[eml-dev] [Fwd: Re: EML units - pH]

[Inigo San Gil]

Agree. A mol(e) is a number --dimensionless-- 6.023 * 10^23. I.e; one 
mole of potatoes.  A mole of whatever is that outrageously big number of 
whatever.. Other thing is how much weights a mole of oxygen. (Hence the 
reference for "the molecular weight" of elements)

    * An Avogadro's number of standard soft drink cans would cover the
      surface of the earth to a depth of over 200 miles.
    * If you had Avogadro's number of unpopped popcorn kernels, and
      spread them across the United States of America, the country would
      be covered in popcorn to a depth of over 9 miles.
    * If we were able to count atoms at the rate of 10 million per
      second, it would take about 2 billion years to count the atoms in
      one mole.

The man's last name was Avogadro, not that it matters, but to give him 
the credit he did not receive while alive. The scientific community 
ignore his claims in favor to those of Dalton. Dalton was the man in 
vogue during those years, (main claim: the atom is an undivisible 
entity) and Avogadro was.. just plain ugly. His explanations of Gay 
Lussac findings were just ignored. Some websites had different theories 
about why this happened 
http://www.chemheritage.org/EducationalServices/chemach/ppt/aa.html

cheers, inigo




Dan Higgins wrote:

>Hi All,
>    As I learned it, a mole (of anything) is not a mass (grams). It is a 
>_count _in units of Avagado's number (6.023x10^23) Or, as defined by NIST
>
>The mole is the amount of substance of a system which contains as many 
>elementary entities as there are atoms in 0.012 kilogram of carbon 12
>
>It thus really has no units.
>
>Dan
>
>----
>
>Matt Jones wrote:
>
>  
>
>>------------------------------------------------------------------------
>>
>>Subject:
>>Re: EML units - pH
>>From:
>>Matt Jones <jones at nceas.ucsb.edu>
>>Date:
>>Mon, 04 Apr 2005 10:46:18 -0800
>>To:
>>David Balsiger <dbalsiger at wisc.edu>
>>
>>To:
>>David Balsiger <dbalsiger at wisc.edu>
>>CC:
>>servilla at lternet.edu, sheldon at uga.edu, bjbenson at wisc.edu, 
>>pmkapadia at wisc.edu
>>
>>
>>This is a tricky one that we discussed a lot in the eml group but were 
>>ultimately stymied.  Here's the basics as I recall it:
>>
>>pH = -log(moles H/liter)
>>
>>moles H =~ grams because the molecular weight of H is 1
>>
>>thus,
>>
>>pH =~ -log(grams H/liter)
>>
>>For example, for a solution with hydrogen ion concentration of 10^−4, 
>>or 0.0001, moles per liter, the pH is 4.
>>
>>The problem we run into is how to deal with the -log, which doesn't 
>>really change the units.  STMML doesn't really deal with 
>>transformations like this, so we weren't really sure how to either.  
>>The unit seems like it should be -log(moles/l) [or for hydrogen maybe 
>>-log(grams/liter)], but we didn't really know what to make of it 
>>because STMML has no way to express functions such as logarithms as 
>>far as we could tell.  Its possible that transformaitons like this 
>>make the value dimensionless, but I'm not sure.  This problem extends 
>>beyond pH to other similar transformations such as sin, cos, etc., but 
>>pH seems a very common case. STMML probably would need to be extended 
>>with a general purpose expression language that supports common 
>>transformation functions to really define pH.  Suggestions are welcome 
>>on how to handle this in the EML units description.
>>
>>Matt
>>
>>David Balsiger wrote:
>>
>>    
>>
>>>Matt, Mark, Wade,
>>>
>>>Surely someone has determined the correct unit and unit/type 
>>>descriptions for standard pH measurements. Can you save us some time 
>>>and effort in this matter?
>>>
>>>Thanks
>>>Dave
>>>
>>>
>>>Dave Balsiger   Center for Limnology  265-7944
>>>      
>>>
>>------------------------------------------------------------------------
>>
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>> 
>>
>>    
>>
>
>
>  
>