Kinetics f the dissociation of hydrogen sulphide by irn films
- 1 January 1966
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Transactions of the Faraday Society
- Vol. 62, 2301-2308
- https://doi.org/10.1039/tf9666202301
Abstract
Hydrogen sulphide is chemisorbed dissociatively at –80°C attaining a maximum coverage of θs 1.6. The hydrogen adatoms at –80°C are metastable with respect to H2(g) for θs values 0.7. Above 0°C, incorporation of sulphur into the metal occurs and the kinetics of dissociation conform to the following equation: –(dPH2S //dt )θs, T =Aθs PH2S //(2πmkT)½ exp (–Eθs//RT ) The condensation coefficient Aθs and activation energy Eθs increase from 10–7 to 101 and from 5 to 20 kcal mole–1 respectively as θs increases from 1.5 to 4.0. A linear relationship exists between log Aθs and Eθs. The slow-step is considered to be dissociation at the sulphide surface and the variation in Aθs is interpreted in terms of the absolute rate theory where the transition state complex gains mobility during sulphidation. The entropy of activation ΔS≠ increased from +5 cal mole–1 deg.–1 1.5 to +30 cal mole–1 deg.–1 at θs 4.0.Keywords
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