# User talk:Dirac66

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User talk:Dirac66/Archive 1 (2006-2010)

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## Symmetry text

Deferring to your probably better instincts, I admit to being irked by the recent insertion by an author pitching his textbook on symmetry into Molecular symmetry. It seems to be an unfortunate precedent. --Smokefoot (talk) 20:01, 31 December 2014 (UTC)

I have now followed the hint given by Bunkerpr's edit summary and looked at the original publication on permutation-inversion groups by H.C. Longuet-Higgins, Molec. Phys. 6, 445 (1963) The symmetry groups of non-rigid molecules [on-line at http://dx.doi.org/10.1080/00268970110088695, with a new volume number and year! it was actually written in 1963.] The key word in the title is non-rigid - Longuet-Higgins proposed his method to classify spectroscopic levels of molecules moving between equivalent multiple geometries, such as inversion of NH3 or hindered rotation of C2H6. For single geometries there is no advantage over the usual method, and no reason to refer to this method as true symmetry.
So since this is an extension of the usual simpler method to a more general case, I propose (soon) to replace the confusing sentence in the opening paragraph by a section at the end named perhaps Extension to non-rigid molecules, and explain the objectives of this unusual method. My source would be Longuet-Higgins' article, though Bunker's book could serve as an additional reference as long as the original source is given first. Dirac66 (talk) 00:38, 3 January 2015 (UTC)

## Electrovalency

While browsing under categories, came across this article today: Electrovalency. Seems like a synonym for ionic (electrovalent bond=ionic bond. electrovalent charge=ionic charge). The article is also mostly an orphan. Any ideas what to do with it? Probably merge or create sections under existing articles that link to it?--Officer781 (talk) 02:38, 6 April 2015 (UTC)

Yes, electrovalency is just an old-fashioned synonym for ionic bonding. So I would suggest merging it into the Ionic bonding article: transfer any content which is not already in Ionic bonding, and mention somewhere in the intro that electrovalency is an alternate name. Dirac66 (talk) 10:58, 6 April 2015 (UTC)
Done. Thanks!--Officer781 (talk) 11:27, 6 April 2015 (UTC)

## Carbenes and free radicals

Is carbene a free radical? I see that the list at octet rule has carbenes separated from free radicals. I'm confused about the definition of free radical. Is free radical a species with an open valence shell? Or is it one with unpaired electrons (which then also includes those with closed valence shells like nitric oxide)? Or a confused mix of both? I don't think the article on wikipedia helps much either (since it gives the definition unpaired or (ie, ∪) open shell).--Officer781 (talk) 02:27, 9 April 2015 (UTC)

Hm. I learned that a free radical is a species with unpaired electrons. A triplet carbene has two unpaired electrons so is a diradical, but a singlet carbene has no unpaired electrons so is not a radical at all.
However I am not 100% certain that I am correct and up-to-date, so it would be wise to check some books. And remember that the definition has changed with time - 100 years ago a radical meant an unstable fragment of a molecule, no matter how many electrons it had. Dirac66 (talk) 02:42, 9 April 2015 (UTC)
The IUPAC definition seems to omit the open shell requirement (it's simply just unpaired electrons). So I've updated the free radical article accordingly and removed that as a category in the octet rule page (some radicals fulfill octet, some don't).--Officer781 (talk) 03:08, 9 April 2015 (UTC)

## Valence shell definition

It is said in the octet rule article (and I'm sure some other Wikipedia articles) that a transition metal's d orbitals are counted in the valence shell. What exactly is the definition of valence shell? Because the article electron shell defines valence shell as the outermost shell (ie the highest principal quantum number) and that is different from valence electrons. Certain usages outside Wikipedia seem to imply valence shell is simply the orbital levels that encompass valence electrons. So we have two conflicting definitions here.--Officer781 (talk) 05:40, 11 April 2015 (UTC)

Yes, the chemical literature is sometimes contradictory which makes it difficult to write consistent Wikipedia articles. The original definition was the shell with the highest principal quantum number, as per Bohr, Sommerfeld, Lewis and Langmuir etc. But chemists often disagree - certainly in VSEPR the valence shell for Ti includes all the valence electrons, both 4s and 3d. So I think Wikipedia should adopt a neutral point of view (WP:NPOV) and point out explicitly that both definitions are used, preferably with sources for each definition. Dirac66 (talk) 15:42, 11 April 2015 (UTC)

## New article

I've made a new article Sigma-pi separation to cover an area I thought Wikipedia did not sufficiently expound on. Could you take a look and help improve on it? Thank you.--Officer781 (talk) 15:35, 13 April 2015 (UTC)

