Advanced Chemical Principles and Molecular Dynamics · 6th Year

Active learning ideas

Catalysis

Introduce the fascinating world of chemical 'matchmakers', catalysts, which speed up reactions without getting involved themselves.

• NCCA Curriculum Specifications
• Leaving Certificate Chemistry Syllabus: Physical Chemistry - Rates of Reaction

• 15–30 min
• Pairs → Whole Class
• 3 activities

Activity 01

• Simulation Game
• 15 min · Whole Class

The 'Elephant's Toothpaste' Demonstration

Demonstrate the rapid decomposition of concentrated hydrogen peroxide using potassium iodide or manganese(IV) oxide as a catalyst. The addition of washing-up liquid and food colouring creates a dramatic and memorable eruption of foam, visually representing a massively increased reaction rate.

Explain how a catalyst increases the rate of a reaction.

Facilitation Tip

Ensure you perform this as a teacher demonstration in a fume hood or well-ventilated area with appropriate safety precautions.

What to look for

Ask students to draw a potential energy profile for an exothermic reaction on mini-whiteboards, then instruct them to add a line showing the effect of a catalyst. This allows for a quick check of understanding of activation energy.

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

Activity 02

• Simulation Game
• 30 min · Pairs

Investigating Enzyme Action

Students use a piece of potato or liver (containing the enzyme catalase) to catalyse the breakdown of hydrogen peroxide. They can observe the rate of bubble production and compare it to an uncatalysed reaction, introducing the concept of biological catalysts.

Compare homogeneous and heterogeneous catalysis with examples.

Facilitation Tip

Encourage students to consider variables like temperature or pH to see how they affect the enzyme's catalytic activity.

What to look for

Set a past Leaving Certificate exam question on catalysis that requires students to define terms, compare catalyst types, and apply their knowledge to an unfamiliar industrial process.

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

Activity 03

• Simulation Game
• 25 min · Small Groups

Homogeneous Catalysis Colour Change

Students observe the reaction between potassium sodium tartrate (Rochelle salt) and hydrogen peroxide. The reaction is slow at room temperature but is sped up significantly by adding a small amount of cobalt(II) chloride solution, which results in a visible colour change as the catalyst participates in the reaction mechanism.

Identify the features of a catalytic converter in a car.

Facilitation Tip

Use a water bath to gently warm the reactants to show the initial slow rate before adding the catalyst.

What to look for

Provide students with a 'traffic light' checklist of the learning objectives. They colour each objective red, amber, or green to indicate their level of confidence before beginning revision.

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

A few notes on teaching this unit

Begin with a visually striking demonstration to grab attention and illustrate a catalyst's power. Follow this with clear diagrams to explain the abstract concept of activation energy pathways. Finally, ground the theory in tangible applications like car exhausts and fertiliser production to make the learning stick.

Your students will be able to explain how catalysts lower the energy barrier for reactions and can classify them based on real-world industrial and environmental examples.

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Watch Out for These Misconceptions

• Catalysts are used up during the reaction, just like reactants.

  A catalyst is chemically unchanged at the end of a reaction. While it may participate in intermediate steps, it is regenerated, so its mass remains constant.

• Catalysts make reactions happen that wouldn't happen otherwise.

  Catalysts only speed up reactions that are already thermodynamically feasible but slow. They do not initiate impossible reactions.

• A catalyst lowers the activation energy of the reactants themselves.

  A catalyst does not change the reactants. It provides a completely different reaction pathway, or mechanism, which has a lower activation energy.

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Methods used in this brief

• Simulation Game