Ind. Eng. Chem. Res. 1995,34, 4235-4237
4235
Kinetics of Uncatalyzed Oxygen Evolution from Sodium Hypochlorite John A. Church? Colgate-Palmolive Company, 909 River Road, P.O. Box 1343, Piscataway, New Jersey 08855-1343
Previous kinetic data for the uncatalyzed evolution of oxygen from purified alkaline NaClO solutions have been extended to wider ranges of temperature and ionic strength, using a newlyreported unitized gas buret apparatus for determination of oxygen rates. Revised activation parameters for oxygen evolution are E , = 135300 - 4300 p f 2000 J g-mol-l (AIP = E , - RT) and AS* = 9.8 - 9.2p f 6.1 J K-lgmol-l, respectively, at 40-70 "C and ionic strength p = 1.5-5.5, valid also at 30 "C and p = 4.2-5.5. Uncatalyzed rate constants KO calculated from these parameters can be used with the previously-derived integrated rate equation to predict amounts of oxygen that would be evolved from purified NaClO solutions under arbitrary conditions within the range investigated.
Introduction Kinetics of the uncatalyzed and homogeneous Cu(I1)catalyzed decomposition of aqueous alkaline NaClO solutions were recently described from theoretical and experimental aspects, combining new and previouslypublished results (Church, 1994). The objective of the present work was to extend the limited data set for uncatalyzed oxygen evolution, thereby permitting derivation of improved values of the activation parameters for this relatively slow reaction (rate constant KO). This would allow better projections of oxygen generation rates for purified NaClO solutions, an important aspect in specifying storage conditions for commercial bleach. For determination of relatively low gas rates, e.g.,