I think this new article confuses historical and current aspects, which are both dealt with in other articles. In the early days of quantum chemistry (say 1930-1960), computers were very primitive so the quantum chemists made many drastic approximations. Sigma-pi separation was used in the Hückel method for planar organic molecules as a reason to do calculations separately for only the pi orbitals which are perpendicular to the molecular plane. Sigma orbitals in the plane were neglected with the attitude that well, they are just localized bonds which we already understand and the pi orbitals are the objects of interest. It was understood that this approximation is often drastic, but the available computers limited what could be done. This historical aspect of the subject is already mentioned at Hückel method.
The current aspect of the article concerns the best simple description of multiple bonds, lone pairs, etc. We can of course now include all the orbitals in the computations, so the question is just whether simple explanations should use sigma and pi orbitals, or (s-p) hybrid orbitals. This is not really concerned with sigma-pi separation, just with whether or not to describe the molecule using sigma and pi orbitals. And as already pointed out in other articles which you have edited, the two descriptions are equivalent for closed-shell ground states but not for ionized or excited states.
So my advice would be to replace the article by a redirect to Hückel method for the historical aspects, and to cover the current aspects in other articles on bonding, hybridization, etc. Dirac66 (talk) 15:00, 14 April 2015 (UTC)
Actually, the section on double and triple bonds were initially covered in bent bonds and I felt an extended version covering lone pairs was necessary. There was also a description of mixing sigma and pi at localized molecular orbitals that could also do a description so I thought of creating this article. I've renamed it "sigma-pi model" and redirected the old name to Huckel method. I'll go ask some other users and get a consensus.--Officer781 (talk) 02:39, 15 April 2015 (UTC)
Yes, I agree that Sigma-pi model is better than Sigma-pi separation. Dirac66 (talk) 20:14, 15 April 2015 (UTC)

## Transfer material from chemical bond to covalent bond

I feel that the article as it is currently is too extensive for a general article in my opinion. Sections such as "Valence bond theory", "Comparison of valence bond and molecular orbital theory" and "Bonds in chemical formulas" could really do better under the covalent bond page. Should a content transfer be done? Moreover, the wikimedia tool specifying the hit rate shows that covalent bond is higher on the list. Those guys would be missing out on important info.--Officer781 (talk) 15:29, 18 April 2015 (UTC)

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## Magnetic moments

Do we have a page with a table of magnetic moments vs electron count? And then perhaps discussion of corrections for spin-orbit coupling? Part of the problem (at least for me) is that the magnetism articles are heavy on the physics.--Smokefoot (talk) 23:59, 30 April 2015 (UTC)

I have just found this subject at Magnetochemistry#Theoretical calculation for complexes of metal ions. Since observed values are considered as well as, I suggest changing the section title to Magnetochemistry#Complexes of transition metal ions. Also we could make the article (or article section) easier to find by adding See also links to related articles, including Magnetic moment, Coordination complex and d-electron count. Dirac66 (talk) 01:33, 1 May 2015 (UTC)

## Delocalized electrons and aromatic ring current

I've recently changed the delocalized electron article to a disambiguation as there are multiple meanings of the term which I feel mean different things in different fields that are often confused (it can be delocalized but static, which means it cannot conduct electricity (unlike the term used for metals and graphite). Delocalization ie resonance is different from delocalized molecular orbitals, also for example as there are delocalized molecular orbitals where there is no resonance.). The old article did have a link. It mentions aromatic ring current, whereby on reaching the page I am told that it is because of the delocalized pi electrons. But these electrons are in discrete energy levels unlike graphite (which has a half filled pi conduction band consisting of a fully filled bonding band and an empty antibonding band with no band gap). This is not an area I'm knowledgeable in but I highly doubt the absurdly simple explanation on that page conflating the chemical definition of delocalization with the conduction definition used in physics (ie mobile electrons). It almost begs to ask the question why non-aromatic ring systems don't create a ring current as they can be depicted by delocalized molecular orbitals.--Officer781 (talk) 10:55, 9 May 2015 (UTC)

You may have confused two types of electric current. Solid-state electronic conduction of electricity over macroscopic distances does normally involve MO's delocalized over macroscopic distances and partly filled conduction bands. However the article on aromatic ring current concerns current flowing around a single molecule such as benzene under the influence of a strong magnetic field in an NMR experiment. This current involves (pi) electrons in the usual benzene ring molecular orbitals and does not require a continuous energy band. Of course it cannot be detected with an ammeter as it is confined to a single molecule, but it is observable by its influence on the NMR chemical shift of the C or H nuclei. See Chemical shift#Factors causing chemical shifts.
Re the absurdly simple explanation, please copy the dubious sentences here so I will know what you are referring to.
And re non-aromatic ring systems: For a ring current, the electrons do have to be mobile within the molecule. This is not true in a ring with localized bonds such as cyclohexane. Dirac66 (talk) 22:49, 9 May 2015 (UTC)
So mobility of electrons does not have to do with continuous bands? Okay that clears it up. Thanks! The absurdly simple argument now holds, I was mixing it up with the other meaning of delocalization (ie the bonding meaning not the mobile meaning).--Officer781 (talk) 02:47, 10 May 2015 (UTC)

## July 2015

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## Boric acid

I have returned very briefly. Greenwood does describe boric acid as strong acid in its dissolution in anh. sulfuric. The formation of tetra(hydrogen sulfato) boric acid is described in Superacid Chemistry By George A. Olah, G. K. Surya Prakash, Jean Sommer, Arpad Molnar,and the dissolution in anh. sulfuric has apparently a measurable H0 of -13.6. NNG may well have missed out the word "Lewis" in his book as I believe he favored the Lewis acid model for the behavior of B(OH)3 rather than Bronsted (-OH- abstraction). Anyway in the absence of any mechanistic evidence for the reaction pathway that I could find I have removed the debatable acid/base description. Regards. Axiosaurus (talk) 15:25, 3 August 2015 (UTC)

