The kinetics of the decomposition, in carbon tetrachloride solution, of ozone and of ozone-chlorine mixtures

It was recently found that the decomposition of chlorine monoxide takes place at the same rate in solution in carbon tetrachloride as in the gaseous state. Under both conditions the reaction occurs in consecutive stages, each bimolecular. The rate of the unimolecular decomposition of nitrogen pentoxide is also uninfluenced by carbon tetrachloride. Thus this solvent appears to be established as a “normal” medium for reactions of varying kinetic type. The interest of this lies in the fact that with reactions that cannot be measured in the gaseous state at all, the rate in carbon tetrachloride can be taken as the rate which the reaction would have in the absence of a medium, and the influence of any given solvent can at once be recognised as accelerating or retarding. In this way it may be possible to obtain a deeper understanding of the effect of solvents on the rates of chemical reactions. In the meantime it is desirable to make as many direct measurements as possible on reactions which can be measured both in the gas and in solution. This paper deals with the decomposition of ozone, and with the catalytic decomposition of ozone by chlorine, both in carbon tetrachloride solution. The gaseous reactions have both been fairly extensively studied. The catalytic reaction takes place in the dark in a complex series of changes, and has even been said, though on somewhat uncertain evidence, to involve chains of 104 cycles; nevertheless, the rate in carbon tetrachloride solution is the same as the rate in the gas phase within a factor of 1·5 to 1. Further, in the corresponding photochemical reaction the number of molecules of ozone decomposed for each quantum of light is 2 both in the gas and in solution. Thus we have evidence that the several different chemical changes involved in these reactions are all almost unaffected by the carbon tetrachloride.