Stanislao Cannizzaro in Italy. He is best known for his contribution to the then-existing debate over atoms, molecules, and atomic weights. He championed Amedeo Avogadro's notion that equal volumes of gas at the same pressure and temperature held equal numbers of molecules or atoms, and the notion that equal volumes of gas could be used to calculate atomic weights. In so doing, Cannizzaro provided a new understanding of chemistry. Stanislao Cannizzaro Stanislao Cannizzaro FRS (13 July 1826 – 10 May 1910) was an Italian chemist. He is remembered today largely for the Cannizzaro reaction and for his influential role in the atomic-weight
Avogadro's law 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. As an example, equal volumes of molecular hydrogen and nitrogen contain the same number of molecules when they are at the same temperature and pressure, and observe ideal gas behavior. In practice, real gases show small deviations from the ideal behavior and the law holds only approximately, but is still a useful approximation for scientists. The law can be written as: or where This law describes how, under the same