OK, thanks. I agree that just giving the equation without the acid/base description seems best here. It is more complicated than either a simple acid or a simple base. Dirac66 (talk) 18:06, 3 August 2015 (UTC)

## Singlet oxygen

Could you please take a look at Talk:Singlet oxygen? Specifically the new edit that indicates that through some mechanism (that I am not smart enough to understand) singlet oxygen is not diamagnetic. --Smokefoot (talk) 00:24, 13 August 2015 (UTC)

I think the 2012 edit by 195.126.85.201 had the correct explanation, even if the references given turned out to be irrelevant. In chemistry there are two types of electronic angular momentum which can interact with a magnetic field - orbital and spin, as in the quantum numbers ml and ms for the H atom. For O2(1Δg), the singlet indicates that the net spin is zero, but the Δ means that the orbital angular momentum ML (sum of ml for 2 electrons) = 2. The diagram in the article for the 1Δg may be helpful: the electron configuration is σs2 σs*2 σp2 π4 π*2. There are two π* orbitals, one corresponding to orbital motion in each direction. The two electrons shown as red arrows are both in the same orbital with opposite spins, so they both have the same orbital angular momentum and the total is nonzero, and they can interact with a magnetic field.
This is written quickly with no source-checking. I will try to find a better source before commenting on the article talk page. Dirac66 (talk) 01:12, 13 August 2015 (UTC)
Thanks very much. The tip-off is the Δ ground state arising from the degeracy of the π*. So the EPR transition (selection rule being ΔMS = 1) is to the state described still by ML = 2 but with MS = 0? --Smokefoot (talk) 13:09, 13 August 2015 (UTC)
I think the general selection rule is ΔMJ = ±1, where J = L + S (vector sum), or for a linear molecule J = Λ + S where Λ is the component of L around the molecular axis. For most radicals of interest L (or Λ) = 0 so J = S and ΔMS = ±1, and in that case EPR is also known as ESR. But for singlet delta oxygen, S = 0 so J = Λ = 2 and the selection rule is ΔML = ±1. Dirac66 (talk) 13:35, 13 August 2015 (UTC)
And note also that there are other molecules for which both L and S are non-zero. See for example Magnetochemistry#Complexes of transition metal ions. Dirac66 (talk) 15:06, 13 August 2015 (UTC)
I cant think of any long-lived complexes akin electronically to singlet O2, anyway Jahn Teller would kick in, it seems. One aspect that I learned from your explanation is that PhNO (nitrosobenzene) is an imperfect model for singlet oxygen, despite some claims otherwise, because its noncylindrical geometry lifts the degeneracy of the pi and pi star. Again many thanks, also about the more general EPR selection rules. On that note I will digress by suggestion that it would be nice idea to have a SpecBox (akin to a ChemBox) for spectroscopic techniques wherein we would state selection rules, energies, time-scales. --Smokefoot (talk) 22:53, 13 August 2015 (UTC)
Specbox is an excellent idea. We could also add type of excitation and type of system studied. And wavelength and frequency even though these are equivalent to energy. Dirac66 (talk) 23:28, 13 August 2015 (UTC)

## Please have a look

I have a longstanding stalker, someone who reverts me almost in real time when I am making chem edits. It is purely personal, insofar as other chem editors routinely see and read the same text, and leave it. It dates back to me editing this editor's "owned" steroids article. Then he followed me to the natural products article, and has since repeatedly followed me, real time when he is on, or same day, to many, many articles that I sit when I log in. I have repeatedly had to drop editing at articles, because of his following me about.

I am not asking you to get involved in the personal issue. But his latest revert of my work came as I was trying to develop the ledes of both the triplet and singlet articles in parallel, before leaving it off to someone such as yourself to continue with. (I am an OChem and early preclinical drug discovery prof and pharma worker, and not a PChem/IOChem expert.)

I would ask you to look at the edits this editor made to the lede at the singlet oxygen article, in particular, the large redaction of material. I would also have you compare the ledes of the triplet oxygen and singlet oxygen articles to see what I was doing, before he followed me to there and removed the developing parallel structure between the articles (by removing and changing the lede of the singlet article).

Here are links: [1] and [2] (note parallel language), and [3] (note that editor's change to paragraph opening, which paralleled the triplet article, and the removal of the entire introductory paragraph). That latter paragraph was intended as temporary, so that others could move material into the main body, as the Edit summaries and Talk section indicates. (But, it was not intended for part-and-parcel elimination.)

