Premium
X‐ray diffraction studies of aqueous solutions of urea
Author(s) -
Adams R.,
Balyuzi H. H. M.,
Burge R. E.
Publication year - 1977
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/s0021889877013454
Subject(s) - urea , aqueous solution , chemistry , diffraction , molecule , x ray , x ray crystallography , hydrogen bond , crystallography , organic chemistry , physics , optics
An X‐ray diffraction method has been used to study the influence of solute concentration on molecular associations in aqueous solutions of urea. Calculations, from experimental intensities, of unsharpened electronic radial distribution functions (RDF) are presented for the range of urea concentration from 0.83 to 16.8 mol Kg −1 (5 to 100% solutions). The changes in RDF with increasing urea concentration are complex. Unequivocal interpretation of the distribution functions is not possible, but the major effect of the relatively bulky urea molecules on the water structure appears to be caused by distortion of the water matrix. At urea concentrations of 50% and 100%, features of the RDF not visible in the RDF's at lower concentrations indicate the presence of long‐range (over a distance of about 8 Å) structural relationships possibly due to urea–urea interactions: such an interpretation would make urea–urea hydrogen‐bonded associations unlikely at lower urea concentrations.