Answer:
A reaction mechanism is a series of elementary reactions that describe how an overall reaction occurs and explain the experimentally determined rate law.
Step-by-step explanation:
A reaction machanism is a succession of steps to go from the reactants to the products of a reaction.
Each of this steps is a different elementary reaction and produces an intermediary product. This intermediaries not always can be seen in real life due to the high rate of reaction of following steps.
This intermediary reactions where created to explain the experimental determined rate law of some reactions, that doesn't fit in a one-step reaction.
In conclusion we can say that: A reaction mechanism is a series of elementary reactions that describe how an overall reaction occurs and explain the experimentally determined rate law