Talk:Mole (unit)/Archive 2

Archive 1

Archive 2

Reorg to shorten lead paragraph

I moved three paragraphs out of the lead. The lead now just has a brief "what" definition and a single "why" paragraph on applications. The three paragraphs went to concepts, standardization and nature of the particles. I think they are all details on par with and not significantly more important than other details in the sections I moved them into.

I hope this will help the reader get the gist than look at the contents if they want to dig in. Johnjbarton (talk) 14:05, 18 July 2023 (UTC)

Oh. I also added a phrase about 2019 redef, simply to serve as a reader guide that the article contained historical info. Any other single sentence could be used. Johnjbarton (talk) 14:48, 18 July 2023 (UTC)

This is headed in the right direction, but I undid that bit about the redef, since that event is, to all intents and purposes, unknown and uninteresting to anyone but science nerds. The redefinition is also not about the mole per se, but about the SI system and its underpinnings, and created the the undue impression that prior to that point the mole did not have nearly the same form as it now has. —Quondum 15:10, 18 July 2023 (UTC)

No problem. Maybe a sentence about our friend Avogadro. Johnjbarton (talk) 15:15, 18 July 2023 (UTC)

Some encapsulation of the history of the mole could be mentioned. That might include reference to more than Avogadro, of course: his contribution was, as far as I can see, not particularly obvious. But I don't think I could do this aspect justice. —Quondum 15:26, 18 July 2023 (UTC)

To try to pre-empt an edit-kerfuffle: the revert referred to in the edit comment had multiple issues beyond those mentioned in the revert comment. I was about to revert it, but was beaten to it. Also keep in mind that dummy edits are to add information that was omitted in edit comments, not for discussion, which belongs on the talk page. —Quondum 17:16, 18 July 2023 (UTC)

My argument is that technical semantics such as "unit" and "entity" do not belong in a lead. I would never use those terms, they are inappropriately complex IMHO. As I said before, is there really a "mole of Wikipedia editors"? If someone can give me a common usage of mole beyond atoms, molecules and energies I will concede error. KISS should rule in a lead.

. Ldm1954 (talk) 19:53, 18 July 2023 (UTC)

As an addendum, to my knowledge there are only four units of energy in involving atoms: kcal/mol, kJ/mol, eV/atom & au/atom. If these are not in the article, it is inadequate. Ldm1954 (talk) 19:59, 18 July 2023 (UTC)

I am sorry for reverting your edit without opening a discussion on this page. That was too blunt, and I apologize for that. The issues that I objected against in that edit were the following: (a) I have no objection to adding the molar energy units to the article, but the process of addition should not begin from the lead section. (b) The first sentence went against MOS:REFERS: The mole is a term. (c) The main objection was however, the definition: It is defined to be 6.02214076×10^23 of the relevant components. The mole is not 6×10^23 atoms or molecules, it contains 6×10^23 of them. Compare with "A dozen is defined to be 12 eggs or other objects", which sounds wrong. A similarly mistaken definition was what started the above "discussion about semantics". (d) I also think that the quantity amount of substance should appear as a link in the opening paragraph.

On the positive side, I find it very reasonable to emphasize that the mole is mainly used for counting molecules and atoms. I also find the current definition with the quotes slighty awkward, and would be happy if such a phrasing could be found which would sound natural, but would not compromise exactness. Jähmefyysikko (talk) 20:33, 18 July 2023 (UTC)

Apologies accepted. However...

2) I know of no use that does not refer to atoms or molecules. My example of a mole of editors.

3) An energy of 1kJ/mol is the energy per atom times 6x10^23. Number, not amount.

4) While for high-schools and early undergrad mole by itself may be used, the main use in science & engineering is as a number, as in kJ/mol or concentration as in 0.1M sulphuric acid.

5) Related to 4) molarity, molar etc need to be mentioned -- mole is not an island.

