Environmental Context. The toxicity of the volatile metal mercury is well known; this Hg⁰ form accounts for about 99% of atmospheric mercury and the remainder the water-soluble oxidized (Hg⁺, Hg²⁺) form. The release of mercury from the atmosphere is measurable by a drop in the Hg⁰ levels, but to establish realistic scientific and regulatory standpoints the rate in which Hg⁰ converts to the oxidized forms needs to be understood. Conversely, from an industrial standpoint, understanding the rate at which the oxidized forms convert to Hg⁰ allows for better waste-scrubbing processes.

Abstract. Theoretical rate constants and activation energies are predicted for the decomposition of mercuric chloride through the use of relativistic pseudopotentials for mercury at the B3LYP level of theory. The method and basis set combinations are validated through a comparison of theoretically determined geometries, frequencies, and reaction enthalpies to experimental values found in the literature. In addition, the theoretically predicted rate constants are compared to rate constants that have been predicted through combustion modelling of this reaction.