O

Osmosis

Osmotic pressure π = MRT | M = molarity, R = 8.314, T = Kelvin
Quick Reference
Formula / NotationOsmotic pressure π = MRT | M = molarity, R = 8.314, T = Kelvin
Also Known AsOsmotic flow, Membrane diffusion

What is Osmosis?

The movement of solvent molecules through a semi-permeable membrane from a region of lower solute concentration to higher solute concentration. Osmotic pressure is the pressure needed to prevent this flow. Osmosis is vital in biological systems for cell volume regulation.

Formula & Notation

Osmotic pressure π = MRT | M = molarity, R = 8.314, T = Kelvin

Other Names / Synonyms: Osmotic flow, Membrane diffusion

Properties & Characteristics

Solvent moves from low solute concentration to high solute concentration through semipermeable membrane. Osmotic pressure π = iMRT (i = van't Hoff factor for electrolytes). Blood osmolarity ≈ 290 mOsm/kg. Isotonic saline: 0.9% NaCl (308 mOsm/L). Hypertonic: higher osmolarity than cells (cells shrink). Hypotonic: lower osmolarity (cells swell and burst — hemolysis). Reverse osmosis: applying pressure > π forces water through membrane.

Uses & Applications

Reverse osmosis water purification (removes salts, pollutants — used in desalination). IV fluid formulation (must be isotonic for blood compatibility). Dialysis kidney function replacement. Food preservation (high sugar or salt creates hypertonic environment, inhibiting microorganism growth). Plant water uptake from soil. Measurement of molar mass of polymers and proteins.

Safety Information

Hypertonic IV solutions cause hemolysis of red blood cells — must precisely control osmolarity of intravenous fluids. Reverse osmosis membranes require regular sanitization to prevent bacterial biofilm growth. Osmotic pressure in sealed containers with hygroscopic materials can build up causing container rupture.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Osmosis
Formula Osmotic pressure π = MRT | M = molarity, R = 8.314, T = Kelvin
Synonyms Osmotic flow, Membrane diffusion

Frequently Asked Questions

The movement of solvent molecules through a semi-permeable membrane from a region of lower solute concentration to higher solute concentration. Osmotic pressure is the pressure needed to prevent this flow. Osmosis is vital in biological systems for cell volume regulation.

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