Three closing notes -- (i) I added another citation to your paramagnetic discussion at the singlet oxygen talk page. (ii) I came today to edit the lede in question, in particular to remove citations, which I have since transferred to the Structure section (so they do not have to be repeated in the lede). Still, the Structure section is weak, and needs expert attention from you or a colleague. (iii) I am signing this from URL to prevent the editor from stalking me here as well. I can be found at User:Leprof_7272. Le Prof 71.201.62.200 (talk) 17:17, 18 August 2015 (UTC)

I have now looked at this talk page which has become rather heated of late. Perhaps all involved should try to restore calm - no one owns a Wikipedia article and sometimes we have to negotiate compromises. In this case I think the other editor's 3 (only) recent edits do not seem so terrible. I am not so sure why there must be parallel articles on triplet and singlet oxygen. Since triplet is the ground state, I would have expected the triplet nature to be just one section of a longer article on dioxygen, including other topics such as respiration, liquid oxygen, etc. etc. Singlet on the other hand is an excited state of great interest (plus one higher excited state of less interest), so I would expect that the Singlet oxygen article contain both the nature of the excited state(s) compared with the ground state, and the various applications. That would be my viewpoint if I were starting a new article, but don't worry - I will not try to impose still another major restructuring of this article. Eventually I would like to insert an answer to the question of why the 1Δ state is paramagnetic. Dirac66 (talk) 23:58, 18 August 2015 (UTC)

## NIST data

Hi! I want to ask how to search the NIST source you mentioned for deuterium hydride heat of atomization, for instance. Is there a search menu? I haven't figured out how to search there. Thanks!--5.2.200.163 (talk) 14:05, 15 October 2015 (UTC)

Hi. The home page for the NIST Chemistry Webbook is at [4]. From the Search Options choose Formula. On the Search by Formula page, enter HD in the box and also choose Thermodynamic Data Gas Phase. From search results choose DH, then Gas phase thermochemistry data. The value given for ΔHf° is 0.32 kJ/mol, which would be ΔH for 1/2 H2(g) + 1/2 D2(g) → HD(g). Dirac66 (talk) 01:01, 16 October 2015 (UTC)

### Bond energies

Does NIST tables include chemical bond energy values? If yes, where on the site can the bond energy of HD be viewed?--5.2.200.163 (talk) 10:45, 22 October 2015 (UTC)

I have not seen bond energies in the NIST tables. One can of course calculate them from the ΔHf values: E(H-D) = ΔHf(H) + ΔHf(D) - ΔHf(HD). Dirac66 (talk) 20:20, 22 October 2015 (UTC)

## Neutron capture energy experimental data

I wonder in connection to the previous section if there are any tables of experimental data re the energy of some neutron capture reactions. Thanks--5.2.200.163 (talk) 10:00, 19 October 2015 (UTC)

The energies are derived from mass differences since for nuclear reactions these are large enough to be measured. For 1H + n → 2H, Δm = 2.013553 u - 1.007825 u - 1.008665 u = - 0.002937 u = - 4.877003 E-30 kg. Therefore ΔE = Δmc2 = 4.376966 x10-13 J = 263.587 GJ/mol. This is huge compared to chemical reaction energies and has clearly not been included in the NIST value for ΔH for forming HD. Dirac66 (talk) 14:26, 19 October 2015 (UTC)
The experimental data of measurements of the heat of neutron capture cannot be substituted by theoretical calculation of any kind. Experimental data are indispensable to verify the conclusions of theories in any experimental situation where theoretical deductions could omit something important and leading thus to discrepancies to the experimental facts. Considering these aspects, I ask again: Are there any experimental heats of neutron capture available, to your knowledge? Experimental data are needed and not theoretical calculations of heat of neutron capture.--5.2.200.163 (talk) 13:34, 20 October 2015 (UTC)
A correlation of experimental data of nuclear reactions heats seems to be presented at decay heat(ref 10).--5.2.200.163 (talk) 13:42, 20 October 2015 (UTC)
The nuclear masses quoted above are experimental values from mass spectrometry. The only theory I used is E = mc2, which is hardly controversial in 2015. And ref.10 of the decay heat article, it only deals with decay of radioactive isotopes and not with the neutron capture reaction H + n → D. Perhaps you can find a calorimetric value for this reaction, but I'm sure it will close to 263.6 GJ/mol as above, confirming that it cannot possibly be included in the 0.32 kJ/mol quoted by NIST. Dirac66 (talk) 15:48, 20 October 2015 (UTC)

## Bare proton cation in solid state

Hi, Dirac66! I noticed your edit from the proton talk (archive) page about proton diameter. I ask you whether there are any compounds which could contain bare proton as cation in solid state.--5.15.187.229 (talk) 10:58, 11 November 2015 (UTC)

No, a bare proton in the solid state is impossible, because the proton is extremely small relative to any atom with electrons, and its electrostatic potential is enormous. Therefore it will attach itself to any nearby electron cloud and become either bonded or solvated. This is already explained at Proton#Hydrogen ion and also at Hydron (chemistry). Dirac66 (talk) 16:58, 11 November 2015 (UTC)
Interesting situation, but I think the situation would be more interesting for bare proton if some sort of entrapment is involved and the counter negative ion is electron like in an electride. Electron is smaller than proton. Surely hydrohelium electride would be a compound with very interesting and (possibly unexpected) properties. Could it be synthesized somehow?--5.15.191.4 (talk) 23:04, 11 November 2015 (UTC)
I don't know, but to insert the subject in Wikipedia we would need a reliable source. Dirac66 (talk) 23:51, 11 November 2015 (UTC)

