Scientists can't observe bonds breaking or forming, so how do they distinguish between exothermic and endothermic reactions? Young scholars complete two experiments to do just that. They monitor temperature change and calculate the enthalpy of the reactions.

Concepts

exothermic reactions, endothermic reactions, chemical changes, chemical reactions, heat of reaction, enthalpy, enthalpy change, thermochemistry

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Additional Tags

science

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Instructional Ideas

• Before the experiment, review the Law of Conservation of Energy, how to balance chemical equations, and the mechanics of chemical changes

Classroom Considerations

• Follow standard safety guidelines as some vapors can be irritating and other chemicals irritate body tissue
• Relies heavily on prior knowledge of chemical versus physical change

Pros

• Uses standard laboratory equipment and materials
• Offers an extension to meet the AP requirements

Cons

• None

Common Core

RST.9-10.3 RST.9-10.4 RST.11-12.3 RST.11-12.4