Partial Pressure Calculator

Dalton's Law & Gas Mixtures

Calculate the partial pressure of each gas in a mixture using Dalton's Law. Enter the total pressure and the amount (mol) of each gas. Supports multiple pressure units and dynamic gas entry.

Examples

See how to use the Partial Pressure Calculator in real-world scenarios.

Simple Air Mixture

Basic

Calculate the partial pressures of O₂ and N₂ in air at 1 atm total pressure.

Total Pressure: 1

Pressure Unit: atm

Gas Name: O₂

Amount (mol): 0.21

Gas Name: N₂

Amount (mol): 0.78

Diving Gas Mix

Diving

A diver breathes a mix of 80% He and 20% O₂ at 2 atm. Find the partial pressures.

Total Pressure: 2

Pressure Unit: atm

Gas Name: He

Amount (mol): 0.8

Gas Name: O₂

Amount (mol): 0.2

Lab Gas Collection

Laboratory

A mixture contains 0.5 mol CO₂ and 0.5 mol H₂ at 1.5 atm. Calculate each partial pressure.

Total Pressure: 1.5

Pressure Unit: atm

Gas Name: CO₂

Amount (mol): 0.5

Gas Name: H₂

Amount (mol): 0.5

Atmospheric Gases

Atmospheric

Atmospheric air at 101.3 kPa: N₂ (78%), O₂ (21%), Ar (1%). Find partial pressures.

Total Pressure: 101.3

Pressure Unit: kPa

Gas Name: N₂

Amount (mol): 0.78

Gas Name: O₂

Amount (mol): 0.21

Gas Name: Ar

Amount (mol): 0.01

Other Titles
Understanding Partial Pressure Calculator: A Comprehensive Guide
Master Dalton's Law and gas mixtures with this tool.

What is Partial Pressure?

  • Definition of Partial Pressure
  • Dalton's Law of Partial Pressures
  • Importance in Chemistry
Partial pressure is the pressure that a single gas in a mixture would exert if it occupied the entire volume alone at the same temperature. Dalton's Law states that the total pressure of a gas mixture is the sum of the partial pressures of each component gas.
Dalton's Law Formula

Partial Pressure Examples

  • If air contains 21% O₂ and 78% N₂ at 1 atm, the partial pressure of O₂ is 0.21 atm.
  • In a diving tank with 80% He and 20% O₂ at 2 atm, the partial pressure of He is 1.6 atm.

Step-by-Step Guide to Using the Calculator

  • Inputting Gas Data
  • Selecting Pressure Units
  • Interpreting Results
To use the calculator, enter the total pressure and the amount (in moles) of each gas. Select the desired pressure unit. The calculator will compute the mole fraction and partial pressure for each gas.
How to Use the Tool

Usage Examples

  • Add O₂ and N₂ with their mol values, set total pressure, and view results.
  • Switch between atm, kPa, mmHg, and bar for unit conversion.

Real-World Applications of Partial Pressure

  • Breathing Gas Mixtures
  • Industrial Gas Blends
  • Atmospheric Science
Partial pressure calculations are essential in scuba diving, medical gas delivery, industrial gas production, and atmospheric studies. Understanding partial pressures helps ensure safety and accuracy in these fields.
Applications in Science and Industry

Application Examples

  • Diving tanks are filled based on required partial pressures of O₂ and He.
  • Atmospheric scientists analyze partial pressures to study weather patterns.

Common Misconceptions and Correct Methods

  • Mixing Up Units
  • Ignoring Mole Fractions
  • Incorrect Total Pressure Use
A common mistake is using inconsistent units or forgetting to use mole fractions. Always ensure all values are in the same unit and use the correct formula for partial pressure.
Avoiding Calculation Errors

Misconception Examples

  • Don't use kPa for total pressure and atm for partial pressure in the same calculation.
  • Always use the correct mole fraction for each gas.

Mathematical Derivation and Examples

  • Dalton's Law Equation
  • Mole Fraction Calculation
  • Worked Example
Dalton's Law: Pi = Xi × Ptotal, where Xi = ni / ntotal. Calculate ntotal by summing all moles, then find each Xi and P_i.
Sample Calculation

Mathematical Examples

  • Given 0.5 mol CO₂ and 0.5 mol H₂ at 1.5 atm, each has a partial pressure of 0.75 atm.
  • For 0.78 mol N₂, 0.21 mol O₂, and 0.01 mol Ar at 101.3 kPa, partial pressures are 79.014, 21.273, and 1.013 kPa respectively.