floppie86 t1_itqeefz wrote on October 25, 2022 at 3:24 PM

Reply to comment by Felinomancy in TIL Amedeo Avogadro's contribution to chemistry, known as Avogadro's law, did not initially receive much attention when he published his paper in 1811. It was only a century later that his work was recognized, when the King of Italy attended a meeting commemorating the paper's 100th anniversary. by dustofoblivion123

Avogadro's number is not really a discovery. It's just a smart calculation trick. We often want to do calculations in chemistry using ratio's in numbers (such as in chemical equations, 2 molecules of this will react with one molecul of that and such). But measurements is done in masses using scales (you cant count molecules duh).

We've chosen to calculate in large numbers of molecules (containing 6.022*10^23 molecules in one such unit) for obvious reasons; molecules come in large numbers. This specific number is chosen because it is the ratio between the mass of a gram and the atomic mass unit (u, roughly the mass of a proton). This allows us to easily calculate moles from mass (in gram) using the weight of a molecule in u.

So one mole of carbon weighs 12 gram because one atom of carbon weighs 12 u. One u is 1/6.022*10^23 gram.