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Re: SI Units Stumper
At 01:58 PM 1/16/97 -0600, you wrote:
>RADSAFE'rs:
>
>The following question was printed in the "Wacky Questions" column of Denver's
>Rocky Mountain News, in a year-end column subtitled "Queries that stumped the
>staff." In the column, Rebecca Jones (Miss-Becky@aol.com) and her staff
>research and answer all sorts of questions.
>
>She's stumped on this one, and I am curious as well. From previous postings, I
>know there's a group of units experts reading this. Post your thoughts on the
>list and I'll forward them on to the columnist (with credit to you) or e-mail
>her directly.
>
>Thanks
>Jim Langsted, CHP
>MH Chew & Associates
>Golden, Colorado
>73517.351@compuserve.com
>
>"In the International System of Units, almost everything is defined in terms of
>something universally observable, like specific atomic wavelengths or
>frequencies. There are two exceptions. The kilogram is defined in terms of an
>artifact (which is, I believe, a platinum/iridium cylinder that resides in
>Paris). The other is the mole, which is defined as the number of atoms in 12
>grams of carbon-12, and is thus derived from the kilogram. It seems to me it
>would make more sense to just specify Avogadro's number once and for all, use it
>as the definition of the mole, and define the kilogram in terms of the mass of a
>mole of carbon-12. Why doesn't it work this way? -- J-J Cote, Boulder"
>
According to NIST Special Publication 330, 1991 Edition, "The International System
of Units (SI)":
Unit of mass (kilogram): "... the kilogram is the unit of mass; it is equal to the
mass of the international prototype of the kilogram. This international prototype, made of
platinum-iridium, is kept at the BIPM under conditions specified byt eh 1st fCGPM in
1889."
Unit of amount of substance (mole): "... The mole is the amount of a substance
of a system which contains as many elementary entities as there are atoms in 0.012 kilogram
of carbon 12."
Hope this helps.
Bob
========================================================================
_/_/ _/_/ _/_/_/_/ Robert M. Loesch
_/ _/ _/ _/ _/ US Department of Energy
_/ _/ _/ _/ _/ EH-52, GTN, 270CC
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_/_/_/ _/_/ _/_/_/_/ loesch@spok.eh.doe.gov
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