Talk:Apparent molar property

Definition a bit thin
Opening sentence: "An apparent molar property is a quantity that can be used to calculate a property of a solution." This isn't a definition, and it's pretty vague on top of that. 89.217.0.117 (talk) 12:20, 3 June 2014 (UTC)

I edited this and some other things. The article is still pretty fluffy and watery. 89.217.0.117 (talk) 12:54, 3 June 2014 (UTC)


 * I have now replaced the opening sentence by a more precise and informative version. Dirac66 (talk) 01:10, 14 March 2016 (UTC)

Ternary mixtures - pseudo-component and pseudo-binary mixtures
I think it would be a useful addition to article to present the connection between the concept from this article and the pseudo-component defined by process simulation software when analyzing multicomponent mixtures.--86.125.167.205 (talk) 12:23, 28 January 2016 (UTC)

Pseudobinary systems can occur in solutions with more than one solvent where the molality can be defined as amount of solute in moles per kilogram of mixed solvent.--82.137.8.167 (talk) 23:02, 3 October 2016 (UTC)

Removal of info from article
I notice an insufficiently explained removal of some subsections from article. Please discuss before removing some details from article.--86.125.167.205 (talk) 12:26, 28 January 2016 (UTC)


 * Yes, some of the deletions seem more justified than others. Perhaps if no further reasons for deletion are given, the rest of us can feel free to restore that content which seems justified. Possibly in improved or modified form. See for example my comment below. Dirac66 (talk) 00:14, 30 January 2016 (UTC)

From what can be seen in the history of the article, the removed details refer to apparent thermal expansivity.--5.2.200.163 (talk) 14:20, 11 December 2017 (UTC)

Solvent apparent quantities
I see the sections above and the latest edits to article. They seem to assume that the solvent is not entitled to have apparent quantities defined for it. This is a problematic assumption. Thoughts?--193.254.231.34 (talk) 07:20, 29 January 2016 (UTC)


 * Yes, the mention of solvent apparent molar volume was deleted 1-2 days ago by Eric Kvaalen. I have found one thermodynamics textbook (Rock, Peter A., Chemical Thermodynamics, MacMillan 1969, p.227-230) which includes a graph and table of apparent molar volumes of both components of the two-liquid systems water-glycerol and water-ethanol, but without identifying the components as solvent and solute. Probably this is the way to go since there is no rigorous way to define which is solvent and which is solute. Dirac66 (talk) 00:14, 30 January 2016 (UTC)
 * I see that ref you mention is cited by Handbook of Aqueous Electrolyte Thermodynamics .--85.121.32.1 (talk) 11:25, 11 March 2016 (UTC)
 * I have reread the relevant section of Rock's book (and added the missing page numbers above). The graph and table cited are rather confusing to understand. A clearer mention of the properties of both components is at the bottom of p.229, where he uses the data to calculate the values of apparent molar volume for both water and ethanol in the binary mixture at 50 weight per cent ethanol. Dirac66 (talk) 20:06, 12 March 2016 (UTC)
 * And for another recent reference see Table 4 of this recent paper with detailed data tables for the diethylsulfoxide - methanol system, and also for diethylsulfoxide - ethanol. Dirac66 (talk) 20:20, 12 March 2016 (UTC)
 * I have now added both the above references to the article, so it is clear that yes, one can measure partial molar volumes for both components of the same system. Dirac66 (talk) 01:10, 14 March 2016 (UTC)
 * If both components are considered for apparent quantities, is this consideration limited only to mixture of liquids or it can be applied also to liquid-solid (solute) solutions?--85.121.32.1 (talk) 11:40, 14 March 2016 (UTC)
 * My tentative answer is in the footnote I added: For mixtures of a liquid and a solid, the liquid is usually identified as the solvent and the solid as the solute, but the theory is still valid if the labels are reversed. I think the problem with considering the solid as solvent is that its phase change is ignored. Consider for example aqueous NaCl solution at 25oC. Since liquid NaCl does not exist at this T, the only way to find an apparent molar volume of water would be to compare the solution volume with the volume of solid NaCl at the same T. Does this really make sense for a liquid solution? I would like to know what a reliable reference says. Dirac66 (talk) 22:38, 14 March 2016 (UTC)
 * It seems that phase change is implicitly included when it comes to dissolution. For an ideal solution obtained by dissolving a non-electrolyte solid or gas in a liquid the enthalpy of dissolution equals the enthalpy of fusion.--85.121.32.1 (talk) 10:47, 18 March 2016 (UTC)
 * An opposite aspect involves the solidification of the solution when the liquid freezes and may form a solid solution with the solid solute if they are (partially) miscible in solid state.--85.121.32.1 (talk) 10:57, 18 March 2016 (UTC)

