Talk:Colligative properties

By the naming conventions this article should probably be at Colligative property. If no objection, I'll do this. - Taxman ^Talk 16:55, August 1, 2005 (UTC)

They are always referred to in the plural. It would look silly to have 4 properties listed under "Colligative property". Scratchdawg 01:26, 16 August 2007 (UTC)

{Request edit}I believe that a link to a page in my website may be useful here. It is 'Colligative properties of water' at http://www.lsbu.ac.uk/water/collig.html. Martin Chaplin (talk) 09:02, 26 February 2008 (UTC)

The editor Martin Chaplin seems to have left Wikipedia. Both his user page and Talk page were deleted at his own request. Under these conditions I prefer not to add the suggested reference. If he returns, perhaps he can contact me on my own Talk and we can discuss this further. The suggested reference is on a personal site, and the article at present has no other references. I'd rather see a few normal textbooks cited there before we consider self-published ones. EdJohnston (talk) 23:35, 1 March 2008 (UTC)

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Possible plagiarism/copyright violation. Much of the article appears to be copied from [1]. --Iml (talk) 00:16, 7 May 2008 (UTC)

Material seems to have been added by ErkangZhu, reverted to 20:25, 19 April 2008, 24.187.39.87.--Iml (talk) 00:25, 7 May 2008 (UTC)

Steric occlusion

The descriptions here are totally incorrect, and a perpetuation of bad science taught at many colleges and universities. Steric occlusion, or occlusion of any form whatsoever is NOT a proper description of colligative properties!!!!! —Preceding unsigned comment added by 146.79.245.70 (talk) 04:05, 19 July 2010 (UTC)

I have moved the above comment to the end as it was made later than the others. Two years later the article still mentions steric occlusion (blocking) just to say that it is wrong. I agree that it is wrong but why even mention it? The general chemistry texts I have checked (Petrucci et al, Chang, Whitten and Davis) just give the qualitative kinetic argument which we now have based on rates of evaporation and condensation. And the physical chemistry texts give the (approximately) quantitative thermodynamic argument based on the chemical potential. So I have decided to delete (today) all reference to steric occlusion, and add (soon) a mention of the thermodynamic reasoning, though with less detail than the sources. Dirac66 (talk) 19:56, 10 June 2012 (UTC)

as you leave.71.56.73.141 (talk) 04:38, 12 February 2014 (UTC)

Etymology

The given etymology is surely spurious. Although it does appear in some other online sources (and possibly in the source given), the derivation from the Latin "colligere", meaning to bind or gather, indicates that such properties depend only on the concentration of solute and not its structure or chemistry, rather than that the properties are "bound together" by that fact, whatever this might mean! The word "colligative", according to the OED, means relating to the binding together of molecules; that is, colligative properties are so-called because they depend on molecules bound in solution. (I would change this directly, but didn't want to delete the citation out of hand, although the cited source may also be wrong.) 82.46.70.132 (talk) 14:53, 19 June 2013 (UTC)

Hm. I inserted this etymology on 8 June 2012. The exact words of Laidler and Meiser are The properties of dilute solutions that depend on only the number of solute molecules and not on the type of species present are called colligative properties (Latin colligatus: bound together). The phrase bound together by the fact that means related by the fact that or have in common the fact that, but I used bound together since that is the translation of colligatus. This is what I learned as the explanation for the term colligative, and the online sources which I found with Google suggest that other people learned that too, but I will admit that these sources are mostly anonymous and not very reliable.

However the OED explanation does not seem very useful either. If binding together of molecules means bound in solution (by solute-solvent interactions?) as you suggest, then I would point out that there are other properties in solution which are not colligative, e.g. surface tension or viscosity which do depend on the nature of the solute.

