Subtopic Deep Dive
Standard Molar Enthalpies of Formation
Research Guide
What is Standard Molar Enthalpies of Formation?
Standard molar enthalpies of formation (ΔfH°) are the change in enthalpy when one mole of a compound in its standard state is formed from its elements in their standard states at 298.15 K and 1 bar pressure.
Researchers determine ΔfH° values experimentally via combustion calorimetry and computationally using group additivity methods or ab initio calculations. Key studies include Naef and Acree's 2017 group-additivity algorithm for vaporization and solvation enthalpies (67 citations) and Ribeiro da Silva's 1999 enthalpic increments for pyridines (15 citations). Over 10 listed papers span heterocycles, amino acids, and energetic materials.
Why It Matters
ΔfH° values anchor thermochemical databases like NIST-JANAF, enabling prediction of reaction enthalpies in synthesis and catalysis. Naef and Acree (2017) provide group-additivity tools for estimating properties of unmeasured organics, impacting pharmaceutical design (Alantary and Yalkowsky, 2017; 20 citations). Zherikova and Verevkin (2020) developed diagnostics for metal-organic thermochemistry consistency, crucial for energetic materials (Silva et al., 2023). Accurate ΔfH° supports hydrogen carrier thermochemistry (Verevkin et al., 2023).
Key Research Challenges
Experimental Purity Assignment
Assigning SI-traceable purity for organic calibrants affects combustion calorimetry accuracy. Westwood et al. (2023) outline methods for mass fraction purity in IUPAC technical report (39 citations). Errors propagate to ΔfH° values.
Data Consistency Diagnostics
Inconsistent thermochemical data in metal-organics requires diagnostic checks. Zherikova and Verevkin (2020) developed a tool for tris(beta-diketonato)metal complexes (18 citations). Resolving discrepancies demands reinvestigation as in TKX-50 (Silva et al., 2023).
Group Additivity Limitations
Group-additivity methods fail for polysubstituted or strained rings. Naef and Acree (2017) extend algorithms but require validation (67 citations). Ribeiro da Silva (1999) provides increments for heterocycles yet exemptions persist (15 citations).
Essential Papers
Calculation of Five Thermodynamic Molecular Descriptors by Means of a General Computer Algorithm Based on the Group-Additivity Method: Standard Enthalpies of Vaporization, Sublimation and Solvation, and Entropy of Fusion of Ordinary Organic Molecules and Total Phase-Change Entropy of Liquid Crystals
Rudolf Naef, William E. Acree · 2017 · Molecules · 67 citations
The calculation of the standard enthalpies of vaporization, sublimation and solvation of organic molecules is presented using a common computer algorithm on the basis of a group-additivity method. ...
Methods for the SI-traceable value assignment of the purity of organic compounds (IUPAC Technical Report)
Steven Westwood, Katrice A. Lippa, Yoshitaka Shimuzu et al. · 2023 · Pure and Applied Chemistry · 39 citations
Abstract The “purity” of an organic compound typically refers, in practice, to an assignment of the mass fraction content of the primary organic component present in the material. The “purity” valu...
Estimating the Physicochemical Properties of Polysubstituted Aromatic Compounds Using UPPER
Doaa Alantary, Samuel H. Yalkowsky · 2017 · Journal of Pharmaceutical Sciences · 20 citations
Error or exemption to the rule? Development of a diagnostic check for thermochemistry of metal–organic compounds
Kseniya V. Zherikova, Sergey P. Verevkin · 2020 · RSC Advances · 18 citations
A diagnostic tool for checking the consistency of thermochemical data of tris(beta-diketonato)metal complexes is developed.
Recent work on the thermochemistry of some nitrogen heterocycles
M. A. V. Ribeiro da Silva, M. Agostinha R. Matos · 1997 · Pure and Applied Chemistry · 16 citations
Abstract
On the Enthalpy of Formation and Enthalpy of Sublimation of Dihydroxylammonium 5,5′‐bitetrazole‐1,1′‐dioxide (TKX‐50)
Ana L.R. Silva, Ana R. R. P. Almeida, María D.M.C. Ribeiro da Silva et al. · 2023 · Propellants Explosives Pyrotechnics · 16 citations
Abstract The thermodynamic characterization of dihydroxylammonium 5,5′‐bitetrazole‐1,1′‐dioxide (TKX‐50) was reinvestigated. Although TKX‐50 is one of the most promising new‐generation energetic ma...
