Talk:Ion association

Relevance of removed see also topics

The related articles removed from see also by Petergans are not at all irrelevant to the subject of this article. A trace of resentment from my intervention (I should have apologized for that) at Magnetochemistry can be detected in the edit made by Petergans. It is not constructive to hold grudges and to remove relevant topics.--MagnInd (talk) 21:59, 19 April 2012 (UTC)

I'm sorry, I don't see the immediate relevance of autosolvolysis. That is about the way in which solvent molecules dissociate. What has that to do with the way that ions associate in solution? If you can explain why it is relevant, then it should be reinstated.

BTW, I don't bear personal grudges. I may also mention that I've published many research papers on the topic of ion-association (e.g. reference 4); autosolvolysis does not feature at all in any of them. Petergans (talk) 09:02, 21 April 2012 (UTC)

OK, I apologize for a rather faulty inference by not considering the other possible situation.

In the context of competing equilibria autosolvolysis of the solvent and ion association it is useful to know their mutual influence considering that ions from the dissociation of the solvent could associate with those from the dissolved electrolyte in various solvents.--MagnInd (talk) 20:40, 5 May 2012 (UTC)

Quantitative description and competing hypotheses

brought from usertalk:Petergans:

Hi! I've noticed that you are the main contributor to ion association. I was wondering whether the phenomen could be described more quantitatively, in terms of perhaps degree of dissociation/association, van't Hoff factor, osmotic coefficient and the like.--188.26.22.131 (talk) 09:26, 24 July 2013 (UTC)

The quantitative aspect is the same as for any equilibrium constant.For ion pairs of the type A + B = AB, however, it is difficult to find a measurable quantity that allows the concentration of A, B, or AB to be obtained directly. Also, because A and B are ions, the ratio of total concentrations of A and B cannot be varied by simply adding A or B to a mixture; one must add AC or CB. Therefore there are few reliable equilibrium constants in the literature. Indirect methods based on measurements such as osmotic pressure, conductance, etc. have given wildly different values, summarized in Burgess's book.The reason for the discrepancies is that the calculations are model-based and in effect reflect different physical phenomena.Petergans (talk) 09:57, 27 July 2013 (UTC)

Thanks for the comments. There are some aspects which deserve further details to be specified in in the article.--188.26.22.131 (talk) 09:50, 31 July 2013 (UTC)

One of this aspects regards the quantities which can be related to the concentration of ternary ion associates. How could the concentration of this ternary associates be determined?

Other aspect concerns one of the assumptions used in a certain model-based calculation whose validity is questionable in general and especially in the context of concentrated solutions/ion association is that of total dissociation of the electrolyte. Can this supposition which is involved in some determination of the mean activity coefficient be one of the source of the inconsistencies mentioned and other inconsistencies regarding activity coefficient determined through various methods.--188.26.22.131 (talk) 12:43, 31 July 2013 (UTC)

My feeling is that these matters are too complicated to be included in this article. We did some work with the azide ion which showed spectroscopic evidence for the presence of triple ions (D.D.K Chingakule, P. Gans and J.B. Gill and P.J. Longdon, "Spectrochemistry of Solutions, Part 23. Changes of Enthalpy and Entropy in the Formation of Contact Ion Pairs: A Vibrational Spectroscopic Appraisal using Thiocyanate and Azide solutions". Monatsh., 1991, 123, 521-535. Azide is particularly well-adapted to form contact triple ions because both terminal N atoms are equivalent electron-pair donors. There is no adequate theory for concentrated solutions. Petergans (talk) 07:58, 1 August 2013 (UTC)

In cases like these matters a gradual and simplified approach is useful, by emphasizing the macroscopic aspects as well enumerating the possible hypotheses and tentative theories. Perhaps a comparison of concentrated solutions to ionic liquids and molten salts would be appropiate.--188.26.22.131 (talk) 14:36, 1 August 2013 (UTC)

