Using AACT Resources to Teach Phase Changes and Heat Transfer

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 resources that focused on the gas laws. Now we are moving on to lessons and activities that can be used to support a unit plan for teaching phase changes and heat transfer. This includes exploring kinetic molecular theory, phase changes, heat capacity calculations, and calorimetry.

Start this unit by exploring the difference between bond and molecular movements with The Molecular Dance. This activity shows students how to mimic molecular motion and distinguish between bonds and interparticle forces. Movements explored include the stretching, bending and rotating properties of a bond, as well as the vibration, rotation, and translation movements of molecules. After completing this introductory activity, use the Density simulation to help students analyze movement and energy of different states of matter at the particle level as temperature is increased or decreased.

Another quick activity that allows students to observe the effect of temperature on molecular motion is the demonstration, What is Temperature. This classroom demo helps students explain how temperature is related to average kinetic energy and challenges them to explain what a temperature measurement really means, using supporting evidence.

Move on to the activity, Visualizing States of Matter, which has students view, sort and classify pure substances and mixtures into the 3 common states of matter found in the laboratory. It also includes alignment with the NGSS. By the end of this activity, students will able to classify the three states of matter using molecular level particle representations, identify differences in the particle representations to classify them as pure substances, both elements and compounds, and verbally explain the classification system they developed.

Use the Heating Curve of Water simulation to introduce the concepts of heat capacity and phase changes. In this simulation, students investigate qualitatively and quantitatively what happens as water changes temperature and states. This lesson accompanies the simulation from the May 2015 issue of Chemistry Solutions. By the end of this lesson, students will understand the difference between the states of matter, discover that when a state change occurs, a temperature change does not take place, and quantify how much energy it takes to heat water from one temperature to another.

Next, move on to the Heating & Cooling Curve lab, where students create a phase change graph by adding and removing heat to observe and record data during actual phase changes. Instead of just memorizing a heating/cooling curve they see in a textbook, students will create their own. They will also determine the freezing and melting point temperatures of a pure substance.

After exploring temperature and phase changes for water, use another lab, Understanding Specific Heat to help students investigate what happens when two liquids at different temperatures are mixed. This lab will help students understand that all liquids do not have the same heat capacity and behave differently with respect to heat transfer.

Then, use the Dramatic Demonstration of Thermal Conductivity to introduce heat capacity of metals. . This entertaining classroom demo will show students how low the heat capacity of copper metal is. Follow it up with the Measuring Heat demonstration, which allows students to collect data when two liquids at different temperatures are mixed and also when a liquid and a solid at different temperatures are mixed. By the end of this demonstration, students will understand that each substance has its own unique heat capacity and that the amount of heat transferred when two substances are mixed depends upon several variables, including: initial temperature, mass, and specific heat capacity.

Finish up your study of heat transfer with the lab, How Much Energy is in Your Snack Food, which allows students to calculate the amount of heat energy stored in some of the foods they eat. This lab will help students understand the law of conservation of energy in addition to letting them measure the heat released by common snack food.

We hope that these activities can help you to reinforce several of the topics covered in a unit about phase changes and heat transfer. 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.