1. What Is Osmotic Pressure?

Osmotic pressure (Π) is the minimum pressure needed to prevent the inward flow of a solution's pure solvent across a semipermeable membrane. It's a colligative property, meaning it depends on the number of solute particles in solution.

2. How Does the Calculator Work?

The calculator uses the osmotic pressure equation:

Where:

• \( \Pi \) — Osmotic pressure (atm)
• \( i \) — Van't Hoff factor (dimensionless)
• \( M \) — Molarity (mol/L)
• \( R \) — Gas constant (0.08206 L·atm/(K·mol))
• \( T \) — Temperature (K)

Explanation: The equation shows that osmotic pressure is directly proportional to the molar concentration of solute particles and the absolute temperature.

3. Importance of Osmotic Pressure

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, higher for electrolytes), molarity in mol/L, 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 solute dissociates into in solution (e.g., 1 for glucose, ~2 for NaCl, ~3 for CaCl₂).

Q2: Why must temperature be in Kelvin?
A: The gas constant R is defined using Kelvin, and absolute temperature is required for thermodynamic equations.

Q3: What are typical osmotic pressure values?
A: Physiological solutions are ~7.6 atm, seawater ~30 atm, and concentrated solutions can exceed 100 atm.

Q4: Does this work for non-ideal solutions?
A: For highly concentrated solutions, activity coefficients should be used instead of molarity.

Q5: How is this related to osmosis?
A: Osmotic pressure quantifies the driving force for osmosis - the higher Π, the stronger the solvent flow.