KINETICS OF GROUND-STATE CD REACTIONS WITH CL-2, O-2, AND HCL OVER WIDE TEMPERATURE RANGES

Reactions of ground-state Cd(S-1) have been investigated in the 10-80 mbar pressure range using the high-temperature fast-flow reactor (HTFF R) technique. The Cd + Cl-2 --> CdCl + Cl reaction yielded k(466-875 K ) = 9.0 x 10(-10) exp (-5959K/T) cm(3) molecule(-1) s(-1), with a 2 si gma precision of about +/-15% and corresponding accuracy of +/-27%. Fo r Cd + O-2 and Cd + HCl reactions the upper limits are k(300 K) < 1 x 10-(15) cm(3) molecule(-1) s(-1), or < 5 x 10(-34) cm(6) molecule(-2) s(-1). Orbital symmetry rules are used to deduce the reaction products and, along with electron configuration arguments, help explain the sl owness of the latter two reactions. The importance of these results fo r the speciation of Cd, Hg, and Zn in waste incineration is discussed, and the consequences of the present findings for transition metal rea ctions are mentioned.