6) An encyclopedia explains/documents, it should not be rigid. It should follow usage. (The definition of crystals before and after quasicrstals were accepted is a nice example.)

Just a few comments from someone who has had the convert energies from mole to eV or au too many times. Ldm1954 (talk) 03:36, 19 July 2023 (UTC)

As an addendum, a standard definition of amount is:

A quantity of something, especially the total of a thing or things in number, size, value, or extent.

"the sport gives an enormous amount of pleasure to many people"

I know we Brits can sometimes use three words when the Americans use one, but... Ldm1954 (talk) 03:44, 19 July 2023 (UTC)

Here is a mole of electrons: Faraday constant. And I think that everything will be very confusing, especially for the beginners, if we are not dimensionally consistent. Jähmefyysikko (talk) 05:40, 19 July 2023 (UTC)

In the context of photosynthesis, it is also useful to talk about moles of photons. See Photosynthetic efficiency. Jähmefyysikko (talk) 07:48, 19 July 2023 (UTC)

I agree about the word amount being confusing for beginners. Using a word which has multiple usages where the only one that is appropriate is number is bad, F from your English (or American) teacher. KISS

N.B.Your examples are still atomic/mole and are derivative for a mole of atoms/molecules. Ldm1954 (talk) 10:18, 19 July 2023 (UTC)

Also, remember it is always mole of or per mole. A mole of Ne is 6x10^23 Ne atoms; kJ/mole is the energy per 6x20^23 atoms/molecules; Faraday's constant is used for charge for 6x10^23 electrochemical reactions...etc. Ldm1954 (talk) 10:27, 19 July 2023 (UTC)

I am giving up on this. In my opinion this page and related ones such as amount of substance are inappropriately convoluted for no good reason. Let them eat confusion. Ldm1954 (talk) 10:48, 19 July 2023 (UTC)

References to improve the pedagogy

Here are two recent papers written about the mole concept. The first focuses on pedagogy and the second gives a historical perspective:

• Su-Chi Fang et al. Unpacking the Meaning of the Mole Concept for Secondary School Teachers and Students J. Chem. Educ. 2014, 91, 3, 351–356 https://doi.org/10.1021/ed400128x
• Carmen J. Giunta The Mole and Amount of Substance in Chemistry and Education: Beyond Official Definitions J. Chem. Educ. 2015, 92, 10, 1593–1597 https://doi.org/10.1021/ed5007376

I think these could be used to improve the presentation further and to put the SI definition into context. One thing that immediately stands out is that we are missing the connection between atomic mass and moles (in the intro). This should be in the intro, as it explains how moles are counted by weighting the sample. Currently that connection is only implied by the old SI definition. Jähmefyysikko (talk) 05:15, 20 July 2023 (UTC)

Beware of thinking about pedagogical presentations, or even using them as a reference: WP is explicitly and intentionally not pedagogical: it is primarily a reference. A glance at the second reference above suggests that the author is insensitive to the role of dimension in the SI in this context, and both of these references have pedagogy in mind; this has the effect that they will gloss over some aspects to concentrate on others.

The old and new SI definitions are exactly equivalent, up to an unimportant method of establishing the exact size. I would not base any argument on the old–new difference.

I do, however, agree that the connection between the relative atomic mass, the mass of a sample and the amount of substance makes sense in the lead to give a very direct sense of the mole, as these are all direct concepts, and it gives the immediate utility of the concept of a mole. This relationship is, of course, through the molar mass constant, which is conveniently close to 1 g/mol. This could even be presented as how the masses of the compounds in the given reaction relate ("m = M_u n x, where M_u ≈ 1 g/mol."). I would not be inclined use the atomic mass here, since its the connection to amount of substance and to mass of a sample becomes more complicated and abstract. —Quondum 13:52, 20 July 2023 (UTC)

Daltons for mole by weight

@Jähmefyysikko Added a paragraph to the lead connecting dalton (unit) and mole. While this bulks up the lead, which we just put on a diet, I think it can also be used to provide a kind of feeling for mole in use.

