Gay-Lussac's law



Gay-Lussac's law is one of two laws named after the French chemist gases and are known by the same name.

Law of combining volumes

Gay-Lussac's law, known as the law of combining volumes, states that:

The ratio between the combining volumes of gases and the product, if gaseous, can be expressed in small whole numbers

Gay-Lussac discovered this law in 1809. This played a major role in the development of modern Avogadro's hypothesis.

Other law

The other law, discovered in 1802, states that:

The pressure of a fixed amount of gas at fixed volume is directly proportional to its temperature in kelvins.

It is expressed mathematically as:

{P}\propto{T}

or

\frac{P}{T}=k

where:

P is the pressure of the gas.
T is the temperature of the gas (measured in kelvins).
k is a constant.

This law holds true because temperature is a measure of the average kinetic energy of a substance; as the kinetic energy of a gas increases, its particles collide with the container walls more rapidly, thereby exerting increased pressure.

Simply put, if you increase the temperature you increase the pressure.

For comparing the same substance under two different sets of conditions, the law can be written as:

\frac{P_1}{T_1}=\frac{P_2}{T_2} \qquad \mathrm{or} \qquad {P_1}{T_2}={P_2}{T_1}

ideal gas law.

References

  • Castka, Joseph F.; Metcalfe, H. Clark; Davis, Raymond E.; Williams, John E. (2002). Modern Chemistry. Holt, Rinehart and Winston. ISBN 0-03-056537-5. 
  • Guch, Ian (2003). The Complete Idiot's Guide to Chemistry. Alpha, Penguin Group Inc.. ISBN 1-59257-101-8. 
  • Mascetta, Joseph A. (1998). How to Prepare for the SAT II Chemistry. Barron's. ISBN 0-7641-0331-8. 
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Gay-Lussac's_law". A list of authors is available in Wikipedia.