Why is it often difficult to determine the actual pathway for a chemical reaction?

Each step in a mechanism will have a transition state. The transition states are often very difficult to identify and during a reaction the molecules exist in this state for essentially zero time. ... It is more of a theoretical idea for the configurations the chemical species must pass through during the reaction.

Explanation:

organisms are more likely to be more preserved in mud than sand because mud is moist and wet, while sand is very dry.