The complexity of the situation is due perhaps to the number of simultaneous solvation and association equilibria involving triplets like

$\mathrm {AB+A^{+}\rightleftharpoons (AB)A^{+}}$,

$\mathrm {AH+B^{+}\rightleftharpoons (AB)B^{+}}$,

$\mathrm {(AB)A^{+}+sS\rightleftharpoons A^{+}(AB)S_{s}}$

S the solvent, s solvation number.--188.26.22.131 (talk) 08:54, 2 August 2013 (UTC)

It's not a question of complexity, but paucity of direct experimental data with which the equilibrium constants can be determined. As I mentioned above, indirect data are extremely difficult to interpret. For example, there is a long-standing controversy about conductivity minima - do they imply the presence of triple ions or not?

This discussion does not belong this talk page. I don't see any way that the topic of triple ions can be elaborated further in the article. Petergans (talk) 10:04, 2 August 2013 (UTC)

I see, it is about competing hypotheses. The discussion could be moved to talk page of the article. Regarding the implication of ionic triples, what other alternative hypotheses are there?--188.26.22.131 (talk) 10:37, 2 August 2013 (UTC)

Geochemical occurence of ion association

Some link concerning this aspect of the subject: doi:10.1186/1467-4866-3-102--188.26.22.131 (talk) 09:43, 2 August 2013 (UTC)

Please include a DOI with any journal citation in order that the abstact can be viewed online. Petergans (talk) 10:17, 2 August 2013 (UTC)

I'm not very familiar with the ways to mention DOI: is the way above appropiate? doi:10.1186/1467-4866-3-102--188.26.22.131 (talk) 10:25, 2 August 2013 (UTC)

Another link: DOI: 10.1021/je300361j--188.26.22.131 (talk) 10:45, 2 August 2013 (UTC)

This and and this are very interesting. Feel free to include them yourself :-). Template:cite journal has a slot for the DOI. Petergans (talk) 20:14, 2 August 2013 (UTC)

Occurence in hydrous molten salts

Some info regarding this aspect could be added to the article.--188.26.22.131 (talk) 09:49, 2 August 2013 (UTC)

Lead revised

• Expanded the opening to give more detail
• Removed reference to the Townsend avalanche as this is irrelevant
• Greek letters as in πhisics are not acceptable

Petergans (talk) 07:59, 13 June 2015 (UTC)

Association (chemistry) listed at Redirects for discussion

An editor has asked for a discussion to address the redirect Association (chemistry). Please participate in the redirect discussion if you have not already done so. Shhhnotsoloud (talk) 11:39, 9 April 2018 (UTC)

Ion association or incomplete dissociation

Is the title ion association equivalent to incomplete (ion) dissociation?--5.2.200.163 (talk) 16:38, 6 August 2018 (UTC)

Overlap with ionic hydration

It seems that there is a partial overlap between ion association and ionic hydration, derived from the properties of ionic solutions. Thoughts of adding more info?--109.166.139.84 (talk) 15:23, 22 October 2019 (UTC)

I see this aspect is mentioned in the section Classification of ion pairs--109.166.139.84 (talk) 18:25, 22 October 2019 (UTC)

Detection with ion transport number

Can this phenomenon of ion association be detected using the measurement of ion transport number?--109.166.139.12 (talk) 01:36, 18 November 2019 (UTC)

I see there is a reference by Fuoss (1957) which says something about conductance data. It is clear that there must be some connection to the ion transport number, as the conductance is connected to ion transport number. So further details are needed, especially re possible ionic triples, but also ion pairs which are non-participating to ionic currents.--109.166.139.12 (talk) 02:05, 18 November 2019 (UTC)

A good question. Obviously there is a connection in principle, but in practice there is a huge gap between our understanding of macroscopic phenomena, such as ion transport and microscopic phenomena such as ion association. This gap cannot be bridged at the present time, even with the aid of the most powerful computers. Essentially the complexity of the various interactions in solution is too great. At the molecular level they comprise ion-ion, ion-solvent and solvent-solvent interactions. Petergans (talk) 10:10, 18 November 2019 (UTC)

