[Archy12345]

Hey everyone!

I've been searching the net for an answer, but I just can't seem to find one. Does anyone on here know which element's molar mass was determined first? That is, how do we know that 12.01g of Carbon contains 6.022x10²³ atoms?
And how then were the other element's molar masses determined?

Thanks in advance.

[Borek]

Does anyone on here know which element's molar mass was determined first? That is, how do we know that 12.01g of Carbon contains 6.022x10²³ atoms?

Sounds to me like you may be misinterpreting the history of the molar mass.

At the moment we defined mole we already knew relative atomic masses of many elements. Initially they were determined relative to hydrogen, which was selected as the lightest known element, combining with many other elements. If memory serves me well later it was replaced by oxygen as oxygen combines with even more elements, making determination of relative mass easier.

Compare http://en.wikipedia.org/wiki/Mole_(unit)#History

Note that at the time chemists worked mostly with equivalents, as atomic theory was not yet generally accepted.

Another wiki article claims the first list published by Dalton contained hydrogen, oxygen, nitrogen, carbon, sulfur, and phosphorus.

Precise mole definition was added relatively late, to tidy up whole system.