However the addition was not exactly correct. A dalton is a mass unit, like a gram. A mole is an amount of substance. The famous 2019 redefinition fixed the amount in terms of a number of atoms/molecules. So one can no longer weigh out precisely one mole. (Actually you never could, which is why they changed the definition).

I made another try, please review. Johnjbarton (talk) 14:29, 20 July 2023 (UTC)

Thanks! However I don't believe this one sentence is true:

* Thus, 18 g of water contains 1 mol of water.

It reads like a definition. We could give the mass or the mol some significant figure; we could add a trailing " ... to within 0.0xx%"; we could say "very close to " or "approximately"; we could find a reference that I'm wrong and that is the definition. We just don't want to leave the impression that the mole is a unit of mass. Johnjbarton (talk) 14:13, 21 July 2023 (UTC)

I removed the word 'approximately', since the previous sentence already tells that "the mass of a water molecule is approximately 18 Da", and I though there is no risk of confusion. But if you think otherwise, please go ahead and restore the word. Jähmefyysikko (talk) 14:19, 21 July 2023 (UTC)

The molecular weight of isotopically pure water with ¹⁶O is 18 daltons, but "water" is not isotopically pure. So the average molecular mass (Molar mass) of water is 18.015 gm / mol.

To avoid two "approximately"s I changed the text again. Also reversed the sense, using "very close" to make it clear that its not equal but also darn nearly. Johnjbarton (talk) 15:48, 21 July 2023 (UTC)

It is within the sigfigs written. Should be close enough. Gah4 (talk) 12:04, 22 July 2023 (UTC)

@Gah4 true, but for a broad encyclopedia audience I think we should not rely on this implicit meaning of "18". We want to be extra clear that mole is not a unit of mass and gram is not a unit of amount. Johnjbarton (talk) 14:52, 22 July 2023 (UTC)

Having recently lost a WP:COMMONNAME argument, instead of what I believed was the correct name, I suspect that in common chemistry usage gram is a unit of amount. Maybe only slightly less common, mole is a unit of mass. Yes they shouldn't be, but that doesn't stop people from doing it when it is convenient. Gah4 (talk) 19:48, 22 July 2023 (UTC)

Is this suspicion based on something concrete? In which context would it be convenient anyway, as clearly one would not say "2 g H2 and 1 g O2 react to form 2 g of water"? Jähmefyysikko (talk) 05:56, 23 July 2023 (UTC)

In the context of working in a chemistry lab, which I used to do. Someone will ask someone else to "weigh out 0.1 mole of NaCl". (0.1M solutions are very common, along with 1L volumetric flasks.) That leaves it to the second person to do the conversion to grams. Most likely, that person has memorized enough molecular weights to do it without looking it up. Gah4 (talk) 11:25, 23 July 2023 (UTC)

A load of nonsense

It is now 2023-05-21. I discovered the article on Avocadro's number a mess, which reference this article on mole. This is also a mess with people on the talk page talking nonsense, so that's probably why the article on mole is now a mess too. Please someone truly knowledgeable correct both the mole and the Avocadro articles. EdwinaTS (talk) 06:23, 21 May 2023 (UTC)

@EdwinaTS To me the article seems reasonable well organized. Can you give us some specific examples of what makes you think there is a "mess"?

Comments on the Talk page are not part of the article, but I don't think it is helpful to describe comments as "nonsense". If you have specific disagreements with references to back them up please post them. Johnjbarton (talk) 19:04, 10 July 2023 (UTC)

@Johnjbarton sorry, when I last read the article it made no sense. It reads fine when I read it again today. EdwinaTS (talk) 02:05, 30 July 2023 (UTC)

Thanks for the update!

