The law of gaseous volumes, also known as Gay-Lussac's law, states that the ratio between the volumes of gaseous reactants and products can be expressed in simple whole numbers
. This law was formulated by Joseph-Louis Gay-Lussac in 1808 and published in 1809. For example, in the reaction between hydrogen and chlorine to form hydrogen chloride, the ratio of volumes of hydrogen, chlorine, and hydrogen chloride is 1:1:2 (a simple ratio)
. Gay-Lussac's law can also refer to the proportionality of the volume of a gas to its absolute temperature at constant pressure, which is usually known as Charles's Law
