, pressure is applied to a more concentrated solution to force the solvent through a semipermeable membrane, leaving the solutes behind. This process is used in water purification.

In summary, osmotic pressure is the force exerted by solvent molecules as they move through a semipermeable membrane to equalize solute concentrations, driven by the tendency to achieve equilibrium.

Answer 2

Osmotic pressure is the minimum amount of pressure needed to stop the flow of solvent molecules through a semipermeable membrane. Osmotic pressure is an example of a colligative property and is dependent on the concentration of solute molecules in the solution. This means that the solvent will move towards a greater concentration of solute molecules, helping to equalize the concentration on either side of the semipermeable membrane.

You can calculate osmotic pressure using this equation: π = iMRT in which...

π = Osmotic pressure

i = van Hoff's factor

M = molar concentration of the solution (mol/L)

R = Ideal gas constant (0.08206 L atm mol^-1 K^-1)

T = Temperature in Kelvin (K)

Hope this helps!