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Limiting Reagent and Percent Yield Calculator

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About This MicroSim

Students supply the mass of two reactants, choose a balanced equation, and optionally enter an actual product yield. The left panel hosts the mass inputs, reaction selector, and buttons. The right panel automatically calculates moles, identifies the limiting reagent, reports theoretical yield, and animates a percent-yield gauge. A bar chart compares moles-per-coefficient for each reactant, and a collapsible "Show Work" section reveals every intermediate calculation.

How to Use

  1. Enter the mass of Reactant A, Reactant B, and the Actual Yield of the product you recovered in lab.
  2. Choose a reaction from the dropdown list; the MicroSim tracks the product listed in parentheses.
  3. Press Calculate to run the stoichiometric analysis. The text panel explains which reagent limits the reaction and why.
  4. Toggle Show Work to display each calculation step (mole conversions, normalized ratios, theoretical yield, percent yield).
  5. Use Reset to restore the default ammonia synthesis example.

Classroom Ideas

  • Station Lab Companion: Place this MicroSim at a station so students can verify their limiting-reactant predictions before proceeding in a wet lab.
  • Percent-Yield Clinics: Have groups intentionally choose masses that produce low, medium, or high percent yields and explain the difference.
  • What-If Scenarios: Ask learners to double one reactant and predict how the bars, limiting reagent, and theoretical yield will change before pressing Calculate.
  • Error Spotting: Present a scenario with a percent yield over 100% and prompt students to hypothesize the experimental mistake.

Lesson Plan

Grade Level

Grades 10–12 (AP Chemistry Unit 4) and introductory college general chemistry

Duration

15 minutes for guided practice or a post-lab analysis task

Prerequisites

  • Converting between mass and moles
  • Using stoichiometric coefficients to determine limiting reagents
  • Understanding the definitions of theoretical yield, actual yield, and percent yield

Activities

  1. Demo (3 min): Instruct students on how the MicroSim highlights the limiting reagent using the bar chart.
  2. Practice Set (8 min): Learners try three different reaction/mass combinations and record limiting reagent, theoretical yield, and percent yield.
  3. Reflection (4 min): Students write a brief explanation of why the smallest moles-per-coefficient value must limit the reaction in all scenarios.

Assessment

  • Quick exit problem: Provide masses for Fe and S and ask students to submit a screenshot of the MicroSim output with percent yield highlighted.
  • Homework extension: Students copy the "Show Work" output and annotate each step with the rule or relationship used.

References

  1. Tro, N. J. Chemistry: A Molecular Approach, 6th ed., Pearson, 2024 — Limiting reactant and yield calculations.
  2. Zumdahl & Zumdahl. Chemistry, 11th ed., Cengage, 2023 — Stoichiometry and percent-yield problem-solving strategies.