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## Hydrogen bond energy

Hi! I see in the article hydrogen bond a mention of ion cyclotron resonance for determining the bond energy. Are you familiar with any details of such determination?--5.2.200.163 (talk) 17:31, 10 December 2015 (UTC)

Not really, sorry. I would suggest looking up the cited paper by Larson and McMahon which may explain the experiment. Dirac66 (talk) 19:19, 10 December 2015 (UTC)

## Electron ionic radius

Hi! I wonder if the electron ionic radius in electrides is the same with electron radius in general? Any ideas?--5.2.200.163 (talk) 17:31, 29 December 2015 (UTC)

I think that just defining the electron radius in any system is a complicated topic. In the spirit of quantum mechanics, one should not ask what is the "real" value of electron radius, but rather what value is to be expected in a given experiment, and the answer depends which experiment you choose. Atom-size values from crystallography refer to the size of the volume (or its cube root) which an electron occupies, but other physics experiments are consistent with point-like electrons. And this is true not only for electrides but also for the hydrogen atom, conduction electrons in metals, etc. etc. See also the article on point particle. Dirac66 (talk) 19:41, 29 December 2015 (UTC)
Yes, the electron radius issues are non-trivial. But why isn't the concept of point particle also applied to proton as well for which there are measurements of its radius? What are factors that lead to only electron being considered a point particle and not proton? This question is a natural one.--5.2.200.163 (talk) 10:58, 30 December 2015 (UTC)
The proton was considered an elementary or point particle from the 1930's to the 1960's. But in the 1960's the quark model was proposed, so that the proton is now considered a composite of three quarks. This corresponds to a structure so it is not a point particle, according to the Standard model of modern particle physics. Dirac66 (talk) 11:47, 30 December 2015 (UTC)
Are the concepts elementary particle and point particle identical? If yes, would that mean that from the 1930's to the 1960's proton was assigned a zero radius? When measurements of proton radius (by scattering for instance) have been done? After the 1960's? What is the exact relation between substructure and radius? How do they entail one another? If quarks are true point particle, why not their composite - proton - be also point paticle?--5.2.200.163 (talk) 12:06, 30 December 2015 (UTC)
Good questions, but I am not really an expert on this. These questions are discussed to some extent at point particle. I suggest you read over that article and its talk page, and then post any remaining questions on the talk page there. Perhaps someone else can answer better than me. Dirac66 (talk) 15:07, 30 December 2015 (UTC)
Ok, thanks for the suggestions.--5.2.200.163 (talk) 15:53, 30 December 2015 (UTC)

## Proton conductor

Hi! If, as discussed above a bare proton cation in solid state is impossible, then what is the charge carrier in proton conductors? That article in it present state says that bare proton is the carrier.(!?)--5.2.200.163 (talk) 12:56, 4 January 2016 (UTC)

In proton conductors, current is usually carried by some version of the Grotthuss mechanism of proton hopping. This means that one molecule of a Bronsted base transfers H+ to a second molecule, which transfers (another) H+ to a third molecule, which transfers (another) H+ to a fourth molecule, etc. The net effect is that H+ is transported rapidly, but at no point is the H+ actually bare. I will eventually try to add this point to the Proton conductor article, if no one else does first. Dirac66 (talk) 23:26, 4 January 2016 (UTC)

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## Chembox triple point and critical point fields/parameters request

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## Phase diagram of water

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## Comparative reaction rate and intermediate(s)

Hi! Regarding the difference in hydrogen evolution reaction rate between sodium with liquid ammonia vs sodium with water to what factors can this difference be ascribed? Is it comparable to the difference between water and alcohols re reaction with sodium? (I see that reaction with liquid ammonia requires a catalyst, unlike presumably gaseous ammonia)--5.2.200.163 (talk) 15:56, 9 March 2016 (UTC)

I'm sorry but I know nothing about these reactions. Perhaps if you placed a message on the talk page for sodium amide, someone else might be able to answer the question. Dirac66 (talk) 19:11, 9 March 2016 (UTC)

## Handbook of Aqueous Electrolyte Thermodynamics

Hello! I've seen that you have mentioned a book by P. A. Rock on talk:Apparent molar property which is cited by this Handbook of Aqueous Electrolyte Thermodynamics.

I want to ask if you have acces to the full text of this latter mentioned source in case the missing pages from preview are needed to be cited on Wikipedia? Thanks.--85.121.32.1 (talk) 11:41, 11 March 2016 (UTC)

I have a hard copy of Rock's book which I used many years ago as a course textbook. I have not tried to find this book on the Internet. Dirac66 (talk) 11:52, 11 March 2016 (UTC)

## Humid salt(s) densities

Hi! Are you aware of some data tables re densities of humid solid salts (sodium chloride, etc) as a function of moisture content? Google search seemingly does not give any results.--5.2.200.163 (talk) 15:43, 14 March 2016 (UTC)

If there are some data they could be posted perhaps on sodium chloride (data page).--5.2.200.163 (talk) 15:53, 14 March 2016 (UTC)