Thermal behavior and polymorphism in medium–high temperature range of the sulfur containing amino acids l-cysteine and l-cystine
Concepción Foces‐Foces, Marı́a Victoria Roux, Rafael Notario et al. · 2011 · Journal of Thermal Analysis and Calorimetry · 15 citations
A thermophysical study of the sulfur containing amino acids l-cysteine and l-cystine has been carried out by differential scanning calorimetry (DSC). Heat capacities of both compounds were measured...
Reading Guide
Foundational Papers
Start with Ribeiro da Silva and Matos (1997; 16 citations) for nitrogen heterocycle thermochemistry, then Ribeiro da Silva (1999; 15 citations) group additivity increments; Foces-Foces et al. (2011; 15 citations) for amino acid polymorphism effects.
Recent Advances
Naef and Acree (2017; 67 citations) general group-additivity algorithm; Zherikova and Verevkin (2020; 18 citations) metal-organic diagnostics; Verevkin et al. (2023; 13 citations) alkyl-cyclohexane carriers.
Core Methods
Combustion/static bomb calorimetry for ΔcH° → ΔfH° via Hess's law; group additivity (Naef-Acree algorithm); ab initio benchmarks; DSC for phase changes (Foces-Foces et al., 2011).
How PapersFlow Helps You Research Standard Molar Enthalpies of Formation
Discover & Search
Research Agent uses searchPapers and exaSearch to find 250M+ papers on 'standard molar enthalpy formation group additivity', revealing Naef and Acree (2017) as top-cited. citationGraph traces Ribeiro da Silva's 1997-2007 heterocycle series (16+13 citations). findSimilarPapers expands to Verevkin et al. (2023) hydrogen carriers.
Analyze & Verify
Analysis Agent applies readPaperContent to extract ΔfH° tables from Naef and Acree (2017), then runPythonAnalysis fits group-additivity models with NumPy/pandas for prediction errors. verifyResponse (CoVe) cross-checks values against Westwood et al. (2023) purity standards; GRADE assigns A/B evidence levels to calorimetry vs. computational claims.
Synthesize & Write
Synthesis Agent detects gaps in metal-organic diagnostics post-Zherikova and Verevkin (2020), flags contradictions in TKX-50 data (Silva et al., 2023). Writing Agent uses latexEditText to draft thermochemistry tables, latexSyncCitations for Ribeiro da Silva series, latexCompile for publication-ready reports; exportMermaid diagrams reaction schemes.
Use Cases
"Validate ΔfH° of TKX-50 against literature using Python regression."
Research Agent → searchPapers 'TKX-50 enthalpy formation' → Analysis Agent → readPaperContent (Silva et al., 2023) → runPythonAnalysis (pandas regression on cited calorimetric data) → researcher gets error bars and consistency plot.
"Compile LaTeX review of pyridine thermochemistry with citations."
Research Agent → citationGraph 'Ribeiro da Silva pyridine enthalpy' → Synthesis Agent → gap detection → Writing Agent → latexEditText (add increments table) → latexSyncCitations → latexCompile → researcher gets PDF with 1999/2007 papers integrated.
"Find code for group-additivity enthalpy prediction."
Research Agent → paperExtractUrls (Naef and Acree, 2017) → Code Discovery → paperFindGithubRepo → githubRepoInspect → researcher gets Python algorithm for ΔvapH°/ΔfH° estimation.
Automated Workflows
Deep Research workflow scans 50+ papers on 'combustion calorimetry organometallics', chains searchPapers → citationGraph → structured report with GRADE-scored ΔfH° datasets. DeepScan's 7-step analysis verifies Zherikova and Verevkin (2020) diagnostics via CoVe checkpoints and runPythonAnalysis. Theorizer generates group-additivity extensions from Naef and Acree (2017) + Ribeiro da Silva (1999) patterns.
Frequently Asked Questions
What is the definition of standard molar enthalpy of formation?
ΔfH° is the enthalpy change for forming 1 mol of compound from elements in standard states at 298.15 K, 1 bar. Determined by Hess's law from combustion or reaction calorimetry.
What experimental methods measure ΔfH°?
Combustion calorimetry measures ΔcH°, converted via Hess's law; static bomb calorimetry common for organics. Purity assignment per Westwood et al. (2023) ensures traceability.
What are key papers on group additivity for ΔfH°?
Naef and Acree (2017; 67 citations) algorithm for vaporization/solvation; Ribeiro da Silva (1999; 15 citations) increments for pyridines. Alantary and Yalkowsky (2017; 20 citations) UPPER for aromatics.
What open problems exist in this field?
Consistency diagnostics for metal-organics (Zherikova and Verevkin, 2020); extending group additivity to strained rings; reconciling contradictory energetic material data like TKX-50 (Silva et al., 2023).
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