The kinetics of some gas phase reactions of chlorine monofluoride and chlorine trifluoride

Abstract

Information concerning the rates of four gas phase reactions involving chlorine monofluoride and chlorine trifluoride have been obtained. (I) It is found that radioactive chlorine does not exchange at a measurable rate between Cl 2 and ClF 3 in the liquid phase at −80°C or in the gas phase up to 165°C. (II) The reaction of Cl 2 with ClF 3 to form ClF appears to be essentially homogeneous in the gas phase and proceeds at a conveniently measurable rate in the temperature range 180–250°C. It follows a second-order rate expression within experimental error with activation energy 20·18 kcal mole −1 and activation entropy −12·3 e.u. A rate determining step involving a bimolecular collision leading to a molecular complex accounts satisfactorily for the data. (III) The exchange of radioactive chlorine between ClF 3 and tagged ClF has been followed in the temperature range 203–245°C. The exchange appears to be homogeneous with rate proportional to the product of the square roots of the reactant concentrations and activation energy 15·9 ± 1·0 kcal/mole. No simple mechanism was found consistent with our data. (IV) The rate of exchange of radioactive chlorine between Cl 2 and ClF was found, in a preliminary investigation, to be 50 per cent complete in less than an hour at room temperature.