Releases or absorbs thermal energy by chemical processes

Standards Alignment

• MS-PS1-6 primary
  Undertake a design project to construct, test, and modify a device that either releases or absorbs thermal energy by chemical processes.*

Lesson Overview

In this Grade 6 physical science lesson, students engage in a hands-on design project where they construct, test, and modify devices that either release or absorb thermal energy through chemical reactions. The lesson emphasizes understanding chemical processes that involve thermal energy changes, such as dissolving ammonium chloride or calcium chloride, and applying iterative engineering design principles to optimize their devices. Students analyze data on temperature changes, control variables like substance type and concentration, and refine their designs based on test results to achieve desired thermal energy effects.

Learning Objectives

• Construct a device that uses a chemical process to release or absorb thermal energy.
• Test the device by measuring temperature changes over time and under varying conditions.
• Modify the device design based on test results to improve its performance in releasing or absorbing thermal energy.
• Explain how chemical reactions in their device cause thermal energy changes.
• Use scientific data to support claims about the device's thermal energy behavior.

Success Criteria

• Students build a working device that demonstrates thermal energy release or absorption through a chemical reaction.
• Students accurately measure and record temperature changes during testing.
• Students identify variables affecting thermal energy changes and control them during tests.
• Students propose and implement modifications to improve device performance based on test data.
• Students clearly explain the relationship between the chemical process and thermal energy changes using evidence.

Prerequisite Knowledge

Students should understand basic chemical reactions and the concept that chemical processes can release or absorb energy. They should be familiar with measuring temperature and controlling variables in an experiment.

Key Vocabulary

• Thermal energy
• Chemical reaction
• Exothermic
• Endothermic
• Design project
• Iteration
• Modification
• Concentration
• Temperature
• Testing

Materials and Resources

• Thermometers or temperature probes
• Substances such as ammonium chloride, calcium chloride, or other safe chemicals that release or absorb heat when dissolved
• Containers for mixing substances
• Measuring tools (spoons, cups)
• Data recording sheets or digital devices
• Materials for constructing device (e.g., plastic bottles, insulating materials)
• Safety equipment (gloves, goggles)

Teacher Preparation

• Review safety procedures for handling chemicals and conducting experiments.
• Prepare materials and chemicals for student use ensuring safe quantities.
• Set up a demonstration of a chemical reaction that releases or absorbs thermal energy.
• Prepare data recording templates for students.
• Familiarize with iterative design process and how to guide students in testing and modifying their devices.

Detailed Lesson Notes

Understanding Thermal Energy Changes in Chemical Reactions

Thermal energy is the energy that comes from the temperature of matter. Chemical reactions can either release thermal energy to the surroundings (exothermic reactions) or absorb thermal energy from the surroundings (endothermic reactions). For example, when ammonium chloride dissolves in water, it absorbs heat, causing the solution to feel cold. Conversely, dissolving calcium chloride releases heat, making the solution warm. Understanding these processes helps students grasp how chemical reactions affect energy transfer.

Designing a Device to Harness Thermal Energy Changes

Students will design a device that uses a chemical reaction to either release or absorb thermal energy. This involves selecting appropriate substances, deciding how to contain and mix them safely, and measuring the temperature changes produced. The design should consider controlling variables such as the amount of substance, concentration, and time of reaction to optimize thermal energy transfer. The device might be a simple insulated container where the reaction occurs and temperature can be monitored.

Testing and Measuring Thermal Energy Changes

Testing involves carefully mixing the chemicals in the device and measuring temperature changes over time using thermometers or probes. Students should record initial temperature, temperature at intervals, and final temperature to analyze the thermal energy change. Controlling variables like the amount of substance and environmental conditions is important to ensure reliable data. Observations should include whether the temperature rises or falls and by how much, indicating exothermic or endothermic reactions.

Iterative Design and Modification Process

After initial testing, students analyze their data to determine how well their device performs. They identify factors that affect thermal energy change, such as substance type, concentration, or insulation quality. Based on this analysis, students modify their device to improve performance, such as changing the amount of chemical, improving insulation, or altering mixing methods. This iterative cycle of testing, analyzing, and modifying is key to engineering design and helps students optimize their solutions.

Scientific Explanation and Communication

Students should be able to explain how their device works in terms of chemical reactions and thermal energy transfer. They should use data from their tests to support claims about whether their device releases or absorbs heat and how design changes affected performance. Clear communication can be through presentations, reports, or discussions, emphasizing evidence-based reasoning and scientific vocabulary.