A better source might be W.B.Jensen, Journal of Chemical Education 75, 679 (1998) who has traced the historical origin of the term to 1895, when Ostwald classified molecular properties as colligative, additive or constitutional. Jensen explains the meaning of these terms according to Ostwald, and relates them to more modern concepts. He still does not explain exactly why Ostwald chose this term however, and perhaps we should not attempt to explain this point either until we have a more reliable source. Dirac66 (talk) 17:26, 20 June 2013 (UTC)

Thanks. I'd say your quotation from Laidler and Meiser should settle it that it's wrong to say the derivation from colligere consists in the properties being "bound together" by some or other fact, which, as I insinuated above, is unidiomatic, as well as irrelevant: it's the molecules' being grouped together that's responsible for these properties of solutions. Consider, additive and constitutional properties are "bound together" by whatever makes them additive or constitutional! And the same goes for any property. I don't see how the quote supports any etymology other than the one I suggest, although "bound" is a dangerous word to use in scientific contexts. One could as well translate colligere as to gather, collect, or group (I only used the phrase "bound in solution" to mirror the term given in the article, but it does seem plausible that Ostwald - or Wundts: see below - was thinking along those lines in introducing it). The Jensen paper you mention clarifies things further. Some properties of solutions, the colligative ones, depend only on the solute concentration (and temperature) - one might say they depend on the mere gathering together of solute molecules, although that's not very idiomatic either, or scientific; others depend also on the composition of the molecules, which makes some additive or summative contribution to the solution property in question; others depend further on molecular structure, or constitution. I'm not sure I see what you're driving at with your point about surface tension, etc. Yes, these depend on the molecules in solution, but they depend on more than that, and hence are not colligative. This is very clearly expressed by Jensen's hierarchical explanation. Incidentally, as well as the Jensen paper, I discovered Homer W. Smith, "A Knowledge of the Laws of Solutions ...', Circulation, 21 (1960), who gives the date of Ostwald's taxonomy as 1891, although the exposition isn't quite as nice or as rigorous as Jensen's:

'The three interrelated properties of a solution osmotic pressure, freezing-point lowering, and vapor-pressure reduction were, on the suggestion of Wundts, called "colligative" by Ostwald in 1891 (W. Ostwald, Lehrbuch der allegemeinen Chemie, 2nd edn., Vol. 1: Stochiometrie, Book 4: Solutions, p. 30. Leipzig: W. Engelmann, 1891-93. Translated by M. M. Pattison Muir. London and New York: Longmans, Green & Co., 1891). Ostwald distinguished additive, constitutive, and colligative properties: additive properties are those which are the sums of the properties of the constituents (e.g. mass) ; constitutive properties depend on the arrangement of the constituents of a pure substance (e.g. boiling point, optical activity, etc.; colligative properties are those which have equal values for chemically comparable (molar) quantities of the most different substances (e.g. volume and pressure relations of gases, and the aforementioned properties of solutions in which the component molecules are so widely separated from one another that the mutual interactions of these molecules are reduced to a minimum). It was not until 1889 that Beckmann (E. Beckmann, "Studien zur Praxis der Bestimmung des Molekulargewichts aus Dampfdruckerniedrigungen", Ztschr. Phys. Chemie, 4 (1889), p. 532) added boiling-point elevation to the other three colligative properties, the theoretical relationships having been supplied by "my honored friend" Arrhenius.' 82.46.70.132 (talk) 04:17, 21 June 2013 (UTC)

I think the Laidler and Meiser quote does not really explain why the word colligative is used. We seem to be considering three possibilities: (1) colligative means that the properties have some common feature (2) colligative means that the molecules are bound together in some way (3) colligative is (the English translation of) a name chosen by Ostwald along with additive and constitutional, for reasons that are not clear from our sources.

Although (1) may seem illogical to you, there are some sources on the Internet so it does seem to be widely believed. And I have now found one published source which seems more explicit and reliable: E.M. Kramer and D.R. Myers, Am. J. Phys. 80, 694 (2012) which says on p.697 in parentheses: (historically, the word “colligative” was chosen to describe those properties that are bound together by a shared, linear dependence on solute concentration)

As for (2), perhaps reasons can be found for this argument but I am not aware of any sources at all which support it explicitly.

