# Talk:Dimensional analysis

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## Simple moles rather than "kg-mol"

Regarding section The factor-label method for converting units, I propose replacing references to "kg-mol" with plain "mol." According to article Mole (unit) linked in the very same section, "kg-mol" is an older term. It is a point of confusion that adds no value to the article. Furthermore, the very next section uses plain "mol" with the same meaning. If no one objects, I will change it in a couple of days.
Christopher Ursich (talk) 22:05, 19 December 2017 (UTC)

The mole commonly used in chemistry, if it needs disambiguation, is the gram mole (g-mol). The kg-mol is 1000 times bigger. It seems that the more commonly used name now is kilomole, following SI prefixing. Gah4 (talk) 00:23, 20 December 2017 (UTC)
You are correct; I missed that. If I were to make the change, I would need to adjust for that factor. That wouldn't be difficult, but I won't press the issue. I do still think, however, that it needlessly makes the content slightly more difficult. I have never encountered this curiously-derived term before, despite being a Chemistry major for a time. Thank you for your input.
Christopher Ursich (talk) 01:18, 21 December 2017 (UTC)
I used to work in a ChE lab, even though I wasn't ChE. In the US, ChE use pound-mole, and chemical reaction energies are in BTU/pound-mole. (Where others would use kcal/mole or eV.) I used to work on a curve fitting program for our lab, which would plot and fit absorption spectra. Previously, it did the x axis in kK (kilo keysers), but I added eV, kcal/mole and BTU/pound-mole, the latter mostly for fun, as I suspect it wasn't used. Gah4 (talk) 01:55, 21 December 2017 (UTC)

What is "kg/kgmol" supposed to be? kg/kg*mol, so mass/mass*mol = 1/mol? How could that be identical to kg/kmol (aka 1000g/1000mol = g/mol = mass/mol)? I can find such expression neither in the mole article nor Stoichiometry. Its does show up in one more article[1] but also with no further information given what this is supposed to be. If this is suppoed to be "kg/kg-mol" as stated in the mole article then it uses the wrong notation here... I will remove this unit and only state the "sometimes" used kg/kmol.

As a side not, this would be the molar mass of NO2 and not NOx, which obviously doesnt have a fixed molar mass. — Preceding unsigned comment added by Eheran (talkcontribs) 10:41, 8 January 2018 (UTC)

I believe that this modification is an improvement. Although we decided to not change the text in this way earlier, I see that the math portion really did need correction. The 'dot' character was being rendered to indicate multiplication of ${\displaystyle kg}$ and ${\displaystyle mol}$, which "kgmol" is not.
Christopher Ursich (talk) 14:47, 8 January 2018 (UTC)
I have wondered about this. Yes, kg mole isn't kg times mole, but, conveniently, a kg mole is 1000 times the size of a gram mole. So, kg mole per kg should equal gram mole per gram. Funny units. Gah4 (talk) 15:17, 8 January 2018 (UTC)
Originally the 'mol' stood for molecule, and might be read as 1/dalton or 1/u. So a kilogram-mole is a number kg/u. Likewise, there was equiv (a mol of valance bonds, so 16 grams of oxygen = 1 g-mol O, or 2 g-equiv O.) A gram-ion was a charge of weight * electron-charge / dalton, so the faraday is a gram-ion, or a gram-mol of electrons. This is used in electroplating, etc. Wendy.krieger (talk) 11:52, 22 January 2018 (UTC)

## Terence Tao article

The above is a bit complicated but might have stuff suitable for the article. The wiki article says "affine quantities" can be subtraced but not added. But I think the mathematical concept wanted is torsors, about which the wiki article is way too technical. The torsors talk page has some more useful links like this one. 173.228.123.121 (talk) 10:07, 4 March 2018 (UTC)

## fractional exponents

Why does the article say the exponents can be arbitrary rational numbers, rather than just integers? Could someone add an example? Thanks. 173.228.123.121 (talk) 08:29, 18 March 2018 (UTC)