Resolved

Johnjbarton (talk) 14:09, 30 July 2023 (UTC)

Archiving broken

Apparently, archiving of this talk page is broken at the moment with one archive page at Talk:Mole (unit)/Archive 1 and another at Talk:Mole (unit)/Archives/ 1. Can somebody please have a look? Tea2min (talk) 05:05, 25 July 2023 (UTC)

Ok my bad. Thanks for the info. I asked for the original Archives/_1 to be moved to Archive_1. I moved Archive_1 to Archive_2. I think that will fix this issue. Johnjbarton (talk) 13:30, 25 July 2023 (UTC)

@Johnjbarton: MaterialWorks did the move you requested. But shouldn't it be the other way around? Talk:Mole (unit)/Archive 2 now has older posts than Talk:Mole (unit)/Archive 1. I can swap them again to fix that. {{replyto|SilverLocust}} (talk) 14:21, 25 July 2023 (UTC)

I will just go ahead and make this fix. Archive pages start with 1, then newer archives are put at 2, etc. {{replyto|SilverLocust}} (talk) 14:48, 25 July 2023 (UTC)

@SilverLocust thanks. The confusion here has to do with the prefix. One was Archives/, other was just Archive. I believe the first archive was Archives/_1 then I set the bot and it should have written Archive_2 but it did not see the first one so it wrote Archive_1.

in any case you fixed it, thanks. Johnjbarton (talk) 16:37, 25 July 2023 (UTC)

Resolved

Johnjbarton (talk) 16:39, 25 July 2023 (UTC)

Erroneous definition of a mole corrected

I decided to comment on the erroneous definition of a mole, which by the way is a SI unit (while Avogadro's number is not), because I have 7 doctorates in chemistry, 6 doctorates in physics and one in theoretical physics and three doctorates in metallurgy, all awarded me by the Royal Melbourne Institute of Technology (RMIT).

My name is Greg McPaul. I currently live in Ashburton VIC Australia after having recently moved from Thornbury.

NA or Avogadro's number, 6.022*10^23, is the number of helium (He) 4 atoms in exactly 4 grams of He4 while a mole, or 6.023*10^23, is the number of carbon (C) 12 atoms in exactly 12 grams of C12.

The discrepancy between the two numbers i.e. between NA and a mole, lies in the difference in the binding energy of each of the two nuclei, namely He4 and C12. Therefore the sub-atomic particles that make up the He4 nucleus are ever so slightly heavier than that of C12. Thus it takes less He4 atoms to compose exactly 4 grams of He4 than it does to compose exactly 12 grams of C12.

In fact if you graph the change in negative nuclear enthalpy, -delta H (the negative change in heat of a nuclear reaction) against the independent axis, being atomic number, you will find an aggressive trend upwards from hydrogen right up to manganese (Mn, atomic number 25) where the curve kind of reaches a local maximum. The very next element is iron Fe, atomic number 26.

Now all those elements trending upwards are fusable, meaning they spontaneously release heat as the nuclei of these elements' atoms are fused together. The fact is you can rip the nuclei of these atoms apart (with the exception of Hydrogen), but you will have to add at least the amount of energy into their nuclei as the amount of energy that was dissipated upon their fusing.

Upon their fusing however, the amount of mass wrapped up in their sub-atomic particles as mass energy was greater before their fusing than afterwards. This is because the small amount of mass difference was converted to energy according to Einstein's famous equation E = mc^2.

The opposite is true about all the fissile elements i.e. those elements heavier than Mn, inclusive of Fe which is ever so slightly fissile. Upon graphing the -delta H of these elements you will find they pick up where Mn left off but the trend of the graph is ever so slightly negative, right down to your heaviest elements such as plutonium and uranium.

So in summing up, if you were to come up with a new number by which to measure amount of substance, let's say McPaul's number NM, for let's say Mn, I would predict this number to be close to say 6.025*10^23. But to be on the safe side, then between say 6.026*10^23 and 6.024*10^23. Laoscala27 (talk) 18:53, 22 September 2023 (UTC)