Chemistry · 9th Grade

Active learning ideas

Enthalpy and Calorimetry

Active learning is essential for grasping enthalpy and calorimetry because these concepts move from abstract definitions to tangible heat transfer. Hands-on experiences, like the Simple Calorimetry Lab, allow students to directly observe and measure heat changes, making the abstract concept of enthalpy more concrete and relatable.

• Common Core State Standards
• HS-PS1-4
• STD.CCSS.MATH.CONTENT.HSN.Q.A.1

• 30–60 min
• Pairs → Whole Class
• 3 activities

Activity 01

• Inquiry Circle
• 60 min · Small Groups

Format Name: Simple Calorimetry Lab

Students measure the temperature change when dissolving a salt in water or mixing two solutions of different temperatures. They then use the collected data to calculate the heat absorbed or released by the water and, by extension, the enthalpy change of the process.

Explain the concept of enthalpy change (ΔH) for chemical reactions.

Facilitation Tip

During the Simple Calorimetry Lab, guide students to meticulously record initial and final temperatures, emphasizing precise measurements for accurate heat calculations.

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

Activity 02

• Inquiry Circle
• 45 min · Whole Class

Format Name: Hess's Law Demonstration

Demonstrate Hess's Law by measuring the enthalpy change of a reaction that can be carried out in multiple steps. Students can then calculate the enthalpy change for the overall reaction by summing the enthalpy changes of the individual steps, comparing it to direct measurement.

Construct calculations to determine heat transfer using calorimetry data.

Facilitation Tip

When demonstrating Hess's Law, ensure students understand that the total enthalpy change is independent of the path taken, and that intermediate measurements are key to verifying this principle.

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

Activity 03

• Inquiry Circle
• 30 min · Pairs

Format Name: Bond Energy Calculation Practice

Provide students with a list of bond energies and a chemical equation. Students work in pairs to calculate the theoretical enthalpy change of the reaction by summing the energy required to break bonds and subtracting the energy released when forming new bonds.

Analyze the relationship between bond breaking/forming and enthalpy changes.

Facilitation Tip

During Bond Energy Calculation Practice, encourage pairs to discuss how bond strengths influence the overall energy released or absorbed in a reaction, reinforcing the relationship between bond energies and enthalpy change.

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

A few notes on teaching this unit

Teachers should approach enthalpy and calorimetry by first establishing the difference between heat and temperature, then moving to experimental measurement. Using Experiential Learning for calorimetry makes the abstract concept of heat transfer tangible, while guided practice with Bond Energy Calculations solidifies the theoretical underpinnings.

Students will successfully measure temperature changes in controlled experiments and use these data to calculate enthalpy changes. They will be able to differentiate between exothermic and endothermic processes and explain the energy changes involved in bond breaking and formation.

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Watch Out for These Misconceptions

• During the Simple Calorimetry Lab, watch for students assuming all reactions release heat and thus expect a temperature increase.

  Redirect students by pointing to their data if they observe a temperature decrease, prompting them to consider endothermic processes and the absorption of heat from the surroundings.

• During the Simple Calorimetry Lab, students may equate the measured temperature change directly with the enthalpy change of the reaction.

  Guide students back to their calculations, asking them to identify where the heat absorbed or released by the solution (q) is determined, and how this relates to the enthalpy change (ΔH) using the mass and specific heat capacity of the solvent.

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Methods used in this brief

• Inquiry Circle