KBr ACTION ON THE RATE OF H_2O_2 DECOMPOSITION IN ALKALINE MEDIUM

摘要

The action of KBr in the concentration range 0/8x10~(-2) mol dm~(-3) on the H_2O_2 decomposition rate (R) in alkaline medium has been studied by gasometric method.It has been established that at [KBr]_0=0.4x10~(-2) mol dm~(-3) the reaction R has minimum value.It is maximum at [KBr]_0=4xl0~(-2) mol dm~(-3).The established regularities are explained assuming that KBr plays double role.At [KBr]_0<= 0.4x10~(-2) mol dm~(-3) in a larger extent its action as strong electrolyte is being revealed which results in the increase of the medium ionic strength (I).Its increase results in the decrease of all dissociation processes,which concerns in particular the hydrogen peroxide's dimers which are in concentrated water solutions.This hypothesis is confirmed studying the R dependence on Na_2SO_4 and NaCl concentrations which are strong electrolytes as KBr,but they are indifferent with respect to HOOH.The R enhance when 0.4x10~(-2)<= [KBr]_0<= 4x10~(-2) mol dm~(-3) is explained on the ground of Br~- specific catalytic action.This hypothesis is verified by two independent methods:studying the KJ action on R and R dependence on temperature which allowed to determine the reaction activation energy in three cases:[KBr]_0=0 (i),0.4x10~(-2) mol dm~(-3) (ii),and 4x10~(-2) mol dm~(-3) (iii).