How did avogadro find the number of molecules in a mole?
Owing to their tiny size, atoms and molecules cannot be counted by direct observation. There are, however, a number of indirect methods that enable us to estimate the number of these particles in a sample of an element or compound. Once this has been done, we know the number of formula units (to use the most general term for any combination of atoms we wish to define) in any arbitrary weight of the substance. The number will of course depend both on the formula of the substance and on the weight of the sample. But if we consider a weight of substance that is the same as its formula (molecular) weight expressed in grams, we have only one number to know: Avogadro’s number, 6.022137 × 1023, usually designated by NA. Things to understand about Avogadro’s number • It is a number, just as is “dozen”, and thus is dimensionless; you can think of Avogadro’s number as the “chemist’s dozen”. • It is a huge number, far greater in magnitude than we can visualize; see here for some interesting compa
