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arxiv: 2605.25895 · v1 · pith:D2OEIZZXnew · submitted 2026-05-25 · ⚛️ physics.chem-ph

Excess molar enthalpies of (iodobenzene, or 1-iodonaphthalene + n-alkane) liquid mixtures at T = 298.15 K and p = 93 kPa

Fernando Hevia , Luis Felipe Sanz , Juan Antonio Gonz\'alez , Daniel Lozano-Mart\'in , Susana Villa This is my paper

Pith reviewed 2026-06-29 19:27 UTC · model grok-4.3

classification ⚛️ physics.chem-ph
keywords excess molar enthalpyiodobenzene1-iodonaphthalenen-alkane mixturesdispersive interactionsDISQUAC modelFlory modelliquid mixtures
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The pith

Excess molar enthalpies of iodobenzene or 1-iodonaphthalene with n-alkanes are positive and show dominant dispersive interactions that strengthen with larger halogens.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper measures excess molar enthalpies for mixtures of iodobenzene or 1-iodonaphthalene with heptane, decane, dodecane, and tetradecane at 298.15 K and 93 kPa. These enthalpies are positive across all systems, indicating that interactions between like molecules outweigh those between unlike molecules. The data point to dispersive forces as the primary interaction type, with strength increasing as the halogen atom size grows due to higher molecular polarizability. The enthalpies are accurately described by both the DISQUAC and Flory models, which also supports largely random mixing under the Flory approach. Derived isochoric excess internal energies follow patterns seen in other cyclic molecule plus alkane mixtures.

Core claim

The measured excess molar enthalpies are positive for all the studied mixtures of iodobenzene or 1-iodonaphthalene with n-alkanes, showing that interactions between like molecules predominate. Dispersive interactions are dominant, and they increase in strength with increasing size of the halogen atom due to the rise in molecular polarizability. Both the DISQUAC and Flory models provide accurate descriptions of the enthalpy data.

What carries the argument

Excess molar enthalpy measurements by Tian-Calvet micro-calorimetry, interpreted via DISQUAC and Flory models to identify dispersive interaction dominance and evaluate random mixing.

Load-bearing premise

Previous excess molar volume data can be combined with the new enthalpy measurements to compute isochoric excess internal energies without large errors from uncertainties or mismatched conditions.

What would settle it

New excess molar enthalpy measurements at equimolar composition that yield negative values or show no increase in magnitude with larger halogen atoms would contradict the claims of positive enthalpies and strengthening dispersive interactions.

read the original abstract

Excess molar enthalpies ($H_{\text{m}}^{\text{E}}$) for iodobenzene, or 1-iodonaphthalene + heptane, + decane, + dodecane, or + tetradecane mixtures at 298.15 K and 93 kPa have been measured using a Tian-Calvet micro-calorimeter. The values of $H_{\text{m}}^{\text{E}}$ are positive and indicate that interactions between like molecules are prevalent. In contrast, our previous results on excess molar volumes ($V_{\text{m}}^{\text{E}}$) are negative for the systems C$_6$H$_5$I + heptane, or 1-iodonaphthalene + n-alkane, which reveal the existence of large structural effects in such solutions. This set of measurements has been used to determine isochoric excess molar internal energies ($U_{V\text{m}}^{\text{E}}$). In the range of n-alkanes considered (n is the number of C atoms of the alkane), values of $U_{V\text{m}}^{\text{E}}$ at equimolar composition decrease from n = 7 to n = 10 and then slightly increase for systems with C$_6$H$_5$I, while decrease slowly for mixtures with 1-iodonaphthalene. These trends fit well with the patterns observed for other alkane mixtures containing cyclic molecules. Dispersive interactions are dominant and those between aromatic molecules with a given halogen atom become stronger when the size of this atom increases due to the corresponding increase of molecular polarizability. The mixtures were studied using the DISQUAC and Flory models. The latter was also applied to n-alkane solutions with C$_6$H$_5$F, or 1-methylnaphthalene. Both theories describe accurately the $H_{\text{m}}^{\text{E}}$ data. In terms of the Flory model, this means that the random mixing hypothesis is largely achieved. On the other hand, the theory overestimates the interactional contribution to $V_{\text{m}}^{\text{E}}$, particularly for systems with C$_6$H$_5$X (X = F, I).

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The paper reports new experimental measurements of excess molar enthalpies H_m^E for binary liquid mixtures of iodobenzene or 1-iodonaphthalene with n-heptane, n-decane, n-dodecane, or n-tetradecane at T = 298.15 K and p = 93 kPa, obtained with a Tian-Calvet micro-calorimeter. All H_m^E values are positive. These data are combined with previously published excess molar volumes V_m^E to obtain isochoric excess molar internal energies U_Vm^E, whose equimolar-composition trends (decrease from n=7 to n=10 then slight increase for iodobenzene systems; slow decrease for 1-iodonaphthalene systems) are compared with other cyclic + alkane mixtures. Dispersive interactions are concluded to dominate, strengthening with halogen polarizability. Both the DISQUAC and Flory models are applied and stated to describe the H_m^E data accurately, while the Flory model overestimates the interactional part of V_m^E.

