Chemistry Year 11 - Module 2 - Lesson 13
Limiting Reagents & Theoretical Yield
1. Key Ideas
Most real reactions don't have reactants in perfect stoichiometric proportions — one runs out first and stops the reaction. Identifying which reactant is the limiting reagent, and calculating the maximum possible yield, are among the most tested skills in HSC Chemistry.
- Limiting reagent (LR) — the reactant that runs out first
- Why the reaction stops when the LR is consumed
2. Success Criteria
By the end, you should be able to:
- Limiting reagent (LR) — the reactant that runs out first
- Excess reagent — the reactant remaining when reaction stops
- Theoretical yield — maximum product from LR
3. Key Terms
4. Activity: Build the Lesson Map
Use the lesson to complete the table. Keep answers brief but specific.
| Prompt | Your answer |
|---|---|
| Main concept | |
| Important example | |
| Common mistake to avoid | |
| How this links to the next lesson |
5. Short Answer Questions
1. Explain this lesson goal in your own words: "Limiting reagent (LR) — the reactant that runs out first". Use one specific example from the lesson.
2. Apply this idea to a new example: "Excess reagent — the reactant remaining when reaction stops". Show your reasoning clearly.
3. Analyse why this idea matters for understanding Limiting Reagents & Theoretical Yield: "Theoretical yield — maximum product from LR".
6. Extend: Apply the Idea
A student gives a memorised answer about Limiting Reagents & Theoretical Yield but does not use evidence or reasoning.
Improve the answer by writing a stronger response that uses accurate terminology, a relevant example and a clear explanation.
7. Multiple Choice
1. What is the best first step when answering a question about Limiting Reagents & Theoretical Yield?
A. Identify the key concept being tested
B. Write every fact from memory
C. Ignore the command word
D. Skip examples and evidence
2. Which answer would show stronger understanding of Limiting Reagents & Theoretical Yield?
A. An answer with accurate terms and reasoning
B. A copied definition only
C. A single-word response
D. An answer with no example
3. What should you do if a question asks you to explain?
A. Link the idea to a reason or cause
B. List unrelated facts
C. Only draw a diagram
D. Write the shortest possible answer
8. Success Criteria Proof
Finish with evidence that you can do each success criterion.