Chemistry

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Raoult's Law Calculator.

Calculate ideal binary-solution partial and total vapor pressure from explicit mole fractions and pure-component pressures.

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01

Set your values

Results update as you type.

Partial pressure 1: 8 kPa

Partial pressure 1

8.000000kPa
Partial pressure 2: 6 kPa

Partial pressure 2

6.000000kPa
Total pressure: 14 kPa

Total pressure

14.000000kPa

How to Use

Every model convention and source-dependent parameter is visible. Results update automatically after each edit.

Use Cases

Predict vapor pressure of ideal mixtures

Useful for chemistry students and researchers to quickly estimate the vapor pressure of a binary ideal solution, aiding in distillation and evaporation studies.

Example: For a mixture with mole fractions 0.4 and 0.6 and pure pressures 100 and 200 mmHg, total pressure is 160 mmHg.

Check consistency of mole fractions

Helps verify that the mole fractions sum to 1, which is essential for accurate Raoult's Law calculations.

Example: If you input 0.5 and 0.5, the calculator confirms the sum is 1.

Frequently Asked Questions

What is Raoult's Law and how does this calculator use it?
Raoult's Law states that the partial vapor pressure of a component in an ideal solution equals its mole fraction times its pure-component vapor pressure. This calculator applies that to both components and sums them to give the total vapor pressure.
What inputs do I need to use this calculator?
You need the mole fraction of each component (which should sum to 1) and the pure-component vapor pressures at the given temperature. The calculator then computes the partial pressures and the total vapor pressure.
Can I use this calculator for non-ideal solutions?
No, this calculator is specifically for ideal binary solutions. Real solutions may deviate due to intermolecular interactions, so results may not match experimental values.

Tips & Common Mistakes

Tips

  • Ensure mole fractions sum to 1; otherwise, the partial pressures will not be accurate.
  • Use consistent units for pure-component pressures (e.g., both in atm or both in mmHg).
  • This calculator assumes ideal behavior; for non-ideal solutions, consider using activity coefficients.
  • Double-check your pure-component vapor pressures at the specific temperature of interest.

Common Mistakes to Avoid

  • Entering mole fractions that do not sum to 1, leading to incorrect partial pressures.
  • Using different pressure units for the two components without conversion.
  • Assuming the calculator accounts for temperature changes; it only uses the given pure pressures.

Last updated: August 13, 2026