The Anomalously High Boiling Point of Water Revisited
- 1Department of Chemistry and Pharmaceutical Sciences AIMMS Vrije Universiteit Amsterdam Amsterdam Netherlands
- 2Institute for Molecules and Materials Radboud University Nijmegen Netherlands
- 3Department of Chemical Sciences University of Johannesburg Johannesburg South Africa
Abstract
Typically, boiling points increase with molecular weight because dispersion forces strengthen. However, H ₂ O deviates from this trend, exhibiting a higher boiling point than its heavier group‐16 analogs. This anomaly is traditionally attributed to water’s larger dipole moment, which is thought to promote stronger electrostatic intermolecular hydrogen bonds. Yet, this textbook explanation lacks quantitative support. Here, alongside thermodynamic and structural effects, we identify a key microscopic, quantum chemical factor that explains trends in interaction strength, which in turn are associated with water’s abnormally high boiling point. Within the series of binary hydrides studied, Kohn–Sham molecular orbital theory reveals that the Pauli exclusion principle is an important factor behind water’s high boiling point, as it modulates intermolecular distances and, thereby, influences the strength of all attractive interactions, including Coulombic attraction. The compact H ₂ O molecule experiences significantly less intermolecular Pauli repulsion, allowing for shorter intermolecular distances, enhancing all attractive forces, and resulting in elevated boiling points. These findings not only provide a rigorous, quantitative framework for understanding a fundamental property of water but also call for a critical re‐evaluation of conventional teaching and interpretation.
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BibTeX
@article{santos2026anomalously,
title = {{The Anomalously High Boiling Point of Water Revisited}},
author = {Lucas de Azevedo Santos and Siebe Lekanne Deprez and F. Matthias Bickelhaupt and Célia Fonseca Guerra},
journal = {ChemistryOpen},
year = {2026},
month = oct,
doi = {10.1002/open.70316},
url = {https://europepmc.org/article/PMC/PMC13661295},
note = {CC BY},
}
RIS
TY - JOUR
TI - The Anomalously High Boiling Point of Water Revisited
AU - Lucas de Azevedo Santos
AU - Siebe Lekanne Deprez
AU - F. Matthias Bickelhaupt
AU - Célia Fonseca Guerra
PY - 2026
DA - 2026/10/13
JO - ChemistryOpen
DO - 10.1002/open.70316
UR - https://europepmc.org/article/PMC/PMC13661295
AB - Typically, boiling points increase with molecular weight because dispersion forces strengthen. However, H ₂ O deviates from this trend, exhibiting a higher boiling point than its heavier group‐16 analogs. This anomaly is traditionally attributed to water’s larger dipole moment, which is thought to promote stronger electrostatic intermolecular hydrogen bonds. Yet, this textbook explanation lacks quantitative support. Here, alongside thermodynamic and structural effects, we identify a key microscopic, quantum chemical factor that explains trends in interaction strength, which in turn are associated with water’s abnormally high boiling point. Within the series of binary hydrides studied, Kohn–Sham molecular orbital theory reveals that the Pauli exclusion principle is an important factor behind water’s high boiling point, as it modulates intermolecular distances and, thereby, influences the strength of all attractive interactions, including Coulombic attraction. The compact H ₂ O molecule experiences significantly less intermolecular Pauli repulsion, allowing for shorter intermolecular distances, enhancing all attractive forces, and resulting in elevated boiling points. These findings not only provide a rigorous, quantitative framework for understanding a fundamental property of water but also call for a critical re‐evaluation of conventional teaching and interpretation.
SN - 2191-1363
ER -