Safety boundary
Use paper-token models, supplied calculations, and simulations only. No unsupervised chemical reactions are required.
Explicit chemistry instruction
Limiting-reactant analysis turns a balanced equation into a resource-allocation model: one input becomes the binding constraint.
Theoretical yield is the model prediction; actual yield is evidence; percent yield compares the two.
A strong conclusion explains both the quantitative result and why real systems may depart from the ideal stoichiometric prediction.
Vocabulary: constraint; theoretical yield; actual yield; percent yield; model limit.
Worked example
A reaction can be perfectly balanced on paper yet produce less than theoretical yield because the balanced equation does not include every real-world loss pathway.
Guided question
Write a CER explaining why one reactant limits product and why actual yield can be lower than predicted.
Independent work
- Solve one full limiting/yield problem.
- Write a CER using quantitative evidence.
- Record one corrected misconception.
- Identify one uncertainty source.
Spiral retrieval bridge
- From Week 15: use coefficients as mole ratios.
- From Week 14: connect balanced equations with conservation of atoms.
- From Week 12: distinguish amount of solute from concentration.
Misconception check
Stoichiometric balance does not imply 100% experimental yield.
Formative check
What is the conceptual difference between limiting reactant and percent yield?
Reveal response
The limiting reactant sets the maximum product; percent yield compares measured product with that maximum.
Mentor evidence conference
Ask Archaemenes to audit the limiting-reactant logic, conversion chain, and evidence interpretation.
Teacher guidance
Foundation: Use a CER frame.
Core: Integrate prediction and evidence.
Extended: Evaluate alternate explanations for yield loss.