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Solution Osmotic Pressure & Molar Concentration

Estimate osmotic pressure from concentration, temperature, particle factor and osmotic coefficient, or derive concentration from mass and solution volume.

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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

At 300 K, a 0.1 mol/L solution with particle factor 1 and osmotic coefficient 1 has modeled osmotic pressure 2.494338785445972 bar.

π = particle factor × osmotic coefficient × concentration × R × T; concentration = mass / (molar mass × solution volume)

Worked example

Enter these known values and leave the other values blank.

Particles per dissolved formula unit
1
Osmotic coefficient Φ
1
Solute amount concentration
0.1 mol/ L
Solution temperature
26.85 °C
Modeled osmotic pressure
2494.3 hPa

Assumptions and limitations

  • The particle factor describes dissolved particles per formula unit. Use 1 for an undissociated molecular solute. An ideal fully dissociated 1:1 salt would use 2; actual solution behavior may differ.
  • The osmotic coefficient is positive and equals 1 in the ideal limit. Avoid counting the same nonideality twice in the particle factor and coefficient.
  • Temperature must exceed absolute zero. The equation uses kelvins, mol/L and R = 0.0831446261815324 L·bar/(mol·K); selectors convert display units.
  • Concentration, solute mass, molar mass and final solution volume must be positive. Use final solution volume, not solvent volume before dissolution.
  • This is a single-solute solution model with entered coefficients. It is not a dosage, fluid-treatment or membrane-system design recommendation.

Common questions

Why does mol/L differ from mol/m³ by a factor of 1,000?

A cubic meter contains 1,000 liters. Therefore 0.1 mol/L equals 100 mol/m³; the concentration selector applies the reciprocal-volume conversion.

References

Bookify requires positive absolute temperature, osmotic coefficient and osmotic pressure for this positive-concentration solution model. Mercury pressure columns use conventional density and standard gravity, with the exact international inch. Pounds-force per square inch use the exact international pound and inch with standard gravity, replacing the rounded captured factor. One technical atmosphere is exactly one kilogram-force per square centimeter under standard gravity. The US fluid ounce uses one 128th of the exact US liquid gallon, replacing the rounded captured reciprocal factor. The US customary cup uses one sixteenth of the exact US liquid gallon, replacing the rounded captured cup volume. Bookify replaces the captured rounded US gallon with the exact 3.785411784-liter definition. Prices per thousand US gallons use the same exact gallon as the volume inputs.

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