A HIGH-TEMPERATURE PHOTOCHEMISTRY STUDY OF THE H + HCL-]H2 + CL REACTION FROM 298-K TO 1192-K

Rate coefficients for the reaction between ground-state H atoms and HCl have been measured using the HTP (high-temperature photochemistry) technique. The hydrogen atoms were generated by flash photolysis of NH3, and the relative atom concentrations were monitored by time-resolved resonance fluorescence. The data in the 298-1192 K range are well fitted by the expression k1(T) = 2.8 X 10(-11) exp(-2082 K/T) cm3 molecule-1 s-1 with 2sigma precision limits of +/-6% to +/-12%, depending upon temperature, and corresponding 2sigma accuracy limits of about +/-23%. A transition state theory calculation based on a semiempirical London-Eyring-Polanyi-Sato potential energy surface leads to excellent agreement with the experimental results. By combining the present best fit with current equilibrium data, we derive for the reverse reaction k-1(T) = 4.9 x 10(-11) exp(-2567 K/T) cm3 molecule-1 s-1.