Chemistry's Great Failing
A discussion of Avogadro's number (or Avogadro's constant, as some fashion it) yesterday led me to look up what it was, exactly, as I was only able to recall 6.022 x 10²³. Well, I discovered that me not knowing it wasn't a big deal, as even scientists don't know it. Scientists' best expression of it seems to be:
When your "constant" involves a plus-or-minus sign, you have a few issues. I hereby declare this to be the great failing of chemistry. I could blame the physicists, or split blame between the groups, but I'll stick with the chemists.
Now, part of the reason they don't have an exact measurement, is because there is no stable measurement for a gram, which is something I already knew if I'd bothered to think about it. A "standardized" kilogram exists in France, which is supposed to be the basis for all metric weights worldwide, but its weight in reality fluctuates, as cleanings remove weight and contamination increases it. Still, you would think that science would be able to do better than merely getting within 30 quadrillion of the true value (a spread of 60 quadrillion).
I'll give chemists three months to get this worked out or disband their discipline.
(6.022 141 79 ± 0.000 000 30) x 10²³
When your "constant" involves a plus-or-minus sign, you have a few issues. I hereby declare this to be the great failing of chemistry. I could blame the physicists, or split blame between the groups, but I'll stick with the chemists.
Now, part of the reason they don't have an exact measurement, is because there is no stable measurement for a gram, which is something I already knew if I'd bothered to think about it. A "standardized" kilogram exists in France, which is supposed to be the basis for all metric weights worldwide, but its weight in reality fluctuates, as cleanings remove weight and contamination increases it. Still, you would think that science would be able to do better than merely getting within 30 quadrillion of the true value (a spread of 60 quadrillion).
I'll give chemists three months to get this worked out or disband their discipline.
posted by DC | 6:28 AM
3 Comments:
Now, Now lets not get crazy.
First off, if this is the worst thing chemistry is responsible for then it truly is the superior science.
Second, Avogadro's number is actually insanely accurate if you remember that there is no definite mass for any of the subatomic particles and no definite radius for the atom itself. Also, remember the number is derived from a weighted average of all the isotopes which can't be accurate to more than a few digits without counting every isotope. (and good luck with that)
Third it is actually on par with other constants. The mole has an uncertainty of 5.1 ppm. Others:
Speed of light .008 ppm (it is exact sort of)
the faraday 2.8 ppm
electron charge 2.8 ppm
and my favorite
gravitational constant 615 ppm
Ah, so your defense is "It's not our fault we can't figure this out -- look at all the other stuff we can't figure out, either."
The speed of light does have an exact relationship with the meter -- they redefined the meter in terms of it (so that it is exactly299,792,458 m/s). Scientists have somehow been unable to do this with the mole. Moreover, they were able to get nine significant digits before redefining the meter -- the mole still only has six.
Of course, this all pales in comparison to the true science of mathematics. Pi has been calculated to 1,241,100,000,000 decimal places. Getting bored with filling in each and every digit, mathematicians even snuck a peek at the quadrillionth bit of pi (which is 0, if anyone ever asks). Yes, that's right, mathematicians are so amazing that we didn't even need to calculate all the preceding digits before coming up with that one.
All I'm asking is for the number of atoms in 12 grams of Carbon-12 to be found within a margin of error of 1 billion atoms sometime this summer. Is that really so hard?
After you do that, I'll find a physicist to get to work on Big G.
Ah yes they have rediefined the meter but only theoretically. They measure the speed of light in a vacuum--but total vacuum does not exist and any gravitational pull can also slightly adjust the number. Although I will say that the speed of light is the closest.
Tell you what I will meet you half way. You come up with 12 grams of carbon 12 atoms (and only carbon 12) and I will count them for you.
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