I was responding to this:
No, that's backwards. A mole is 6.02x1023 atoms. Atomic weight happens to have a perfect quantity-to-mass ratio due to scientists being awesome.
because it's not true. (Avagadro's constant is 6.02214129(27) * 1023 mol-1 where the (27) represents uncertainty as to the actual value)
Long and short of it;
1 mole is defined by SI as the number of atoms in exactly 12g of C-12.
AS A RESULT, a mole of any substance will weigh (to within experimental error) the same as the molecular weight
1 of a substance.
My statement was a specific one; it is true, but it does not fit the exact (and thus more general) definition. Hence, Putnam is half right, my definition is backwards. That said, it was good enough for this thread, and it didn't need to turn into a fight over our respective e-science-peen.
2 Also, I have absolutely no idea where he pulled the perfect ratio bit from; it's an experimentally derived number and thus cannot be 'perfect'.
1I should have used this, not atomic weight, in my original post, my bad. Atomic weight is only true when talking about elemental substances. Which doesn't change the point, since I was referring to an elemental substance, but still, we should aspire to the general case.
2A fight I will win, bitches!
4 years of chem/physics undergrad, and 7 months into my science PhD equips me well for meaningless science fights