Dalton's Law of Partial Pressures Calculator
Calculates the total pressure of a gas mixture from the sum of its individual partial pressures.
Formula first
Overview
Dalton's Law of Partial Pressures states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases. Each gas in the mixture exerts a partial pressure, which is the pressure it would exert if it alone occupied the entire volume. This law is fundamental to understanding gas behavior in various biological and chemical systems, particularly in respiratory physiology.
Symbols
Variables
P_1 = Partial Pressure of Gas 1, P_2 = Partial Pressure of Gas 2, P_3 = Partial Pressure of Gas 3, P_{\text{total}} = Total Pressure
Apply it well
When To Use
When to use: Apply this law when dealing with gas mixtures, such as atmospheric air, or gases within the lungs, to determine the overall pressure or the contribution of individual gases. It's crucial for understanding how gases move across membranes based on pressure gradients.
Why it matters: This law is vital in biology for understanding respiratory physiology, including how oxygen and carbon dioxide are exchanged in the lungs and tissues. It also explains phenomena like decompression sickness in diving and the effects of altitude on gas exchange, making it critical for medical and environmental sciences.
Avoid these traps
Common Mistakes
- Mixing pressure units (e.g., kPa and mmHg) without conversion.
- Assuming the law applies to reacting gases.
- Forgetting to account for all gases present in a mixture.
One free problem
Practice Problem
A gas mixture contains three non-reacting gases with partial pressures of 21.2 kPa, 79.8 kPa, and 0.1 kPa respectively. What is the total pressure of this gas mixture?
Solve for:
Hint: Sum the individual partial pressures.
The full worked solution stays in the interactive walkthrough.
References
Sources
- Atkins' Physical Chemistry
- Wikipedia: Dalton's law
- NIST CODATA
- Vander's Human Physiology: The Mechanisms of Body Function, 16th ed. (Eric P. Widmaier, Hershel Raff, Kevin T. Strang)
- Atkins' Physical Chemistry, 11th ed. (Peter Atkins, Julio de Paula, James Keeler)
- Atkins, P. W., & de Paula, J. (2014). Atkins' Physical Chemistry (10th ed.). Oxford University Press.
- Bird, R. B., Stewart, W. E., & Lightfoot, E. N. (2007). Transport Phenomena (2nd ed.). John Wiley & Sons.
- Callen, H. B. (1985). Thermodynamics and an Introduction to Thermostatistics (2nd ed.). John Wiley & Sons.