Osmotic Pressure Calculator

Osmotic Pressure Calculator

Estimate osmotic pressure using van't Hoff's law (ideal solutions).

2026-05-06T10:07:27.248Z
mol/L
K
i

Osmotic Pressure (Π)

0.0000 atm

Π = i M R T

What is Osmotic Pressure?

Osmotic pressure is the minimum pressure required to stop solvent flow through a semipermeable membrane into a solution. For ideal dilute solutions, van't Hoff's law approximates Π ≈ iMRT.

How to use

Provide molarity (mol/L), temperature (K) and the van't Hoff factor i. The result is in atm for the chosen units.

Example

For 0.1 M NaCl (i≈2) at 298.15 K: Π ≈ 2 × 0.1 × 0.08206 × 298.15 ≈ 4.89 atm.

FAQs

Q: Are non-ideal solutions covered? A: No — this is for ideal/dilute approximations. Q: Units? A: Use mol/L, K, and R=0.08206 L·atm/(mol·K).

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