Perhaps the data are lacking because a humid solid salt is not a uniform homogeneous system at the microscopic level. Solid NaCl has a well-defined compact structure with no room for any H2O molecules. So if water is in contact with salt crystals, it can dissolve some of the NaCl to form an aqueous solution, and leave the rest as an undissolved solid. The system then has two phases, and quite possibly an extensive interface making it colloidal. In this case the average density (= total mass / total volume) would not be very meaningful. Dirac66 (talk) 20:03, 14 March 2016 (UTC)
Is the situation comparable or not with that of wet sand? Perhaps in such cases the heterogeneous system could be considered pseudo-homogeneous and bulk density can be used.--5.2.200.163 (talk) 14:06, 18 March 2016 (UTC)
I am not an expert in this and I am not aware of any useful data. Wet sand could mean many things at a microscopic level as sand has different meanings. However the most common meaning would be small quartz (silica) crystals in contact with water. I think this would be comparable to wet salt, although the silica structure may have more room than NaCl to accommodate water molecules. Dirac66 (talk) 19:36, 18 March 2016 (UTC)
How does the water activity intervene in this cases? Is it different than the value of mole fraction of water in moist solids?--5.2.200.163 (talk) 14:41, 21 March 2016 (UTC)
Does the comparability of situations need total or partial (i)miscibility in solid state? The solid salt can play the role of the sand and the diluted salt solution that of water. Can ice and salt form mixed crystals?--5.2.200.163 (talk) 14:14, 18 March 2016 (UTC)
At a microscopic level I think ice and salt do NOT form mixed crystals because they have quite different and incompatible structures. Of course one can grind up macroscopic crystals to form a coarse mixture, but as the components get smaller and the surface increases, it should become less stable. That is my instinct but I admit to having no sources. Dirac66 (talk) 19:36, 18 March 2016 (UTC)
One can think of frozen sea water columns and brinicles in this context as examples. The solid solution article says that moist solids can be solid solutions. The question is: Are these moist solids ideal solutions? Or due to sorbtion effects non-ideality occurs as the water activity and moisture sorption isotherm articles seem to suggest?--5.2.200.163 (talk) 14:50, 21 March 2016 (UTC)
I'm sorry but I do not know the answers to this question. Dirac66 (talk) 18:38, 23 March 2016 (UTC)
In non-trivial cases like this one, not knowing is OK. The real problem is how to spot publications in journals that may have addressed the topic given that ordinary googling gives few results.--5.2.200.163 (talk) 12:58, 24 March 2016 (UTC)
What techniques of information retrieval could be applied in this case to detect a starting point? Perhaps (key words) browsing the index of journals such as Journal of Solution Chemistry, Journal of Chemical Thermodynamics, Journal of Chemical Physics, etc?--5.2.200.163 (talk) 14:19, 24 May 2016 (UTC)

## Molecules or compounds in title of an article?

How do you think about the title of this article in connection to an older discussion re molecules vs compounds.--5.2.200.163 (talk) 14:43, 4 May 2016 (UTC)

I think that molecules is the usual term used in astrophysics. One reason would be that several of the species listed are not compounds but elements; the list includes C2, C3, C5, C24, C60(fullerene), H2, N2 and O2. Also there are a number of cations which are not associated with anions to form compounds in the interstellar medium, but instead exist in the presence of free electrons. Dirac66 (talk) 19:45, 4 May 2016 (UTC)
Could substance be used also for stand-alone ions in plasma phase? Should the title of the list underline the microscopic or the macroscopic perspective? The word molecule emphasizes the microscopic view.--5.2.200.163 (talk) 11:47, 9 May 2016 (UTC)
You say about stand-alone cations in presence of free electrons. Can they be included in molecules category according to the present title?--5.2.200.163 (talk) 11:57, 9 May 2016 (UTC)
The term chemical substance technically refers to a pure substance, whereas most plasma phases are mixtures. However usage is not uniform and some authors do describe liquid or solid mixtures as substances, so I suppose some would similarly describe a plasma mixture as a substance. Yes, this is the macroscopic description.
As a microscopic description, the word molecule originally meant neutral molecules, but now is extended to include charged molecules in many contexts. Biochemistry for example. So cations observed in astrophysical or laboratory plasmas can be called (charged) molecules, or molecular ions if you wish.
As for the title of the list, I think the we want the microscopic perspective since it is the individual molecules which are of interest. Dirac66 (talk) 01:47, 10 May 2016 (UTC)

## You are correct

I struggled with that and failed to find the key. Thanks for correction. Grammar's Li'l Helper Talk 20:42, 27 May 2016 (UTC)

Again, nice touches. Love the language. Grateful for the help. Grammar's Li'l Helper Talk 23:41, 27 May 2016 (UTC)
Glad to help. Dirac66 (talk) 23:51, 27 May 2016 (UTC)

## June 2016

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## User page edit heads-up

Was browsing Wikipedia pages and some user pages and noticed that your user page had an IP who edited it with hobbies. Would most likely be you forgetting to log in but I'd thought there'd be the other (very minor) possibility someone edited it and you overlooked it. Heh. --Officer781 (talk) 15:38, 6 June 2016 (UTC)