I'd say that ion-association as a (complex) chemical reaction occurs also at macroscopic level, in principle the microscopic level of individual ions and molecules is translated or put in correspondence to the microscopic one by considering 1 mole or gram-ion of particles which contains the Avogadro number. Also there is the same correspondence between individual ions who move along the electric field and 1 mole (or equivalent) of each of the ions from a ionic compound.--109.166.139.12 (talk) 12:42, 18 November 2019 (UTC)

I don't disagree. The point that I was making concerns measurements. Measurements of macroscopic properties give information on macroscopic quantities. Spectroscopic techniques (principally infrared and Raman) give qualitative information on microscopic behaviour, such as the formation of ion-pairs, but they are not suitable for quantitative studies because it is excessively difficult to apply Beer's law to those measurements . Petergans (talk) 14:15, 18 November 2019 (UTC)

Interesting aspects in this section. So the measurement of ion transport number is a macroscopic one (?!).The most recent edit to article re the underlining of ion pair diffusion triggers an ideea regarding the effects on the probable decrease of the values of ion transport number measured in concentrated solutions, having high concentration of ion pairs.--178.138.194.180 (talk) 20:50, 30 October 2021 (UTC)

In mixed solvents systems

I think that ion association data should be presented also for mixed solvents systems.--109.166.138.49 (talk) 19:02, 14 December 2019 (UTC)

I was active in research in this area many years ago. At that time I think that all publications on ion-association concentrated on single-solvent systems. It never occurred to us to use anything other than one solvent at a time.

The most interesting co-solvent would be water, but in practice the high dielectric constant of pure water mitigates against ion-association except with salts containing di-valent or tri-valent ions. There are limitations on what can be done because of issues with solubility. Petergans (talk) 00:33, 15 December 2019 (UTC)

It seems that there are two opposite (extreme) situations: the decrease of dielectric constant favoring ion-association but also lowering solubility. I think it is interesting to see data re ion association for a typical electrolyte like sodium chloride in mixed solvents systems like water-ethanol and other alcohols with the alcohol mass percent in the range 1-35%.--109.166.138.49 (talk) 21:50, 16 December 2019 (UTC)

The aspect re the relation between dielectric permitivity and solubility in the context of ion association is interesting to be detailed in article.--109.166.138.49 (talk) 21:56, 16 December 2019 (UTC)

Triple ion formation

I've just noticed an article re the formation of triple ion by Fuoss and Kraus in J. Am. Chem. Soc., 55, 2387 (1933).--178.138.98.154 (talk) 14:18, 28 September 2021 (UTC)

Info from this research article could be added to the wikiarticle.--178.138.98.154 (talk) 15:56, 28 September 2021 (UTC)

The above section re ion transport number triggers the ideea of ion transport number quantity for triple ion units.--178.138.194.180 (talk) 20:57, 30 October 2021 (UTC)

Ion pair dissociation info from conductivity measurements

I have noticed a journal article re the determination of the constant of dissociation of ion pairs evaluated from conductivity https://doi.org/10.1063/1.1698801 .--178.138.192.180 (talk) 20:18, 26 October 2021 (UTC)

This reference contains a prediction, not a fact. The general issue here is that ion-pairing refers to a reaction at the molecular level whereas conductivity is a property of the whole solution. Petergans (talk) 10:22, 27 October 2021 (UTC)

Can a reaction occur only at the molecular level? The mentioned reference compares the prediction with experimental data, thus being citable.--178.138.194.180 (talk) 15:45, 30 October 2021 (UTC)

Of course not. The difference I want to emphasize is between the observation of properties at the molecular level and their prediction from theory. The fundamental issue with all theories is the level of approximation on which they are based. See Debye-Hückel theory#Limitations for details. Petergans (talk) 10:16, 31 October 2021 (UTC)