Significance. If the calorimetric data and the derived U_Vm^E trends are reliable, the work supplies new thermodynamic information on halogenated-aromatic + n-alkane systems that supports the dominance of dispersive forces and the consistency of U_Vm^E patterns across cyclic + alkane families. The direct use of a Tian-Calvet calorimeter and the joint analysis with prior volume data constitute concrete experimental contributions. The reported accurate representation by both DISQUAC and Flory is a positive result for model applicability under the random-mixing hypothesis.

major comments (2)
  1. [Abstract and Results/Discussion] Abstract and Results/Discussion sections: the equimolar U_Vm^E trends that underpin the interaction-dominance conclusions are obtained by combining the new H_m^E measurements with earlier V_m^E data, yet the manuscript provides no explicit thermodynamic identity (e.g., U_Vm^E = H_m^E − p V_m^E versus a fuller expression involving α or κ_T), no statement of pressure matching between the 93 kPa enthalpy runs and the prior volume measurements, and no combined uncertainty propagation. Because these trends are invoked to confirm the interaction picture and to compare with other cyclic + alkane systems, the omission is load-bearing.
  2. [Experimental] Experimental section: no purity verification data, calorimeter calibration constants, or experimental standard uncertainties (or error bars on tabulated H_m^E values) are reported. Without these, the claim that both DISQUAC and Flory “describe accurately” the measured enthalpies cannot be quantitatively assessed.
minor comments (2)
  1. [Abstract] The subscript notation for U_Vm^E appears inconsistently (U_{V m}^E versus U_Vm^E); uniform typesetting should be adopted.
  2. [Abstract] The abstract states that the Flory model was also applied to C6H5F and 1-methylnaphthalene mixtures, but it is unclear whether these are new calculations or literature values; a brief clarification would help.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We appreciate the referee's detailed review and recommendations. Below we provide point-by-point responses to the major comments, indicating where revisions will be made to strengthen the manuscript.

read point-by-point responses

  1. Referee: [Abstract and Results/Discussion] Abstract and Results/Discussion sections: the equimolar U_Vm^E trends that underpin the interaction-dominance conclusions are obtained by combining the new H_m^E measurements with earlier V_m^E data, yet the manuscript provides no explicit thermodynamic identity (e.g., U_Vm^E = H_m^E − p V_m^E versus a fuller expression involving α or κ_T), no statement of pressure matching between the 93 kPa enthalpy runs and the prior volume measurements, and no combined uncertainty propagation. Because these trends are invoked to confirm the interaction picture and to compare with other cyclic + alkane systems, the omission is load-bearing.

    Authors: We agree that an explicit statement of the thermodynamic relation is necessary for clarity. The isochoric excess molar internal energy was calculated using the standard approximation U_Vm^E = H_m^E - p V_m^E, which is appropriate given the low pressures involved and the small magnitude of the pV term. Both the enthalpy and volume measurements were performed at pressures close to atmospheric (93 kPa and approximately 100 kPa, respectively), so the pressure mismatch is negligible. We will add the explicit identity, note the pressure consistency, and include a brief discussion of the combined uncertainty in the revised manuscript. This will allow readers to better assess the reliability of the U_Vm^E trends. revision: yes

  2. Referee: [Experimental] Experimental section: no purity verification data, calorimeter calibration constants, or experimental standard uncertainties (or error bars on tabulated H_m^E values) are reported. Without these, the claim that both DISQUAC and Flory “describe accurately” the measured enthalpies cannot be quantitatively assessed.

    Authors: We acknowledge the omission of these experimental details in the manuscript. Purity of the chemicals was verified by gas chromatography and density measurements, the calorimeter was calibrated using standard procedures with known mixtures, and uncertainties were estimated from replicate measurements. However, these were not included in the original submission. We will add a dedicated subsection on experimental uncertainties, calibration, and purity data, along with error bars or uncertainty estimates on the H_m^E values in the revised version. This will enable a quantitative evaluation of the model descriptions. revision: yes

Circularity Check

0 steps flagged

No circularity: primary results are direct experimental measurements of H_m^E

full rationale

The paper reports new Tian-Calvet calorimeter data for H_m^E at fixed T and p. U_Vm^E values are obtained by combining these measurements with prior V_m^E data via the standard thermodynamic identity; this step is a post-experiment calculation, not a derivation that reduces to fitted parameters or self-citations by construction. Model comparisons (DISQUAC, Flory) occur after data collection and are presented as descriptive fits rather than predictive derivations. No self-definitional loops, fitted-input-as-prediction, or load-bearing self-citation chains appear in the reported chain. The work is self-contained against external experimental benchmarks.

Axiom & Free-Parameter Ledger

1 free parameters · 1 axioms · 0 invented entities

The work rests on standard thermodynamic definitions for excess properties and the applicability of DISQUAC and Flory models to these systems; no new entities postulated.

free parameters (1)
  • DISQUAC and Flory interaction parameters
    Parameters adjusted to describe the measured H_m^E data accurately.
axioms (1)
  • domain assumption Random mixing hypothesis holds sufficiently for Flory model application to these mixtures
    Invoked when stating that accurate description implies the hypothesis is largely achieved.

pith-pipeline@v0.9.1-grok · 5965 in / 1232 out tokens · 32250 ms · 2026-06-29T19:27:12.232110+00:00 · methodology

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Reference graph

Works this paper leans on

3 extracted references

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