Partial Pressure Calculator
Combine mole fractions with total pressure to determine individual gas partial pressures using Dalton's law.
Gas 1
Fraction: 0.7
0.7 atm
Gas 2
Fraction: 0.3
0.3 atm
How to Use This Calculator
Enter total pressure
Provide the mixture pressure in atmospheres or convert other units to atm.
List component fractions
Enter mole fractions for each gas. Enable automatic normalization if you have approximate values.
Review partial pressures
Each component pressure equals its fraction multiplied by the total pressure.
Apply Dalton's law
Use results for gas blending, reactor feeds, or vapor-liquid equilibrium calculations.
Formula
Pi = yi * Ptotal
Pi is partial pressure, yi mole fraction of component i, Ptotal the sum of all partial pressures.
Example
For Ptotal = 2 atm with fractions 0.6, 0.3, 0.1: partial pressures are 1.2 atm, 0.6 atm, 0.2 atm respectively.
Full Description
Dalton's law of partial pressures assumes ideal gas behavior where individual gas pressures add linearly to the total pressure.
This tool streamlines calculations for lab mixtures, respiratory gas blends, or headspace analysis when composition data are known.
Frequently Asked Questions
What if fractions are given in percent?
Divide each percentage by 100 before entering or enable normalization to scale them automatically.
Can I use partial pressures to find mole fractions?
Yes. Divide each partial pressure by the total pressure to recover the mole fraction.
Does this work for liquids?
Dalton's law applies to gases. For solutions, use Raoult's law or Henry's law equivalents.
How accurate is the ideal assumption?
It is reasonable at low to moderate pressures. Strongly interacting gases may require fugacity corrections.
Can I export the results?
Copy the displayed values or adapt the code to integrate with your data pipeline.