1. What is Osmotic Pressure?

Definition: Osmotic pressure is the minimum pressure needed to prevent the inward flow of a solution's pure solvent across a semipermeable membrane.

Purpose: This calculator helps determine the osmotic pressure of a solution using the van't Hoff equation.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \pi \) — Osmotic pressure (Pascals)
• \( i \) — Van't Hoff factor (dimensionless)
• \( c \) — Molar concentration (mol/m³)
• \( R \) — Gas constant (8.314 J/mol·K)
• \( T \) — Temperature (Kelvin)

Explanation: The formula calculates the pressure required to stop osmosis based on solution properties and temperature.

3. Importance of Osmotic Pressure

Details: Understanding osmotic pressure is crucial in biological systems, water purification, and industrial processes like reverse osmosis.

4. Using the Calculator

Tips: Enter the van't Hoff factor (default 1), molar concentration, gas constant (default 8.314), and temperature in Kelvin (default 298). All values must be > 0.

5. Frequently Asked Questions (FAQ)

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

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

Q3: What units should concentration be in?
A: The calculator uses mol/m³. To convert from mol/L, multiply by 1000.

Q4: Can I use different units for pressure?
A: The result is in Pascals. 1 atm = 101325 Pa, 1 bar = 100000 Pa.

Q5: What's a typical osmotic pressure value?
A: For 0.1 M NaCl at 25°C (i=2, c=100 mol/m³, T=298K), π ≈ 495 kPa.