Multicomponent systems

 * In this context of present discussion, what is the situation of apparent quantities when a solid say an electrolyte is dissolved in a mixture of the two liquids like water and ethanol? Is such a case and even more complex ones presented in the source you mention?--85.121.32.1 (talk) 10:37, 2 February 2016 (UTC)
 * In such cases where there is no rigorous way to define which is solvent and which is solute apparent properties can be ascribed to every component.--85.121.32.1 (talk) 12:09, 29 February 2016 (UTC)
 * Now we have changed the subject to three-component systems: electrolyte, water and ethanol all mixed together. So as indicated in the section Apparent molar property, there is no unambiguous definition of apparent molar properties. Dirac66 (talk) 20:20, 12 March 2016 (UTC)
 * I don't quite understand which is the nature of ambiguity of the ambiguity since as mentioned above every component can have an apparent quantity defined for it and the number of equations equals the number of components of multicomponent mixtures.--85.121.32.1 (talk) 11:40, 14 March 2016 (UTC)
 * Or perhaps the supposed ambiguity refers to the possibility of treating multicomponent mixtures as if they were (pseudo-)binary ones when the pure component quantity of a component subtracted from the the quantity of the mixture gives the apparent quantity of the other 2 or generally n-1 components from the multicomponent mixture (like above):--85.121.32.1 (talk) 11:48, 14 March 2016 (UTC)


 * $$ V=V_1 + {}^\phi{V}_{23} \ $$
 * $$ V=V_2 + {}^\phi{V}_{13} \ $$
 * $$ V=V_3 + {}^\phi{V}_{12} \ $$?--85.121.32.1 (talk) 12:08, 14 March 2016 (UTC)
 * I do not understand these equations because I don't know what is meant by $${}^\phi{V}_{23} \ $$ It is the apparent volume of components 2 and 3 combined, but how exactly do we divide it into the separate effects of components 2 and 3? Actually I can think of more than one possible way, but I have no idea what is actually done in the solution thermodynamics literature. Again we need some reliable sources. Dirac66 (talk) 22:38, 14 March 2016 (UTC)
 * The possibilities can be enumerated but the division of the apparent quantities of more than one component could be unnecessary at some point (or perhaps could be done by finding the relation between $${}^\phi{V}_{ij} \ $$ and $$ {}^\phi{V}_{i} \ $$). Two or more components from a multicomponent solution can be grouped together (as if they were) (a)s single component. It seems that this is done (at least) for freezing-point depression of more than one electrolyte in a single solvent. Of course sources could be helpful.--85.121.32.1 (talk) 11:25, 18 March 2016 (UTC)
 * Examples of analysis of ternary systems in sources indicated at WP:RD/S Reference_desk/Science.--82.137.11.191 (talk) 21:59, 25 October 2017 (UTC)
 * Link update at RefDesk Archives: Reference_desk/Archives/Science/2017_October_21.--82.137.8.95 (talk) 15:12, 29 October 2017 (UTC)

I see the most recent edits to article involving a recently noticed source. In these conditions I think that at least some if not all of the content removed in 28th of January this year could be reinserted back with necessary adjustments if needed.--85.121.32.1 (talk) 15:40, 18 July 2016 (UTC)
 * The problem was that the content removed was unsourced, as is some of the content retained. If you can find sources for some of the removed content, go ahead and restore it. Dirac66 (talk) 00:07, 19 July 2016 (UTC)

I also think that the source recently linked on talk:Activity coefficient regarding sugar salt solutions could be cited as well.--85.121.32.1 (talk) 15:45, 18 July 2016 (UTC)
 * This reference from Food Science may be useful as a source. Perhaps you would like to read it over and see if you can find some material of interest for the article. How does it treat ternary solutions? Dirac66 (talk) 00:07, 19 July 2016 (UTC)

I think this section would be reasonable, if the terms included in the definition of the "pseudobinary" ternary system are defined. As it stands, is V_2, for instance, supposed to refer to only the volume of pure component 2. Then what does V_{12} mean? Alsosaid1987 (talk) 01:44, 24 November 2017 (UTC)
 * Actually neither V_2 nor V_{12} are used in this article. There are several other more-or-less similar symbols which are used, and it is difficult to know which you mean. On a subject like this it is important to use precise notation, so please copy the source code of the symbols you are asking about onto this talk page so that your question will be clear. I do agree that the sentence which you tagged for clarification is unclear also. Dirac66 (talk) 00:28, 26 November 2017 (UTC)
 * Is the tagged sentence clearer now as result of the rewording?--82.137.14.196 (talk) 01:31, 28 November 2017 (UTC)

