Safety boundary
Use energy-profile diagrams, supplied datasets, and approved simulations only. No catalyst/reaction demonstrations are required.
Explicit chemistry instruction
A reaction mechanism is a sequence of elementary steps whose sum reproduces the overall reaction.
Intermediates are formed in one step and consumed in another; they cancel from the overall equation.
The overall balanced equation does not usually reveal the detailed mechanism by itself.
Vocabulary: mechanism; elementary step; intermediate; overall reaction; pathway.
Worked example
Step 1 forms intermediate X; Step 2 consumes X. Adding the steps cancels X, leaving the overall reaction.
Guided question
Why can two mechanisms share the same overall balanced equation?
Independent work
- Identify intermediates in three mechanisms.
- Add elementary steps to recover an overall equation.
- Explain why mechanism evidence must come from kinetics or other observations.
Misconception check
A balanced equation is not automatically an elementary molecular event.
Formative check
What is an intermediate?
Reveal response
A species produced in one elementary step and consumed in a later step.
Mentor evidence conference
Ask Archaemenes to audit mechanism consistency, rate evidence, catalyst claims, and model limits.
Teacher guidance
Foundation: Use step-cancellation tables.
Core: Analyze multistep mechanisms.
Extended: Evaluate whether proposed steps reproduce both stoichiometry and kinetic evidence.