Open AccessStructure and thermal properties associated with some hydrogen bonds in crystals. IV. Isotope effects in some acid phosphates
Author(s) -
A. R. Ubbelohde,
Ida Woodward
Publication year - 1942
Publication title -
proceedings of the royal society of london. series a, mathematical and physical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.814
H-Index - 135
eISSN - 2053-9169
pISSN - 0080-4630
DOI - 10.1098/rspa.1942.0014
Subject(s) - monoclinic crystal system , hydrogen bond , crystallography , deuterium , crystal structure , chemistry , hydrogen , kinetic isotope effect , thermal expansion , isotope , lattice (music) , crystal (programming language) , materials science , molecule , atomic physics , physics , organic chemistry , quantum mechanics , computer science , acoustics , programming language , metallurgy
The isotope effect has been measured for (NH4 )H2 PO4 . Expansion of the crystal lattice takes place on substituting deuterium for hydrogen. The expansion is in the direction of the hydrogen bonds, and is of the same magnitude as in the isomorphous KH2 PO4 . A contraction of the lattice at right angles to the plane containing the hydrogen bonds is considerably larger for (NH4 )H2 PO4 than for KH2 PO4 . From an application of the calculus of errors, the accuracy of the results is estimated to beα 11 = + 0.00269 ± 0.00006,α 33 = - 0.00123 ± 0.00009. Further investigations on the monoclinic form of KD2 PO4 has shown the presence of curious diffuse reflexions in moving-film photographs. Attempts to obtain (NH4 )D2 PO4 or KH2 PO4 in the monoclinic structure were unsuccessful.