Relation to activity coefficient of an electrolyte
It seems that there are some relations between an apparent quantity such as apparent volume of an electrolyte divided to the molar volume of the solvent and the statistical part of its activity coefficient in concentrated solutions, as in the source mentioned there on coefficient page. Can someone access the full text of that source to extract more info?--82.137.10.13 (talk) 14:42, 31 August 2016 (UTC)

Sums of apparent (molar) quantities
It is useful to add to article the sums of individual components apparent quantities and the link to the sums of clustered components apparent quantities $${}^\phi{V}_{ij} \ $$ and $$  {}^\phi{V}_{i} \ $$.--82.137.12.253 (talk) 13:59, 17 October 2017 (UTC)

This relation involving summing is needed for consistency of calculations, similar to the more known sum of mole fractions or mass fractions which is constant, namely 1.--ElectroChem-Al(NiCuZn)82.137.15.27 (talk) 13:07, 4 December 2017 (UTC)

Link to volume fraction
The apparent quantities of components point to a link to the types of volume fraction and volume concentration of components which can be written in order to underline the deviation from additivity of ideal mixtures.--82.137.12.253 (talk) 14:07, 17 October 2017 (UTC)

Relation to mixing ratio - to be included
Also the relation to mixing ratio is a useful inclusion to article.--82.137.12.253 (talk) 14:49, 17 October 2017 (UTC)

Clarification needed for a numerical value
In the subsection Apparent molar property there is a numerical value of 1.055 L/kg for specific volume of the mixture, assumed to be ideal, with 20% ethanol. How is this value obtained?--82.137.15.167 (talk) 23:51, 17 October 2017 (UTC)

The previously mentioned question also appears at Reference_desk/Archives/Science/2016_May_5 by User:Tevildo.--82.137.15.167 (talk) 00:02, 18 October 2017 (UTC)


 * I have now added the explanation of the 1.055 L/kg to the Alcohol subsection of the article.

More context from the source by Apelblat
I think that more context, useful to the subject of the article, could be extracted from the cited source Citric acid, by Appleblat Apelblat. What is the motivation/situation that leads to the use of the subject of the article in a book/monograph(?) written for a particular substance (citric acid)?--82.137.9.225 (talk) 12:43, 18 October 2017 (UTC)


 * The motivation appears from p.50 of Apelblat's book. He and a coworker measured the densities of ternary systems containing citric acid, and proceeded to use the data to calculate and interpret apparent molar volumes. This requires a clear definition which he stated on p.50, as well as an alternative definition on p.320. Last year I included this reference in the article because it had the clearest statement of the two definitions which I was able to find in a Google search. Dirac66 (talk) 00:52, 19 October 2017 (UTC)

I think a closer analysis of the context from this source is necessary in order to clarify the aspects re the non-additivity error, mentioned in a section below. --ElectroChem-Al(NiCuZn)--82.137.10.87 (talk) 12:33, 4 December 2017 (UTC)

Incomplete identification for reference
The reference added today is identified as E. Glueckauf (1955) in the journal Transactions of the Faraday Society: We need the volume number, page number and title please. I tried to find this source with Google and found a list of papers here by Glueckauf which includes three 1955 papers in this journal. Which (if any) is the correct one please? Dirac66 (talk) 03:06, 15 November 2017 (UTC)


 * That, I presume, from pages 1235-1244 titled The influence of ionic hydration on activity coefficients in concentrated electrolyte solutions.--82.137.14.210 (talk) 14:04, 17 November 2017 (UTC)
 * A small problem re this source is that it is behind a paywall. It could be accessed as full text in order to add some additional details into article.--82.137.14.210 (talk) 15:01, 17 November 2017 (UTC)


 * I have formatted the bibliographic information using Wikipedia's Cite journal template, and added the title and the DOI. However unfortunately my university does not seem to have access to this journal so I can not check the formula myself. Could you define the symbols in the formula: γs (activity coefficient?), h, ν, r? Only b = molality has already been defined in the article. Dirac66 (talk) 20:21, 18 November 2017 (UTC)

Non-additivity error
The section Multicomponent mixtures or solutions now claims for the pseudobinary method that The apparent molar volumes of each of the two solutes are then


 * $${}^\phi\tilde{V}_1 = \frac{V-V(solvent + solute\ 2)}{n_1} = \frac{V-(V_0 + V_2)}{n_1}$$ and a similar equation for $${}^\phi\tilde{V}_2$$

