Osmotic Pressure Calculator

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Calculate the pressure required to stop osmosis in a solution using the van't Hoff equation.

Presets

Solution Parameters

Van't Hoff Factor (i)

Molarity (M)

Temperature (T)

Results

Output Unit

Osmotic Pressure (π)7.340atm

Biological Status

Isotonic

Same as human blood

Pressure vs. Concentration

About this calculator

Overview

Osmotic pressure is a colligative property, meaning it depends on the number of solute particles rather than their chemical identity. It is the minimum pressure that needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane. This concept is vital in medicine (IV fluids), biology (cell stability), and engineering (reverse osmosis).

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Pro Tips

i is the number of particles the solute dissociates into (e.g., NaCl dissociates into 2 ions, i=2).
M is molarity in mol/L.
T is absolute temperature in Kelvin (T_K = T_C + 273.15).
R is the ideal gas constant (0.08206 L·atm/(mol·K)).

Fun Facts

"Osmotic pressure allows trees as tall as Giant Sequoias to lift water hundreds of feet to their topmost leaves."
"A red blood cell placed in pure water will swell and burst (hemolysis) due to osmotic pressure."
"Reverse osmosis (RO) filters work by applying pressure higher than the osmotic pressure to force pure water out of salty or dirty water."
"Traditional food preservation methods like salting meat or sugaring fruit work by creating high osmotic pressure that dehydrates and kills microbes."

Formula: \pi = i \cdot M \cdot R \cdot T