Dalton's Law of Partial Pressures Calculator
Use Dalton's Law two ways. Enter the partial pressures of each gas to get the total pressure and mole fractions, or enter a total pressure with mole fractions to get each partial pressure. Pressures can be in any consistent unit.
How to use the Dalton's Law calculator
- Choose a mode: partial pressures, or total pressure with mole fractions.
- Enter the values, one per component, in any consistent pressure unit.
- Read the total pressure, partial pressures and mole fractions.
Examples
Sum partial pressures
Partial pressures = 2, 3, 5
Total = 10, mole fractions = 0.2, 0.3, 0.5
Split by mole fraction
Total = 10, mole fractions = 0.2, 0.8
Partial pressures = 2, 8
Frequently asked questions
What is Dalton's Law of partial pressures?
Dalton's Law states that the total pressure of a mixture of non-reacting gases equals the sum of the partial pressures of each gas.
What is a partial pressure?
A partial pressure is the pressure a single gas in a mixture would exert if it alone occupied the whole volume at the same temperature.
How are mole fractions related to partial pressures?
Each gas's mole fraction equals its partial pressure divided by the total pressure, so the mole fractions of a mixture always sum to 1.
What pressure units can I use?
Any consistent unit works, such as atm, kPa, bar or mmHg, as long as every value uses the same unit.
Why must the mole fractions sum to 1?
Mole fractions describe shares of the whole mixture, so they must add up to 1. The calculator checks this within a small tolerance.
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