Pressão Parcial (Dalton)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
P_i = x_i·P
About this calculator
This partial pressure calculator applies Dalton's Law for ideal gas mixtures. It calculates the partial pressure of a gas component (P_i) from its mole fraction (x_i) and the total pressure of the system (P_total). The formula is P_i = x_i · P_total, where x_i is the ratio of moles of the component to total moles. This tool is useful for chemistry and physics students, engineers, and professionals working with gases in industrial or laboratory settings.
To use the calculator, enter the total pressure (in atm, bar, kPa, or mmHg) and the mole fraction of the gas of interest (value between 0 and 1). The result is the partial pressure of that gas. Dalton's Law assumes non-interacting gases behaving ideally, valid at low pressures and moderate temperatures. Deviations may occur at high pressures or low temperatures.
Use cases include calculating oxygen partial pressure in scuba diving to avoid toxicity, determining vapor pressure in distillation systems, and analyzing gases in chemical reactions. The calculator can also verify gas mixture composition from experimental data.
Frequently asked questions
What is partial pressure?
Partial pressure is the pressure that a gas would exert if it alone occupied the total volume of the mixture at the same temperature. The sum of partial pressures of all components equals total pressure.
Is Dalton's Law valid for real gases?
Dalton's Law is an approximation for ideal gases. For real gases, especially at high pressures or low temperatures, deviations may occur due to intermolecular interactions.
How do I convert pressure units?
The calculator accepts atm, bar, kPa, and mmHg. Use: 1 atm = 1.01325 bar = 101.325 kPa = 760 mmHg.
What is mole fraction?
Mole fraction (x_i) is the ratio of moles of a component to total moles in the mixture. Its value is always between 0 and 1.
Can I use this calculator for liquids?
No. Dalton's Law applies only to gas mixtures. For liquids, use Raoult's Law for vapor partial pressures.