Worked Examples

Classroom Activity

In small groups, test different substances by dissolving them in water and measuring temperature changes. Record data and discuss which substances release or absorb heat.

Guided Practice

Independent Practice

1. Foundational: What happens to the temperature of water when a substance that absorbs thermal energy is dissolved in it?
2. Developing: Describe how you would test whether a chemical reaction in your device releases or absorbs thermal energy.
3. Application: If your device’s temperature only changes a little during testing, what are two modifications you could try to increase the thermal energy change?
4. Analysis: After testing two different designs, one shows a faster temperature change but less total temperature difference, and the other shows a slower temperature change but a larger total temperature difference. How would you decide which design is better?
5. Challenge: Explain how controlling variables such as the amount of substance, concentration, and time of reaction helps improve the design of a device that releases or absorbs thermal energy.

Independent Practice Teacher Answer Key

1. 1. The temperature of the water decreases because the substance absorbs heat from the water, making it cooler.
2. 2. I would measure the temperature of the substances before mixing and then measure the temperature during and after the reaction to see if the temperature goes up (releases heat) or down (absorbs heat).
3. 3. I could increase the amount or concentration of the chemical substances used, or improve the insulation of the device to reduce heat loss to the environment.
4. 4. I would consider the purpose of the device—if quick temperature change is more important, I might choose the first; if a larger total temperature change is more important, I might choose the second. I could also combine features of both designs to optimize performance.
5. 5. Controlling these variables allows us to understand how each factor affects thermal energy change. By adjusting them systematically, we can find the best combination that maximizes heat release or absorption, making the device more efficient and predictable.

Guiding Questions

• What chemical reactions can release or absorb thermal energy?
• How can we measure thermal energy changes during a reaction?
• What variables affect the amount of thermal energy released or absorbed?
• How can we improve our device to maximize thermal energy change?
• What evidence supports our explanation of how the device works?

Common Misconceptions

• All chemical reactions release heat; none absorb heat.
• Temperature changes during a reaction are always large and easy to observe.
• Adding more substance always increases temperature change proportionally without limits.
• Thermal energy changes happen instantly and do not depend on reaction time.
• Once a device is built, it cannot be improved or modified.

Differentiation

Assessment

• Observe students during testing and note their ability to measure and record temperature changes accurately.
• Ask students to explain the difference between exothermic and endothermic reactions in their own words.
• Review students’ design plans and modifications for evidence of iterative thinking.
• Describe one way your device releases or absorbs thermal energy.
• What did you change in your device to improve its performance and why?
• Write a report explaining how your device works, including data from your tests and how you modified the design.
• Create a presentation that shows your design process, test results, and scientific explanation of thermal energy changes.

Answer Guide

• What type of reaction occurs when the temperature of a solution decreases during a chemical process?
  Answer: An endothermic reaction occurs because the solution absorbs thermal energy, causing the temperature to drop.
• How can you tell if a chemical reaction is exothermic from temperature measurements?
  Answer: If the temperature increases during the reaction, it indicates an exothermic reaction releasing heat.
• Why is it important to modify your device after testing?
  Answer: Modifying the device helps improve its performance by addressing issues found during testing and optimizing thermal energy changes.
• What variables should you control when testing your device?
  Answer: Variables such as amount of substance, concentration, and time of reaction should be controlled to ensure accurate and comparable results.
• How does the iterative design process help in engineering a device that releases or absorbs thermal energy?
  Answer: It allows repeated testing and modification based on data, leading to improved and optimized device performance.

Real-Life Application

Encourage students to observe and discuss examples of thermal energy changes at home, such as ice melting, cooking, or using cold packs, and explain the chemical processes involved.

Homework or Home Connection

• Encourage students to observe and discuss examples of thermal energy changes at home, such as ice melting, cooking, or using cold packs, and explain the chemical processes involved.

Lesson Summary

This lesson guides Grade 6 students through designing, testing, and improving devices that release or absorb thermal energy via chemical reactions. Students learn to measure temperature changes, control experimental variables, and apply iterative engineering design principles. Through hands-on investigation and data analysis, they develop a deeper understanding of exothermic and endothermic reactions and how chemical processes can be harnessed to transfer thermal energy effectively.

Teacher Notes

Use the exact standards alignment and retrieved-source provenance stored with this enrichment.

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