A reaction mechanism is the step-by-step sequence of elementary reactions by which reactants are converted into products.
Key points:
- Explains how a reaction occurs: Shows the pathway at the molecular level.
- Made of elementary steps: Each step involves simple collisions or transformations of molecules.
- Rate-determining step: The slowest step in the mechanism controls the overall reaction rate.
- Helps understand kinetics: The mechanism explains why the rate law has a particular form.
Example: For a reaction A + B → C, the mechanism might involve:
- Step 1: A + B → intermediate (slow)
- Step 2: Intermediate → C (fast)