## Quick Reference

The volume of a fixed mass of gas at constant pressure expands by a constant fraction of its volume at 0°C for each Celsius degree or kelvin its temperature is raised. For any ideal gas the fraction is approximately 1/273. This can be expressed by the equation *V* = *V*_{0} (1+*t*/273), where *V*_{0} is the volume at 0°C and *V* is its volume at *t*°C. This is equivalent to the statement that the volume of a fixed mass of gas at constant pressure is proportional to its thermodynamic temperature, *V* = *kT*, where *k* is a constant. The law resulted from experiments begun around 1787 by Jacques Charles but was properly established only by the more accurate results published in 1802 by Joseph Gay-Lussac. Thus the law is also known as Gay-Lussac's law. An equation similar to that given above applies to pressures for ideal gases:*p* = *p*_{0} (1+*t*/273), a relationship known as Charles' law of pressures. See also gas laws.

*V* = *V*_{0} (1+*t*/273)

*p* = *p*_{0} (1+*t*/273)

**From:**
Charles' law
in
A Dictionary of Chemistry »

*Subjects:*
Chemistry — Physics.

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