The last reaction (k4)
occurs so fast that it scavenges any N20 as rapidly
as it is formed, and has no effect on the overall rate of the process. In
effect, N2 is produced as fast as N20
appears, so
In a series of reactions, the slowest one has the
greatest influence on reaction rates. To invoke a painful analogy, if
it takes ten days to to get a certified letter from Los Angeles to the
White House, then rushing to get it into the one o'clock mail instead
of the three o'clock will make little difference in the long run.
Formation
of HBr
The rather horrendous rate law for the HBr
reaction,
arises because the true process is a chain
reaction that involves first the dissociation of Br2
molecules into atoms, then the reaction of atoms with other H2
and Br2 molecules:
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