1. What is Osmotic Pressure?

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's a colligative property, meaning it depends on the molar concentration of the solute but not its identity.

2. How Does the Calculator Work?

The calculator uses the osmotic pressure equation:

Where:

• \( \Pi \) — Osmotic pressure (Pa)
• \( i \) — Van't Hoff factor (dimensionless)
• \( c \) — Molar concentration (mol/m³)
• \( R \) — Gas constant (8.314 J/mol K)
• \( T \) — Absolute temperature (K)

Explanation: The equation accounts for the number of particles the solute dissociates into (i), the concentration of the solution, and the temperature.

3. Importance of Osmotic Pressure Calculation

Details: Osmotic pressure is crucial in biological systems (like kidney function), industrial processes (reverse osmosis), and pharmaceutical applications (IV solutions).

4. Using the Calculator

Tips: Enter the Van't Hoff factor (1 for non-electrolytes, 2 for NaCl, etc.), molar concentration in mol/m³, and temperature in Kelvin. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the Van't Hoff factor?
A: It represents the number of particles a compound dissociates into in solution (e.g., 1 for glucose, 2 for NaCl, 3 for CaCl₂).

Q2: Why is temperature in Kelvin?
A: The gas constant R uses Kelvin in its units, and absolute temperature is required for thermodynamic calculations.

Q3: What are typical osmotic pressure values?
A: Physiological saline (0.9% NaCl) has about 7.6 atm (770 kPa), while seawater is about 27 atm (2.7 MPa).

Q4: How does this relate to reverse osmosis?
A: Reverse osmosis requires pressure greater than the osmotic pressure to force solvent through the membrane against the concentration gradient.

Q5: What are limitations of this calculation?
A: It assumes ideal behavior and doesn't account for ion pairing or other non-ideal effects in concentrated solutions.