Using AACT Resources to Teach Reaction Energy

Concepts related to energy changes can be found throughout the year in a chemistry course. In the AP Chemistry Curriculum Framework the concept is outlined in Big Idea 5: The laws of thermodynamics describe the essential role of energy and explain and predict the direction of changes in matter.

Most students believe that they have a good understanding of energy; in reality, many have misconceptions about the subject. I found that it’s difficult for students to comprehend is the difference between endothermic and exothermic changes, and more specifically, differentiating between how those changes differ between chemical and physical changes. The following AACT resources can help your students develop a better understanding of this topic.

• The Endothermic & Exothermic Reactions activity can be used as a lab or class demonstration to allow students to observe industrial-strength snap sticks and chemical cold packs, then discuss processes of endothermic and exothermic reactions.
• In the Designing Exothermic and Endothermic Reactions lab, students construct a reproducible procedure that can be supported with data for a reaction that either releases or absorbs thermal energy.
• Many students assume that all exothermic reactions happen are combustion reactions that happen quite fast. The Potassium Permanganate Demo shows students that a chemical change, even one that is exothermic, does not have to happen quickly.
• Students can interact with the Reversible Reactions Simulation, to investigate how temperature, activation energy, initial amounts of products and reactants, and type of reaction (exothermic or endothermic) effect the equilibrium position of a reaction.
• From the March 2015 issue of Chemistry Solutions, “Energy Foundations for High School Chemistry” highlights a website dedicated to energy related teaching resources.

Some students struggle with calculations concerning heat transfer using lab data and heat capacity. Often there is an issue with the correct sign for the heat that is being exchanged. The following AACT classroom resources can be used to help your students master these calculations.

• The Understanding Specific Heat lab introduces the idea of specific heat by mixing various liquids at different temperatures.
• Students can consider stoichiometry, concentration, and calorimetry when they use the Less Than Zero lab to investigate an endothermic reaction.
• Students collect data and calculate the heat of neutralization from an exothermic reaction in the Heat of Neutralization lab.

Do you have a great AP demonstration, activity, or lesson about any topics related to teaching concepts related to Thermodynamics that you would like to share with the community? We are proud to feature teacher-submitted activities in the classroom resource collection. If you want to share something you use in your classroom with the community, please send it along for consideration.