Avogadro's Law

Avogadro's law is an experimental gas law relating the volume of a gas to the amount of substance of gas present. A modern statement is: equal volumes of all gases, at the same temperature and pressure, have the same number of molecules.

The law is named after Amedeo Avogadro who, in 1811, hypothesized that two given samples of an ideal gas, of the same volume and at the same temperature and pressure, contain the same number of molecules.

The law is named after Amedeo Avogadro who, in 1811, hypothesized that two given samples of an ideal gas, of the same volume and at the same temperature and pressure, contain the same number of molecules.

The hypothesis was first published by Amedeo Avogadro in 1811, and it reconciled Dalton atomic theory with the incompatible idea of Joseph Louis Gay-Lussac that some gases were composite of different fundamental substances (molecules) in integer proportions.