H4O5S
sulfuric acid monohydrate · H2SO4·H2O
H4O5S is a thermodynamically stable crystalline form of sulfuric acid monohydrate used in chemical research and industrial acid processing.
About sulfuric acid monohydrate
H4O5S, commonly recognized as sulfuric acid monohydrate, is a thermodynamically stable crystalline phase formed by the hydration of sulfuric acid. As a wide-gap insulating material, it plays a significant role in understanding the phase behavior and structural chemistry of sulfur-based acids.
Its structural diversity is well-documented, with numerous reported configurations across major materials databases. This stability makes it a fundamental subject for researchers investigating the complex interactions within concentrated aqueous acid systems.
Key Properties
Cross-validated computational properties for sulfuric acid monohydrate, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of H4O5S. Tight agreement means computed properties can be trusted without re-running calculations.
Only 1 independent DFT source (materials_project) reports a hull energy for H4O5S, so cross-source agreement can't be assessed yet.
Reported Structures
Lowest-energy structures reported for H4O5S, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| P21/c (No. 14) | monoclinic | 5.65 | 0.0000 | -5.727 | 2.05 |
| Pc (No. 7) | monoclinic | 5.64 | 0.0040 | -5.723 | 1.91 |
| P212121 (No. 19) | orthorhombic | 5.68 | 0.0043 | -5.722 | 2.04 |
| P1 (No. 1) | triclinic | 6.50 | 0.0079 | -5.719 | 2.05 |
| P1 (No. 1) | triclinic | 6.24 | 0.0150 | -5.712 | 2.01 |
| P1 (No. 1) | triclinic | 5.37 | 0.0174 | -5.709 | 1.90 |
| Pc (No. 7) | monoclinic | 5.39 | 0.0246 | -5.702 | 1.90 |
| P1 (No. 1) | triclinic | 5.26 | 0.0292 | -5.697 | 1.93 |
| Pc (No. 7) | monoclinic | 5.29 | 0.0406 | -5.686 | 1.81 |
| P21/c (No. 14) | monoclinic | 5.26 | 0.0548 | -5.672 | 1.79 |
| P21/c (No. 14) | monoclinic | — | — | — | 2.00 |
| P21/c (No. 14) | monoclinic | — | — | — | — |
Applications
Where sulfuric acid monohydrate is used.
Frequently Asked Questions
Common questions about sulfuric acid monohydrate, answered from cross-validated data.
What is H4O5S?
H4O5S is a thermodynamically stable crystalline form of sulfuric acid monohydrate used in chemical research and industrial acid processing.
What is H4O5S used for?
What is the band gap of H4O5S?
Is H4O5S a metal, semiconductor, or insulator?
Is H4O5S thermodynamically stable?
What is the crystal structure of H4O5S?
What is the density of H4O5S?
How many polymorphs of H4O5S are known?
What elements does H4O5S contain?
Where does the data for H4O5S come from?
How It Compares
As a distinct hydrate phase, H4O5S represents a critical point of stability within the broader landscape of sulfur-oxygen-hydrogen chemistry, serving as a benchmark for understanding how water molecules integrate into the acidic lattice structure.
Data sources & attribution
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
- nomad — Data from NOMAD (nomad-lab.eu). Cite: Draxl & Scheffler, J. Phys. Mater. 2, 036001 (2019). (CC-BY-4.0)
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