Amedeo Avogadro Amedeo Avogadro Amedeo Carlo Avogadro, () Count of Quaregna and Cerreto (9 August 17769 July 1856), was an Italian scientist, most noted for his contribution to molecular theory now known as Avogadro's law, which states that equal volumes of gases under the same conditions of temperature and pressure will contain equal numbers of molecules. In tribute to him, the number of elementary entities (atoms, molecules, ions or other particles) in 1 mole of a substance, , is known as the Avogadro constant, one of the seven SI base units and represented by "N". Lorenzo Romano Amedeo Carlo Avogadro was born
Humidity nitrogen (M ≈ 28) or a molecule of oxygen (M ≈ 32). About 78% of the molecules in dry air are nitrogen (N). Another 21% of the molecules in dry air are oxygen (O). The final 1% of dry air is a mixture of other gases. For any gas, at a given temperature and pressure, the number of molecules present in a particular volume is constant – see ideal gas law. So when water molecules (vapor) are introduced into that volume of dry air, the number of air molecules in the volume must decrease by the same number, if the