The Elovich equation dg/di = ae~at where g is the amount chemisorbed at time t, and a and a are constants, is shown to be applicable to a large body of rate of chemisorption data. The significance of a and a is examined and shown to imply that the prime function of the gas, initially, is the production of surface sites which, over the course of the slow adsorption, decay at a bimolecular rate. The rate of slow chemisorption is governed solely by the availability of sites. Parallels to the proposed schemes are found in kinetics of luminescence and photoconductivity of solids.

Using the time-dependent variational principle with a group theoretical coherent state defining the wave functions for electrons and nuclei, a system of coupled, first-order, nonlinear differential equations is obtained for a general molecular system. The equations form a classical Hamiltonian system within a generalized phase space that allows a systematic time-dependent study of molecular processes. The approach is general and provides a computational framework for a variety of properties such as transition and excitation probabilities in atomic and molecular collisions, and molecular spectra such as vibrational spectra with anharmonicities. The basic approximation corresponding to the choice of a single determinantal wave function for the electrons and classical nuclei is analyzed. Illustrative applications to the p+H collision process and to vibrations of the H2O molecule exhibit good agreement with experiment and with other theoretical work.

In attempts during recent years to isolate data for unimolecular reactions the decomposition of various organic halides, ethers, azo compounds, amines, and nitrites has been studied kinetically, and though superficial results would suggest that in most cases a net reaction of the first order was occurring, extremely few are so free from secondary changes that the results may be accepted unequivocally. The multiplication of such attempts is thus justified. No nitro compounds have so far been studied. The simplest, nitromethane, was therefore chosen.The apparatus and method used for the study were identical with those used previously by Taylor (3) in similar work, and involved the determination of the rate of pressure change of the reactant with time. To prevent condensation of the nitromethane vapor the apparatus outside the furnace was maintained at about 80°C. throughout the work. The nitromethane used was carefully fractionated from a Kahlbaum sample, the fraction boiling between 100.5 and 101°C. being collected. Temperatures from 390 to 420°C. were found to yield a convenient velocity of decomposition. The percentage increase in pressure during reaction was found to be 130, independent of temperature and pressure, as is shown in table 1.Data of a typical experiment are given in table 2 showing the observed pressure increases occurring at the specified times at 420°C. with an initial pressure of 198 mm. of nitromethane.The complete data are presented in table 3 in the form of fractional lives calculated as the times necessary for 25, 50, and 75 per cent of the total pressure increase to occur.

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