Chemistry · Year 12

Active learning ideas

Thermodynamics and Equilibrium

Active learning helps Year 12 students grasp thermodynamics by making abstract concepts concrete through calculations and simulations. Working with ΔG, ΔH, and ΔS in pairs or groups lets students test predictions and see how temperature shifts affect equilibrium in real time.

• ACARA Content Descriptions
• ACSCH097

• 20–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Concept Mapping
• 30 min · Pairs

Pairs Calculation: ΔG at Varying Temperatures

Provide data tables with ΔH and ΔS values for five reactions. Pairs calculate ΔG at 298K, 373K, and 473K, then plot graphs to predict spontaneity changes. Discuss which reactions favor products at high T.

Explain the relationship between Gibbs Free Energy and the equilibrium constant.

Facilitation Tip

During the Pairs Calculation activity, circulate and ask pairs to explain their sign choices for ΔH, ΔS, and T in their ΔG calculations before they compute the final value.

What to look for

Provide students with a set of reactions and their corresponding ΔH, ΔS, and T values. Ask them to calculate ΔG for each and classify the reaction as spontaneous, non-spontaneous, or at equilibrium under those conditions.

• Understand
• Analyze
• Create
• Self-Awareness
• Self-Management

Activity 02

• Concept Mapping
• 45 min · Small Groups

Small Groups: Equilibrium Shift Simulation

Use cobalt chloride solutions in test tubes; heat and cool to show color changes representing equilibrium shifts. Groups measure absorbance with colorimeters at different temperatures, calculate approximate K, and link to ΔG trends.

Predict the spontaneity of a reaction based on changes in enthalpy and entropy.

Facilitation Tip

In the Small Groups Simulation, assign each group a different reaction so their observations can be compared during the whole-class discussion afterward.

What to look for

Pose the question: 'How can a reaction that is endothermic (positive ΔH) become spontaneous at high temperatures?' Guide students to discuss the role of the TΔS term in the Gibbs Free Energy equation and relate it to entropy changes.

• Understand
• Analyze
• Create
• Self-Awareness
• Self-Management

Activity 03

• Concept Mapping
• 40 min · Whole Class

Whole Class: Jigsaw on Spontaneity Factors

Assign expert groups to enthalpy-dominant, entropy-dominant, or temperature effects. Experts teach home groups using reaction examples, then home groups solve mixed problems collaboratively.

Analyze how temperature influences the spontaneity and equilibrium position of a reaction.

Facilitation Tip

For the Jigsaw on Spontaneity Factors, provide a template with clear questions to guide group discussions so all students contribute and stay on task.

What to look for

Ask students to write down the equation linking ΔG° and K. Then, have them predict whether a reaction with a large positive K value would have a positive or negative ΔG° and explain their reasoning.

• Understand
• Analyze
• Create
• Self-Awareness
• Self-Management

Activity 04

• Concept Mapping
• 20 min · Individual

Individual: Reaction Feasibility Cards

Distribute cards with ΔH, ΔS, T values. Students sort into spontaneous/non-spontaneous categories, justify with ΔG calculations, then pair-share to verify.

Explain the relationship between Gibbs Free Energy and the equilibrium constant.

What to look for

Provide students with a set of reactions and their corresponding ΔH, ΔS, and T values. Ask them to calculate ΔG for each and classify the reaction as spontaneous, non-spontaneous, or at equilibrium under those conditions.

• Understand
• Analyze
• Create
• Self-Awareness
• Self-Management

A few notes on teaching this unit

Teach thermodynamics by focusing on the Gibbs Free Energy equation as a decision-making tool rather than just a formula. Use temperature as a variable to help students see patterns in spontaneity, not as a standalone factor. Avoid overemphasizing memorization of reaction types; instead, build intuition through repeated calculation and scenario testing.

Students will confidently calculate ΔG and explain how it relates to spontaneity and equilibrium position. They will also articulate why temperature changes shift equilibrium differently for endothermic versus exothermic reactions, using Gibbs Free Energy as a predictive tool.

---

Watch Out for These Misconceptions

• During the Pairs Calculation activity, watch for students who equate spontaneity with reaction speed. Redirect them by asking, 'If diamond slowly turns into graphite at room temperature, is this reaction spontaneous? What does that tell you about speed versus thermodynamic favorability?'

  During the Equilibrium Shift Simulation, students may think ΔG is always zero at equilibrium. Have them adjust concentrations to see ΔG values change while equilibrium is maintained, then ask, 'What stays constant at equilibrium, and what changes?'

• During the Small Groups Simulation, students might assume temperature always increases spontaneity. Provide a reaction with negative ΔH and negative ΔS, and ask groups to calculate ΔG at 298 K and 500 K to observe the effect.

  During the Jigsaw on Spontaneity Factors, address the idea that temperature always promotes spontaneity by having groups compare their cases and present the conditions under which high temperature reduces spontaneity.

---

Methods used in this brief

• Concept Mapping