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Structure and thermal expansion of sulfuric acid octahydrate
Author(s) -
MaynardCasely Helen E.,
Brand Helen E. A.,
Wallwork Kia S.
Publication year - 2012
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889812037752
Subject(s) - sulfuric acid , thermal expansion , synchrotron , crystallography , crystallization , crystal structure , aqueous solution , diffraction , powder diffraction , thermal , phase (matter) , chemistry , materials science , mineralogy , geology , inorganic chemistry , thermodynamics , physics , metallurgy , optics , organic chemistry
Synchrotron X‐ray powder diffraction has been used to structurally characterize crystallization products from 37.8 and 40.5 wt% aqueous sulfuric acid solutions. It is confirmed that, despite speculation in the literature, the structure that predominately crystallized from these solutions is sulfuric acid octahydrate (SAO). The existence of an uncharacterized phase is also noted. It was found that existing models proposed for the crystal structure of SAO did not satisfactorily fit to the data acquired here, and hence a new structure solution was sought. It is reported here that the structure of SAO is contained within a unit cell with I 2 symmetry with a = 7.44247 (11), b = 7.4450 (1), c = 26.1168 (3) Å, β = 125.0428 (7)°, V = 1184.78 (3) Å 3 at 80 K. Data were collected at temperatures between 80 and 198 K, which enabled determination of the thermal expansion of SAO.