https://doi.org/10.1351/goldbook.C01210
A reaction that involves more than one Reactions occurring in parallel, such as: are called Reactions occurring in forward and reverse directions are called Reactions occurring in Reactions are said to exhibit feedback if a substance formed in one step affects the rate of a previous step. For example, in the scheme: The intermediate Y may catalyse the reaction (
elementary reaction
is said to occur by a composite
mechanism. The terms complex mechanism
, indirect
mechanism, and step-wise
mechanism are also commonly used. There are two main kinds of evidence for a composite
mechanism: - The kinetic equation for the reaction does not correspond to its stoichiometry.
- There is experimental evidence, direct or indirect, for intermediates of such a nature that it is necessary to conclude that more than one elementary reactionis involved.
composite
mechanisms, for example: parallel reactions
or simultaneous reactions
. When there are simultaneous reactions
there is sometimes competition
, as in the scheme: where B and C compete with one another for A.opposing reactions
: sequence
, such as are known as consecutive reactions
.positive feedback
) or it may inhibit it (negative feedback).Chain reactions