Dalton's law
Dalton's law (also called 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.[1] This empirical law was
observed by John Dalton in 1801 and
published in 1802.[2] Dalton's law is
related to the ideal gas laws.
An illustration of Dalton's law using the gases of air at sea level.
Formula
Mathematically, the pressure of a mixture of non-reactive gases can be defined as the summation:
where p1 , p2 , ..., pn represent the partial pressures of each component.[1]
where xi is the mole fraction of the ith component in the total mixture of n components .
Volume-based concentration
The relationship below provides a way to determine the volume-based concentration of any individual
gaseous component
where ci is the concentration of component i.
Dalton's law is not strictly followed by real gases, with the deviation increasing with pressure. Under such
conditions the volume occupied by the molecules becomes significant compared to the free space between
them. In particular, the short average distances between molecules increases intermolecular forces between
gas molecules enough to substantially change the pressure exerted by them, an effect not included in the
ideal gas model.
See also
Amagat's law – Gas law describing volume of a gas mixture
Boyle's law – Relationship between pressure and volume in a gas at constant temperature
Combined gas law – Combination of Charles', Boyle's and Gay-Lussac's gas laws
Gay-Lussac's law – Relationship between pressure and temperature of a gas at constant
volume
Henry's law – Gas law regarding proportionality of dissolved gas
Mole (unit) – SI unit of amount of substance
Partial pressure – Pressure of a component gas in a mixture
Raoult's law – Law of thermodynamics for vapour pressure of a mixture
Vapor pressure – Pressure exerted by a vapor in thermodynamic equilibrium
References
1. Silberberg, Martin S. (2009). Chemistry: the molecular nature of matter and change (https://ar
chive.org/details/chemistrymolecul00silb_143) (5th ed.). Boston: McGraw-Hill. p. 206 (https://
archive.org/details/chemistrymolecul00silb_143/page/n234). ISBN 9780073048598.
2. J. Dalton (1802), "Essay IV. On the expansion of elastic fluids by heat," (https://books.googl
e.com/books?id=3qdJAAAAYAAJ&pg=PA595) Memoirs of the Literary and Philosophical
Society of Manchester, vol. 5, pt. 2, pages 595–602; see page 600.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Dalton%27s_law&oldid=1145039316"