title: Fractionation of hydrogen isotopes between crystalline hydrates and saturated solution of cobalt dichloride.
abstract: The hydrogen isotopic fractionation factors between the crystal water (CW) in crystalline hydrates and the saturated aqueous solution of cobalt dichloride, alphaCW-st.sol, were experimentally determined in the temperature range from 10 to 55 degrees C under equilibrium condition: alphaCW-st.sol in cobalt dichloride hexahydrate, CoCl2 x 6H2O, from 10 to 43 degrees C, and in cobalt dichloride dihydrate, CoCl2 x 2H2O, at 50 and 55 degrees C. The empirical relationship between ln alphaC.W.-st.sol and (1/T2) on the CW of CoCl2 x 6H2O in the temperature range from 10 to 43 degrees C was obtained as: 10(3)ln alphaCW-st.sol=-2.46(10(6)/T2)+17.6. The CW of dihydrate of cobalt dichloride exhibits larger depletion of deuterium than that of hexahydrate. The values of alphaCW-st.sol in CoCl2 x 2H2O are similar to that of CuCl2 x 2H2O and BaCl2 x 2H2O at 25 degrees C. This fact indicates that the hydrogen fractionation factor between the CW and the saturated aqueous solution of cobalt dichloride strongly depends on the structure of crystalline hydrate rather than the chemical species of cation and/or the crystallized temperature.
authors.affiliation: Department of Chemistry, Faculty of Science, Gakushuin University, 1-5-1 Mejiro, Tokyo 171-8588, Japan. 860018@gakushuin.ac.jp
authors.forename: Masahisa
authors.initials: M
authors.lastname: Kakiuchi
mesh_terms: D005591:Chemical Fractionation; D003035:Cobalt / Q000737:chemistry*; D003903:Deuterium / Q000032:analysis*; D006859:Hydrogen / Q000032:analysis*; D008956:Models, Chemical; D014867:Water
chemical_list: D014867:Water; D003035:Cobalt; D006859:Hydrogen; D003903:Deuterium; C018021:cobaltous chloride