The first fractional expression here correctly defines the apparent molar volume of component 1 by this method. However the second expression incorrectly assumes that volumes are necessarily additive, so that the solution of solute 2 in the solvent (water) equals the sum of volumes of solvent before mixing and solute 2 before mixing. If this were always true, the theory would be much simpler. But usually it is not true because the molecules are subject to different intermolecular forces in the pure state and in the solution, so that the mixing involves a change of volume (and other properties as well). I will now remove the incorrect equations for all three components. Dirac66 (talk) 21:58, 3 December 2017 (UTC)


 * What says, for instance, the Apelblat source re this? Is there a distinction between the need to subtract all other individual component's volumes from the volume of the mixture to obtain the apparent volume of the considered component i and the pseudobinary (or pseudo(n-1)) mixture approach which involves mixtures with n-1(n-2) components to be mixed in a certain mixing ratio to obtain the proper mixture with n>=3 components? In this case of submixtures volumes to be subtrated from mixture volume a specification of the mixing ratio is necessary! On the other hand, of course it is simpler to define the apparent quantity of each component i to be the difference between the volume mixture and all other components volumes in n-ary mixtures! A simple starting point is useful! In this discussion about non-additivity combinatorial aspects are unavoidable!--ElectroChem-Al(NiCuZn)--82.137.10.87 (talk) 12:59, 4 December 2017 (UTC)

I have rechecked the source Apelblat and found that it says about this type of calculation like that described above that is unsatisfactory.--82.137.13.62 (talk) 15:24, 6 June 2018 (UTC)

Conditions to meaningfulness
I notice that the formula for solvent apparent quantity has been removed based on the reason that it needs the solutes to be liquid thus in the same state of matter like the liquid solvent in order that solvent apparent quantity be meaningful! So I wonder about the supposed conditions of meaningfulness, are they really necessary for a quantity already (quasi)fictitious like the apparent?--ElectroChem-Al(NiCuZn)82.137.14.182 (talk) 13:29, 4 December 2017 (UTC)

Derivatives of apparent (molar) volume to temperature and pressure
I've just encountered a source, rather dense in formulae/equations, containing among other aspects, mentions re the derivatives of apparent (molar) volume with respect to temperature and pressure, aka apparent molar thermal expansivity and apparent isothermal compressibility: http://acta-arhiv.chem-soc.si/53/53-3-274.pdf. I think this would be a useful addition to this wikiarticle.--5.2.200.163 (talk) 13:54, 11 December 2017 (UTC)

I have browsed the above mentioned source Apelblat finding that it contains expressions with partial derivatives (of volume etc.)--109.166.136.19 (talk) 11:48, 13 June 2018 (UTC)

Three-liquids systems
I see in a section above the source P. Rock which mentions the case of apparent properties for both components of two-liquid(s) mixtures. What is the case for three-liquids mixtures/systems like water-glycerol-ethanol? Is the apparent property of a liquid component from these ternary systems the difference between the volume of the mixture and volumes of the other two components as pure components before mixing?--Electrochem-Al(NiCuZn) 82.137.8.69 (talk) 22:49, 14 January 2018 (UTC)

Relation to molality
I think the relation to molality would need further details about intermediate steps in derivation.--5.2.200.163 (talk) 13:45, 3 August 2018 (UTC)

Beside the mentioned equation in article, there is another in some sources:


 * $$\tilde{V^\phi}_1 = \frac{1}{d} - \frac{d - d_0}{\varrho_1 d_0},$$

where d, d0 densities of solution and solvent, varrho_1 mass concentration of solute.--5.2.200.163 (talk) 14:15, 3 August 2018 (UTC)

The previous equality is considered equivalent to that in article, requiring clarification:


 * $$ {}^\phi\tilde{V}_1 = \frac{1}{b}\left( \frac{1}{\rho} - \frac{1}{\rho_0^0}\right) + \frac{M_1}{\rho_1}$$.--5.2.200.163 (talk) 14:19, 3 August 2018 (UTC)

Both equalities appear in a source article in Food Chemistry (journal), 122(2010), p 455-461.--5.2.200.163 (talk) 14:28, 3 August 2018 (UTC)

An intermediate form would be:


 * $$ {}^\phi\tilde{V}_1 = \frac{1}{n_1} (\frac{m}{\rho} - \frac{m_0}{\rho_0^0}) + (?)\frac{m_1}{n_1 \rho},$$--5.2.200.163 (talk) 15:39, 3 August 2018 (UTC)

from specific volumes v, v0
 * $$ {}^\phi\tilde{V}_1 = \frac{1}{n_1} (m v - m_0 v_0) = \frac{1}{n_1} (V - V_0)$$--5.2.200.163 (talk) 16:19, 3 August 2018 (UTC)