Osmotic Pressure

Rucete ✏ Chemistry In a Nutshell

1. What is Osmosis?

• Osmosis is the movement of solvent molecules through a semi-permeable membrane.
• Solvent flows from a low solute concentration to a high solute concentration to balance concentrations.

2. Osmotic Pressure ($\mathrm{\Pi }$)

• The pressure required to stop osmosis from occurring.

• Formula:

  $$\mathrm{\Pi }=iMRT$$
  
  • $\mathrm{\Pi }$ = Osmotic pressure (atm)
  • $i$ = Van’t Hoff factor (number of particles the solute dissociates into)
  • $M$ = Molarity (mol/L)
  • $R$ = Gas constant (0.0821 L·atm/mol·K)
  • $T$ = Temperature (K)

• Higher solute concentration → Higher osmotic pressure.

3. Importance of Osmotic Pressure

• Biological Systems: Maintains cell water balance (isotonic, hypertonic, hypotonic solutions).
• Food Preservation: High salt/sugar solutions prevent bacterial growth.
• Medical Applications: Used in IV solutions and dialysis.

Osmotic Pressure In a nutshell

• Osmosis moves water from low to high solute concentration.
• Higher solute concentration = Higher osmotic pressure.