Thanks. No, that was not me and I had not noticed it before. It should have shown up on my watchlist at the time, but perhaps I didn't see it. Anyway I have removed it now. Dirac66 (talk) 19:16, 6 June 2016 (UTC)

## Possibilities

Hi! I've noticed you said at Talk:Apparent_molar_property#Multicomponent systems about several possibilies of assigning apparent molar properties to more than one component! Can you list or mention some of them that you have in mind?--5.2.200.163 (talk) 15:16, 21 June 2016 (UTC)

Consider a 3-component system such as water-ethanol-sucrose. One way could be to assume 2 components have the same properties as in the pure state, so that the apparent molar volume of sucrose is the solution volume minus the pure-state volumes of the actual amounts of water and ethanol, all divided by the number of moles of sucrose. And similarly for the apparent molar volumes of water and of ethanol.
A second way would be to compare the solution volume with the volume of binary mixtures, so that the apparent molar volume of sucrose is the solution volume minus the volume of a water-ethanol solution with the actual amounts of water and ethanol, again divided by the number of moles of sucrose. This may be more logical as it excludes the effect of water-ethanol interactions in the sucrose apparent molar volume. And similarly for the apparent molar volumes of water and of ethanol. Dirac66 (talk) 22:18, 21 June 2016 (UTC)
I think your reply of could be more easily understood if accompanied by some formulae/algebraic expressions. Or perhaps the text and the associated formulae could be added in the mentioned article or talk page on purely mathematical definitions reasoning grounds without regards to possible or alleged OR status since by WP:CALC formulae derivations and handling are allowed.--5.2.200.163 (talk) 16:24, 8 July 2016 (UTC)
In a simplistic notation: method 1 is VS = [V - nWVW(pure) - nEVE(pure)] / nS, where VJ is a molar volume.
And method 2 is VS = [V - VWE] / nS, where VWE is the volume of the water-ethanol solution without sucrose. Perhaps this is the ${\displaystyle {}^{\phi }{V}_{23}\ }$ written by editor 85.121.32.1 on the article talk page. Dirac66 (talk) 20:34, 8 July 2016 (UTC)
This notation could be improved, but I prefer to wait until I have time to check the library for equations used in textbooks, rather than develop my own notation which is WP:OR. As for the section WP:CALC which you mention, please notice the words provided there is consensus among editors that the result of the calculation is obvious, correct, and a meaningful reflection of the sources. I do not believe that is true in this case, because we have (at least) 2 possible equations for a 3-component system so we can't say that either is obvious. Also it is not clear to me which is correct, and we have not checked reliable sources. Dirac66 (talk) 19:53, 8 July 2016 (UTC)
OK, no hurry to insert in article. Of course this issue could be further discussed in larger venues like WikiProject Mathematics for a clearer understanding. I'd say that the only possibility for defining apparent quantities for a single component in a ternary solution is the first, the second applies for a component in a pseudobinary mixture where the other 2 substances being considered a single one. In our example of pseudobinary the mixture water-ethanol of a certain composition could be assimilated to a fictitious single solvent. By varying the composition of WE from 0 to 1 mass fractions of E a family of fictitious unary solvents could be obtained. This way the ternary (mixture) case can be reduced to the (pseudo)binary case. This can be related to the mixing ratio of different binary mixtures to form the ternary mixture.--5.2.200.163 (talk) 11:04, 11 July 2016 (UTC)
A mixture with n-components can be split in submixtures with arity smaller n by forming the powerset of k-combinations of individual components.--5.2.200.163 (talk) 11:26, 11 July 2016 (UTC)
I have now found one interesting reference here by Apelblat. He mentions the pseudobinary definition first, then offers the possibility of using a (weighted) mean apparent molar volume for the two solutes. Dirac66 (talk) 02:23, 12 July 2016 (UTC)
I see the ref you've found is a monograph titled Citric acid. Could you specify the actual number of page where the book appears in Google search results with the mentioned expression? Also I see that the references for chapter 5 starting from page 345 are not displayed in this preview (section consultable). It would be extremely interesting to know the ref [189] identifier data, as well as other references identifier for this chapter 5 for further details of definitions. Can you somehow view those undisplayed pages in the preview?--5.2.200.163 (talk) 12:50, 12 July 2016 (UTC)
The page number is 320 which I found by scrolling up a few lines. And I found the ISBN = 978-3-319-11233-6 by Googling Apelblat citric acid. But I cannot view the undisplayed pages without paying for the book - sorry. Dirac66 (talk) 15:44, 12 July 2016 (UTC)
If you want to see the refs from a specific chapter, you have to pay for all the book? How much would that be? Another aspect is about Apelblat. You seem to have known/heard about him previously, unlike me who have just heard about him. Could it be contacted by email to provide the list of references of chapter 5?--5.2.200.163 (talk) 15:52, 12 July 2016 (UTC)
No, I don't know anything about Apelblat. I merely use the author's name as a short way to refer to the book, as a much more convenient (and pronounceable) identifier than the very long character string produced by Google. As for paying for the book, some perspective is needed. My computer says about \$150 US for the book, which I will not pay either. Probably the only people who will really pay this price are professional researchers in a related topic. In the age of the Internet, more information is available free (and fast) than ever before, so I was able to find these pages and refer them to you for free. But it is human nature to be greedy so we would all like still more information free, but it is not available. Why is even the little bit available? Because the publisher hopes that the free sample will induce a few researchers to pay for the whole book.
So what should Wikipedia editors do? My advice is to do the best we can with what IS available for free, and perhaps from our university libraries. And we have to just accept that not everything is free and available, and sometimes we will not be able to find answers to all our questions. Sorry, but that is life. Dirac66 (talk) 18:10, 12 July 2016 (UTC)
Where have you encountered first Apelblat as professional author? In a university library? Or perhaps you had some special interest in citric acid?--5.2.200.163 (talk) 13:12, 13 July 2016 (UTC)
I never heard of him until 2 days ago, when I did a Google search on apparent molar volume ternary definition and looked through the results on the first screen. Of the information available from that search without charge, the extract of his book seems the most helpful. Dirac66 (talk) 17:09, 13 July 2016 (UTC)
Can we insert formulae in the article with the content available until now?--5.2.200.163 (talk) 15:56, 12 July 2016 (UTC)
I think we should try to do this. First I plan to check the thermodynamic textbooks in my university library, but if I find nothing useful, then I will eventually write a paragraph based on the Apelblat source. However please feel free to go ahead first if you wish. Dirac66 (talk) 18:10, 12 July 2016 (UTC)
It seems that mathematical intuition is validated by the formulae contained in Apelblat.--5.2.200.163 (talk) 13:35, 13 July 2016 (UTC)
OK, I have now inserted into the article the two methods mentioned by Apelblat. Dirac66 (talk) 01:37, 18 July 2016 (UTC)
Re the pseudobinaries, I'd suggest that the notation be somehow different to be distiguished from the case where all components have an associated apparent quantity not involving pseudobinary, pseudoternary, etc.. A further remark could be made re the request made on the article talk for restoring the content removed at the end of this January: not all derived formulae/statements need sourcing due to the use of WP:CALC. We can take as an example the derivations from mole fraction, they certainly not need sourcing from a pure mathematical point of view.--5.2.200.163 (talk) 14:19, 19 July 2016 (UTC)

