Using AACT Resources to Teach Thermochemistry and Thermodynamics

By Kim Duncan on April 5, 2018

As chemistry teachers plan activities for their students, AACT will highlight resources from our high school library that help to reinforce topics in different units throughout the school year.

In our last news post, we looked at classroom resources that focused on teaching aqueous solutions. Now we are moving on to lessons and activities that can be used to support a unit plan for teaching thermodynamics. This includes endothermic and exothermic processes, enthalpy, Hess’s Law, entropy, and free energy.

Many teachers start their thermodynamic unit with a study of heat transfer, specific heat capacity, and calorimetry. These topics were covered in our February 22, 2018 news post about Phase Changes and Heat Transfer.

Identifying the direction of energy flow during a physical or chemical process is a difficult concept for many students to master. The activity What Makes Something Feel Warm engages thinking about energy in chemistry and the nature of thermal transfer. This activity will allow students to construct a macroscopic model that represents how energy is transferred and explain how their perception of hot and cold is related to heat and temperature. Alignment to NGSS is included in this resource.

Use the Energy Changes in Chemical Reactions simulation from the November 2016 issue of Chemistry Solutions to introduce the topic of exothermic and endothermic reactions. This simulation allows students to evaluate the energy changes in different reactions and compare how energy is absorbed and released during the reaction process. Students will also learn how to connect energy diagrams with each reaction type.

After introducing the topic of enthalpy of a reaction, have students complete the lab, Determining Endothermic and Exothermic Reaction. During this hands-on activity, students carry out two common reactions and analyze evidence to determine if energy is released or absorbed. After making observations and drawing conclusions about the direction of energy flow, students are then tasked with determining if other common physical and chemical equations are exothermic or endothermic. You might also consider using the Endothermic & Exothermic Reactions activity to help students understand the difference between the two processes.

Use -our Hess’s Law lesson plan to teach your students about the concepts of Hess’s Law and problem solving techniques involving them. This lesson includes a PowerPoint presentation along with a student activity sheet and answer key.

In a related lesson plan, Hess’s Law Application, students determine the value of DH of an unknown reaction through laboratory data collection using calorimetry and Hess’s Law. This lesson also includes a formative quiz to access student’s readiness for the lab activity as well as answer keys for the quiz and example lab data. Additionally, it includes ties to the AP Chemistry Curriculum Framework.

The Entropy activity will help students define the concept and be able to recognize entropy changes in chemical reactions. The lesson includes a PowerPoint presentation, which introduces the topic with pictures of everyday items, then moves on to discuss changes in physical state, and ends by investigating changes that result from a chemical reaction. Consider following this introduction with the activity, Connecting States to Entropy, which uses blocks to model different states of matter.

The Enthalpy and Entropy as Driving Forces lesson plan will help students see the connections between enthalpy, entropy, and free energy. Students engage in an activity to observe various chemical and physical processes to qualitatively predict and explain the signs of ∆S and ∆H. Based on their observations, they then predict the sign of ∆G and determine the driving force of the process. This lesson focuses on thermochemical predictions, calculations and explanations and includes alignment with the AP Chemistry Curriculum Framework.

We hope that these activities can help you to reinforce several of the topics covered in a unit about thermodynamics. Most of these lessons were made possible by great teachers who shared their own resources. We need your help to keep the collection growing. Do you have a great demonstration, activity, or lesson related to this topic that you would like to share with the community? Please send it along for consideration.