Lesson Plan

• Describe entropy and its statistical basis.
• Explain Gibbs free energy and its relation to spontaneity.
• Calculate ΔS°, ΔH°, and ΔG° for a given reaction using tabulated data.
• Predict reaction feasibility at different temperatures using ΔG = ΔH – TΔS.
• Evaluate kinetic factors that may affect observed reaction rates.

• Projector and screen for slides
• Whiteboard and markers
• Printed worksheet with entropy and Gibbs free energy problems
• Periodic table handouts
• Calculator or computer spreadsheet
• Data tables of ΔH_f° and S° values

Imagine a firecracker exploding—why does it happen spontaneously? Review the concepts of enthalpy change and spontaneity from the previous lesson. By the end of class you will be able to compute ΔG and decide whether a reaction is thermodynamically favorable.

1. Do‑now (5'): Quick quiz on ΔH and entropy definitions.
2. Mini‑lecture (15'): Explain entropy, Boltzmann’s equation, the second law, and introduce Gibbs free energy.
3. Guided practice (20'): Calculate ΔS° and ΔG° for methane combustion using the provided data tables.
4. Interactive activity (10'): Small groups assess feasibility of several reactions at different temperatures using ΔG = ΔH – TΔS.
5. Kinetics discussion (5'): Brief overview of activation energy and the role of catalysts.
6. Check for understanding (5'): Exit ticket – state the sign of ΔG for a given reaction and justify.

We reviewed how entropy and Gibbs free energy determine reaction spontaneity and saw how temperature can flip the sign of ΔG. Students submit their exit tickets, summarising the key criteria for feasibility. For homework, complete the worksheet on predicting reaction spontaneity at 350 K and 500 K.