The Reaction of Chlorine with Hydrogen

VOL. 18, 1932 CHEMISTRY: RODEBUSHANDKLINGELHOEFER

531

The authors are indebted to Professor Charles Palache of Harvard University, Professor D. Jerome Fischer of the University of Chicago and Dr. T. L. Tanton of the Department of Mines of the Canadian Geological Survey, through whose efforts the rocks used in this investigation were obtained. 1 Rayleigh, Proc. Roy. Soc., 80, 575 (1908). 2Rayleigh, Nature, 123, 607 (1929). 3 See Harkins, P. R., 38, 1270 (1931).

'Paneth, Z. Physik. Chem., 134, 353 (1928).

TIIE REACTION OF CHLORINE WITH HYDROGEN BY W. H. RODEBUSH AND W. C. KLINGELHOEFER CHEMIcAL LABORATORY, UNIVERSITY OF ILLINOIS Communicated June 16, 1932

The authors have developed the technique of preparing atomic chlorine in the laboratory. The reaction,

Cl + H2

=

HCl + H

has been investigated at low pressures. This reaction initiates chains which produce at least ten molecules of hydrogen chloride at 1 mm. pressure. Assuming the reaction, H + C12 = HCI + Cl to be rapid it has been found that the chlorine atom has a reaction probability of the order of 10-5 per collision with the hydrogen molecule. From the temperature coefficient of the reaction probability it is possible to calculate a heat of activation of 5500 calories. This is much larger than the activation energy assumed by Rollefson and Lindquist' but much smaller than the value calculated by Eyring.2 Oxygen as might be expected does not affect the reaction at low pressures. The reaction was ordinarily carried out with very dry gases but the addition of water had no effect. This confirms the work of Bodenstein3 and contradicts the work of Coehn and Jung.4 The Nernst chain appears to account fully for the reaction mechanism at low pressures. The details of this research will be published elsewhere. 1 J. Am. Chem. Soc., 52, 2793 (1930). 2 J. Am. Chem. Soc., 53, 2537 (1931). 3Private communication.

4Zeit. physik. Chemie, 110, 705 (1924).