New Experimental Evidence in the Sulphur-Hydrogen Reaction

Abstract

BODENSTEIN¹ studied this reaction in sealed bulbs containing excess of sulphur, and found a temperature coefficient of 1.34 between 234° and 283°, and 1.77 between 310° and 356°. His work was criticised, by Norrish and Rideal², as possibly vitiated by the hydrogen sulphide liberated on the solidification of the residual sulphur, and as leaving uncertain, in view of the variable temperature coefficient, the part played by the walls of the bulbs. These workers employed a dynamic method, and showed that the logarithms of the total reaction velocity—always, however, measured in the presence of nitrogen—when plotted against absolute temperature yielded a curved line. The differences in the velocities obtained, using hydrogen at partial pressures of O.810 atm. and 0.304 atm., respectively, when suitably plotted gave a straight line which was interpreted as belonging to the gaseous reaction alone, since the surface reaction, common to each series, was assumed, and reasonably so, to be independent of pressure. The velocity of the composite reaction was also shown experimentally to be increased by increasing the glass surface, to which it was stated to be proportional; and to be independent of the amount of sulphur present. Knowing the contribution of the gaseous reaction, data for the surface were deduced, and thus the temperature coefficient of each reaction was obtained: homogeneous 2.19, heterogeneous 1.48.