Chemistry · Year 12

Active learning ideas

Introduction to Dynamic Equilibrium

Active learning works for dynamic equilibrium because students often assume reactions finish completely, and hands-on experiences reveal that reactions continue in both directions. By manipulating physical systems and observing real-time changes, students confront their misconceptions directly and build accurate mental models of reversible processes.

• ACARA Content Descriptions
• ACSCH094

• 15–40 min
• Pairs → Whole Class
• 3 activities

Activity 01

• Simulation Game
• 20 min · Small Groups

Simulation Game: The Water Transfer Race

Two students transfer water between two large beakers using different sized measuring cylinders. They start with one full and one empty beaker, continuing until the volume in each stays constant despite ongoing transfers, demonstrating equal rates.

Explain the molecular processes occurring in a system at dynamic equilibrium.

Facilitation Tip

During the Water Transfer Race, circulate and ask groups to predict what will happen to the water levels if one cup is slightly larger than the other before they start pouring.

What to look for

Present students with a diagram of particles in a container. Ask them to draw arrows indicating forward and reverse reactions. Then, ask them to write one sentence comparing the rates of these reactions when the system is at equilibrium.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

Activity 02

• Think-Pair-Share
• 15 min · Pairs

Think-Pair-Share: Molecular Snapshots

Students view three diagrams of a reaction at different time intervals. They must identify which represents equilibrium by counting reactant and product particles and then explain their reasoning to a partner based on the definition of a closed system.

Compare the rates of forward and reverse reactions at equilibrium.

Facilitation Tip

For Molecular Snapshots, provide a timer for the pair discussion phase to keep the exchange focused and ensure all students contribute.

What to look for

Pose the question: 'If a system is at dynamic equilibrium, does this mean the reaction has stopped?' Facilitate a class discussion where students must use the terms 'forward reaction rate' and 'reverse reaction rate' to justify their answers.

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

Activity 03

• Inquiry Circle
• 40 min · Small Groups

Inquiry Circle: Cobalt(II) Chloride Shift

Groups manipulate the temperature of a cobalt chloride solution in a sealed tube. They record colour changes and collaboratively map these observations to the movement of particles at the molecular level to explain the dynamic nature of the shift.

Analyze experimental evidence that supports the dynamic nature of chemical equilibrium.

Facilitation Tip

In the Cobalt(II) Chloride Shift, have students record initial observations before adding water to create a baseline for comparison when color changes occur.

What to look for

Provide students with a concentration-time graph for a reversible reaction. Ask them to circle the region where dynamic equilibrium is established and explain in one sentence what is happening to the rates of the forward and reverse reactions in that region.

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

A few notes on teaching this unit

Teachers should start with macroscopic models before moving to abstract graphs or equations, as students need to see equilibrium in action before connecting it to particle diagrams. Avoid rushing to Le Chatelier’s principle; instead, solidify the concept of dynamic equilibrium first. Research suggests using multiple representations (simulations, physical models, graphs) helps students transfer understanding across contexts.

Successful learning looks like students explaining that equilibrium depends on equal reaction rates, not equal concentrations, and using evidence from simulations or investigations to justify their reasoning. They should also recognize that equilibrium does not mean the reaction has stopped but that changes occur continuously at the molecular level.

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Watch Out for These Misconceptions

• During the Simulation: The Water Transfer Race, watch for students assuming the volumes in both cups will become equal at equilibrium.

  Redirect students by asking them to measure the final volumes and discuss why the levels stabilize at different heights even though the rates of water transfer are equal. Emphasize that equilibrium depends on rates, not amounts.

• During the Collaborative Investigation: Cobalt(II) Chloride Shift, watch for students interpreting the color change as the reaction stopping.

  Use the physical change to prompt students to explain that the system is still active microscopically. Ask them to imagine the pink and blue ions continuously interchanging and relate this to the idea of dynamic equilibrium.

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Methods used in this brief

• Simulation Game
• Think-Pair-Share
• Inquiry Circle