Partial Pressure Converter
Instantly convert partial pressure with our free converter. See conversion tables, formulas, and step-by-step explanations.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator
Partial Pressure Converter
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Formula: P_i = x_i x P_total (Dalton Law)
Worked example โ N2: 0.7808 atm | O2: 0.2095 atm | Ar: 0.0093 atm
Formula
P_i = x_i x P_total (Dalton Law)
The partial pressure of each gas component equals its mole fraction (x_i) multiplied by the total pressure of the mixture. Mole fractions must sum to 1.0 for a complete mixture description. Convert between pressure units using standard conversion factors.
Worked Examples
Example 1: Air Composition at Sea Level
Problem:Calculate partial pressures of N2 and O2 in air at 1 atm total pressure.
Solution:P(N2) = 0.7808 x 1 atm = 0.7808 atm = 593.4 mmHg P(O2) = 0.2095 x 1 atm = 0.2095 atm = 159.2 mmHg P(Ar) = 0.0093 x 1 atm = 0.0093 atm = 7.07 mmHg
Result:N2: 0.7808 atm | O2: 0.2095 atm | Ar: 0.0093 atm
Example 2: Diving Gas Mix at Depth
Problem:A diver breathes Nitrox (32% O2, 68% N2) at 2.5 atm (15m depth). Find partial pressures.
Solution:P(O2) = 0.32 x 2.5 = 0.80 atm P(N2) = 0.68 x 2.5 = 1.70 atm Note: O2 toxicity threshold is ~1.6 atm
Result:O2: 0.80 atm | N2: 1.70 atm
Frequently Asked Questions
What is Dalton Law of Partial Pressures?
Dalton Law states that the total pressure of a gas mixture equals the sum of the partial pressures of each individual gas component. The partial pressure of each gas is the pressure it would exert if it alone occupied the entire volume at the same temperature. Mathematically, P_total = P_1 + P_2 + P_3 + ... for all gas components. This law holds rigorously for ideal gases and is a good approximation for real gases at moderate pressures and temperatures.
How do you calculate the partial pressure of a gas in a mixture?
The partial pressure of a gas equals its mole fraction multiplied by the total pressure of the mixture: P_i = x_i times P_total. The mole fraction is the number of moles of that gas divided by the total moles of all gases. For example, in dry air at 1 atm, nitrogen has a mole fraction of 0.7808, so its partial pressure is 0.7808 times 1 = 0.7808 atm, or about 593.4 mmHg. This relationship follows directly from the ideal gas law applied to each component.
Why are partial pressures important in chemistry and biology?
Partial pressures are critical in many areas of science. In respiratory physiology, the partial pressure of oxygen (pO2) determines how effectively oxygen binds to hemoglobin in the blood. In chemical engineering, partial pressures are used to calculate chemical equilibrium constants (Kp) for gas-phase reactions. In diving medicine, nitrogen partial pressure determines decompression requirements. In environmental science, the partial pressure of CO2 in the atmosphere drives climate change models and ocean acidification calculations.
Do mole fractions always need to sum to exactly 1?
Yes, for a complete description of a gas mixture, the mole fractions of all components must sum to exactly 1.0 (or 100%). If the sum is less than 1, it means there are additional gas components not accounted for. If the sum exceeds 1, there is an error in the input values. In practice, minor components like noble gases or trace pollutants are sometimes omitted for simplicity, but the partial pressures of the listed gases will still be correctly calculated as long as their individual mole fractions are accurate.
References
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