Basic question

Dima Klenchin klenchin at facstaff.REMOVE_TO_REPLY.wisc.edu
Wed Mar 10 11:29:16 EST 1999

:SInce no one seems inclined to answer your question, I will. 

Hmm, a number of people did provide the answer.

>However, I
:would recommend that you find this type of answer in a textbook as it
:should be very easy to find.
:a mol is equivalent to 6.02E23 molecules.

I disagree. ;-)

A mole is a measure of quantity defined in such way as to compare absolute 
number of single molecular entities of having different molecular masses. 
Arbitrary, it was taken to be measured in grams (number of them 
equal to the molecular mass). It *happened* (by the design of the our 
universe) that every mol contains ~ 6.02^23 molecules (called Avogadro's 
number - the arbitrary nature of which is clear from the fact
that it is not whole number, if I remember it correctly). 

IMHO, this way of putting it is more logical.

:therefore a mmol is equivalent to 6.02E20 molecules.
:it refers to an absolute number of molecules.
:on the other hand, M corresponds to a concentration. That is 6.02E23
:molecules per liter. 
:therefore a mM concentration is equivalent to 6.02E20 molecules per liter.

Naturally, there is nothing to add here. 

        - Dima

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