HYPOCHLOROUS ACID DECOMPOSITION IN THE PH 5-8 REGION

被引:143
作者
ADAM, LC [1 ]
FABIAN, I [1 ]
SUZUKI, K [1 ]
GORDON, G [1 ]
机构
[1] MIAMI UNIV,DEPT CHEM,OXFORD,OH 45056
关键词
D O I
10.1021/ic00043a011
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
The decomposition of hypochlorous acid in the neutral pH region was studied in 1.0 M NaClO4 from 15 to 50-degrees-C. The pK(a) of HOCl was also determined under these conditions. Hypochlorous acid has a maximum decomposition rate at pH 6.89. The decomposition is a third-order process. The values of DELTA-H(double dagger) and DELTA-S(double dagger) are 64.0 +/- 0.6 kJ/mol and -67 +/- 2 J/mol K, respectively. A mechanism for the decomposition of HOCl is proposed involving Cl2O.H2O and ClO2- as intermediates. Rate constants for the rate-determining steps of the mechanism are presented. Above pH 6, the rate-determining step is proposed to be as follows: OCl- + Cl2O.H2O --> HCl2O2- + HOCl. Below pH 6, this process is proposed to be in competition with a parallel pathway: HOCl + Cl2O-H2O --> H2Cl2O2 + HOCl. The proposed mechanism was tested by mathematical simulation of the experimental data using the GEAR algorithm. The simulation gives additional support for the proposed mechanism.
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页码:3534 / 3541
页数:8
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