Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Chemistry
Lesson Topic: Calculate the enthalpy change of a reaction using bond energies
Learning Objective/s:
  • Describe the concept of enthalpy change and its sign convention.
  • Apply bond‑energy values to calculate ΔH for a balanced chemical reaction.
  • Interpret the calculated ΔH to classify reactions as exothermic or endothermic.
  • Identify common errors in bond‑energy calculations and correct them.
Materials Needed:
  • Projector or interactive whiteboard
  • Chemistry textbook or teacher guide on bond energies
  • Worksheet with practice reactions
  • Bond‑energy table handout
  • Calculator (or spreadsheet)
  • Whiteboard markers and erasers
 Introduction:
Begin with a quick demonstration of a candle burning to illustrate heat release, then ask students to recall what enthalpy represents and how it relates to reaction heat. Review the definition of bond energy and the ΔH sign convention. Explain that by the end of the lesson they will be able to compute ΔH using bond‑energy data and justify the reaction’s thermicity.
Lesson Structure:
  1. Do‑now (5'): Students complete a short quiz on exothermic vs. endothermic reactions.
  2. Mini‑lecture (10'): Review enthalpy, bond energy, and the formula ΔH = Σ broken – Σ formed with board examples.
  3. Guided practice (15'): Work through the methane combustion example together, filling a table of broken and formed bonds.
  4. Independent practice (15'): Students calculate ΔH for two practice reactions using the provided bond‑energy table.
  5. Peer check (5'): Pairs exchange answers and discuss discrepancies while the teacher circulates.
  6. Error analysis (5'): Highlight common mistakes and have students correct a deliberately flawed calculation.
  7. Quick recap (5'): Summarise key steps and answer final questions.
Conclusion:
Summarise the step‑by‑step procedure for using bond energies to find ΔH and remind students how the sign indicates reaction thermicity. Collect an exit ticket where each pupil writes the ΔH for a given reaction and states whether it is exothermic or endothermic. Assign homework to complete additional ΔH calculations from the textbook and to reflect on the limitations of the bond‑energy method.