I've spotted at least one source that uses notation 123, 12, and |12| for ternary mixtures, binary mixtures and binary grouping in ternary: F. Kohler, Monatsh. , 91, 738, (1960), so it is not a problem to mention the combinatorial approach in article.--5.2.200.163 (talk) 13:46, 16 August 2016 (UTC)

Since you have this article, perhaps it would be best if you suggested the appropriate changes. Either in the article itself or on the article talk page. Dirac66 (talk) 01:37, 17 August 2016 (UTC)

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## Ionic strength fraction

Hi! Have you encountered the term ionic strength fraction (of a total ionic strength)? It is used for solutions of several salts in solvent(s) as a composition variable. It is used in some articles without an explicit definition.--5.2.200.163 (talk) 11:34, 11 July 2016 (UTC)

I'm not familiar with it explicitly, but presumably it just means the fraction of the total ionic strength due to the salt considered. So for the example at Ionic strength#Calculation example the ionic strength fraction of KCl = 0.02 M / 0.17 M = 0.12. This seems a reasonable guess of its meaning. Dirac66 (talk) 15:34, 12 July 2016 (UTC)

## Ideal solution

Regarding the definition of an ideal solution re the additivity of volumes of components on mixing, does the definition imply that the additivity of volumes should hold at all temperatures or not? Can an ideal solution in some temperature range become non-ideal in other temperatures ranges?--5.2.200.163 (talk) 12:06, 11 July 2016 (UTC)

Real examples of almost ideal solutions can become less ideal at other temperatures. Of course if we postulate an unidentified ideal solution, it is assumed to be ideal at all temperatures, and from that assumption we can prove that the volume is additive at all temperatures. But a real example, say ethane and propane, is only approximately ideal, probably in the temperature range where both components are liquid. And the deviations can be larger at other T, say when one component becomes solid or supercritical. Dirac66 (talk) 19:44, 11 July 2016 (UTC)

## Mistaken edit

Thanks for undoing my unintentional edit on neutron. I was previewing various width spaces as digit separators and didn't mean to save it. (Using a mobile device is so much more kludgy than a computer.) Hgrosser (talk) 02:13, 30 August 2016 (UTC)

I understand. And I refuse to own a mobile device. Dirac66 (talk) 13:35, 30 August 2016 (UTC)

## Source Structure of electrolytic Solutions - 1959

Hi! I want to ask seeing your edits on Apparent molar property if the full text of the mentioned source on activity coefficient#Concentrated solutions of electrolytes is accessible to you in order to be able to extract some additional info about the relation between the apparent molar quantities and the activity coefficient of solutes. Thanks.--82.137.10.13 (talk) 14:56, 31 August 2016 (UTC)

Sorry, but I have no access to this book. I have just checked my university library catalog and they do not have it. Dirac66 (talk) 18:51, 31 August 2016 (UTC)