Charles's law
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Charles's law is one of the gas laws. It states that:
- At constant pressure, the volume of a given mass of an ideal gas increases or decreases by the same factor as its temperature (in kelvins) increases or decreases.
The law was first published by Joseph Louis Gay-Lussac in 1802, but he referenced unpublished work by Jacques Charles from around 1787. This reference has led to the law being attributed to Charles. The relationship had been anticipated by the work of Guillaume Amontons in 1702.
The formula for the law is:
where:
- V is the volume of the gas
- T is the temperature of the gas (measured in kelvins)
- k is a constant.
To maintain the constant, k, during heating of a gas at fixed pressure, the volume must increase. Conversely, cooling the gas decreases the volume. The exact value of the constant need not be known to make use of the law in comparison between two volumes of gas at equal pressure:
.
In simpler form, as the temperature increases the volume of the gas increases.
Charles' Law, Gay-Lussac's Law, and Boyle's Law form the combined gas law. The three gas laws in combination with Avogadro's Law can be generalized by the ideal gas law.
