An X-Ray Diffraction Study on an Aqueous Solution of CdSO4 at 9 and 62 °C

Abstract

The X-Ray scattering of a 2 M aqueous solution CdSO4 has been measured at 9 and 62 °C in a “Θ-Θ” transmission arrangement with a plane-parallel liquid sample. The experimental distribution curves show main peaks at about 1.5, 2.3, 2.8, 3.5, and 4.35 Å. The 3.5 A peak reveals the formation of inner sphere cadmium-sulphate complexes Cd(H2O)6-z(OSO3)z +2-2z, in which oxygens from sulphate groups substitute z water molecules of the hydrated Cd(H2O)6 2+ ions. Least squares refinements of the i(s) curves are consistent with a structural unit in which the sulphate tetrahedron shares a corner with one cadmium octahedron with Cd-O-S angle of 133 deg. The average number (z) of coordinated sulphate ions increases with increasing temperature.