2312. MOORE, W. J. Parabolic Oxidation Rates of Metals. Jour. Chem. Phys., vol. 18, 1950, p. 231; Chem. Abs., vol. 44, 1950, p. 5686.
Constants, ∆H‡, ∆S‡, ∆F‡, of the transition-state theory (abs. 1283) for the oxidation of Al, Fe, Zr, Ti, Ni, Cu, Co, Zn, and Be are compared. Except for Be, there is little variation in the ∆F‡ values; hence reactions with high ∆H‡ also have high ∆S‡. A schematic diagram of the potential-energy barriers for vacancy formation and diffusion shows that, for equal diffusion barriers, the higher the heat of adsorption, the lower the effective ∆H‡. Since a high heat of adsorption implies an immobile adsorbed film, it may also be associated with a large negative ∆S of adsorption; this may help explain the approximate constancy of ∆F.
MORCOM, A. R. See abs. 1629.
MOREAU, J. See abs. 190.