However do we now have very good sources for (3), the colligative-additive-constitutional classification. Your Smith paper and my Jensen paper agree on the essentials, and both trace back the nomenclature to Ostwald. All that is missing is the original German terms (which would be in the original papers), and Ostwald’s reason (if he gave one) for the word colligative (or its German equivalent).

So I propose that instead of the sentence on etymology, we should cite these two sources and say that the word was introduced by Ostwald who classified properties of solutions as colligative, additive and constitutional (at least in English) with a brief explanation of the meaning of each, although only colligative is still used.

The fact that Laidler and Meiser do no more than give the Latin root, and don't explain why the word was coined, is precisely why I thought it didn't support the etymological claim implied by having the citation there. I agree (obviously) that the etymological claim expressed should be replaced, although I think the Latin should be given, just not be explained in the way it currently is. I suspect a few of these internet sources have been feeding off each other and perpetuating the (in my view) mistaken sense of being bound together by a common source. I think Kramer and Myers are just plain wrong, and perpetuating an error from somewhere else. Academics are not immune from such error, and no less likely to get the linguistic facts wrong than the casual reader. I still think it's highly probable that the term was coined because concentration was the only factor affecting the properties in question (concentration and gathering together being related concepts - "they gathered in various parts of the city, but the largest concentration was outside Parliament"). It would have been odd for Ostwald (and Wundt) to have coined three terms for properties of solutions, two of which described their dependence on constituent molecules - additive or constitutional - and one which merely said that the properties "are bound by a common source"; and even more odd that he would use the notion of binding at all to express the latter.

As I say, linguistic sources are usually more reliable for linguistic matters: here's what the OED says, with the original Ostwald quote - no indication that being bound together by a common feature is relevant; the relevant factor is independence from the chemical nature and structure of the groups of substances involved (where grouping is another concept related to combination or gathering together). It gives a different source volume of Ostwald's book from Smith, presumably because he cites the second edition (1891) and this is from the first (1889):

colligative <Latin colligāt-, participial stem of colligāre to bind together ( < col- , com- together + lingāre to bind) + -ive suffix. In sense 2 after German kolligativ (1889 in the source translated in quot. 1890 at sense 2). ...

2. Physical Chem. Of a property or effect: depending on the number of particles present, or their concentration, irrespective of their individual natures. ...

1890. J. Walker tr. F. W. Ostwald Outline of General Chemistry ii. iii. 58 Properties that always retain the same value for definite groups of substances, independent of the chemical nature and number of the atoms in these complexes, I have, at the suggestion of Professor Wundt, named colligative. The volume of gaseous substances, therefore, is such a colligative property. 82.46.70.132 (talk) 05:09, 23 June 2013 (UTC)

I challenge this claim

"Measurement of colligative properties ... can lead to accurate determinations of relative molar masses ..." This needs to be given a good reference, because my understanding is (and I am not "skilled in the art") that the determinations are crude, no better than a few percent. In the context of todays analytical capabilities, the claim that it is "accurate" is not correct.173.189.76.237 (talk) 07:41, 21 August 2013 (UTC)

Yes, I think you are right. Accurate is only a qualitative word, and we need a source which gives a quantitative idea of the errors involved. This is not easy to find since these methods are not used very much today to measure molar mass, at least for substances which can be isolated. For now I will remove the word accurate. Dirac66 (talk) 13:50, 21 August 2013 (UTC)

I also challenge this claim

How is a "colligative property" not just a confusing term for ideal solution? How are these examples only dependent on the number of particles and not the chemical activity, i.e. the identity of the second component? I have always been confused why things like vapor pressure lowering are said to be colligative properties. Isn't this only true for liquids following Raoult's law? Colligative properties are unacceptably broad as described here. Am I missing something? Please clarify or correct. — Preceding unsigned comment added by 169.234.228.156 (talk) 07:49, 26 June 2015 (UTC)

I have added a sentence to the first paragraph to say that the independence of solute nature is exact only for ideal solutions, and approximate for dilute real solutions. Dirac66 (talk) 14:13, 26 June 2015 (UTC)