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What Happens to the Heat?

Grades: Middle School - Grade 7
Author: Charles Miller
Source: This material is based upon work supported by the National Science Foundation under Grant No. EEC-1161732. Aerogel Technologies, LLC - Aerogel Superinsulation Blowtorch Demo: Hershey's Kiss https://www.youtube.com/watch?v=5sw1tNeJ0Rw. American Chemical Society - Middle School Chemistry http://www.middleschoolchemistry.com/lessonplans/chapter2/lesson1. (This lesson provides a procedure to examine heat transfer using metal washers and water). Nuffield Foundation – Thermal Chemistry of Water http://www.nuffieldfoundation.org/practical-chemistry/thermal-properties-water. The Concord Consortium – Molecular Workbench http://mw.concord.org/

Abstract

Students will initially visualize the concepts of conduction and insulation through a discrepant event demonstration where materials are heated at high temperatures to show that certain materials will heat up more quickly than others. Afterwards, students will investigate these same concepts using round washers made of different materials to quantify energy transfer through temperature changes. Students will then participate in an interactive activity to define random motion, absolute zero, heat conduction, heat conductor, thermal equilibrium, closed systems, thermal radiation, and photons as well as develop a strong understanding of thermal energy transfer through conduction and radiation. Finally, students will design and create a device to reduce or increase thermal conduction and measure temperature change between real objects as a culminating activity.

Objectives

What should students know as a result of this lesson?

Differentiate between heat and temperature.
Define terms associated with the transfer of thermal energy.
Explain how thermal energy is transferred between materials through the process of conduction.
Describe the movement of energy between atoms through the process of radiation.
Differentiate between conduction and radiation.

What should the students be able to do as a result of this lesson?

Define "heat" as the transfer of energy from one object to another due to differences in temperature (average kinetic energy).
Distinguish heat from temperature (as a proportional measure of the average internal kinetic energy per atom or molecule in a system).
Measure heat transfer in terms of temperature change.
Infer that heat transfers from areas of higher temperature (energy) to areas of lower temperature (energy).
Describe thermal conductivity in terms of atomic collisions.
Compare the conductivity of different materials.
Design a physical model or poster depicting the conduction of thermal energy between three objects in everyday life.
Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed.

Materials

1 x Bunsen burner/Meeker burner/Butane torch
3 x ring stands
3 x iron rings
4 x 4 x 1/4 in³ balsa wood plate
4 x 4 x 0.19 in³ aluminum plate
Pyrogel XT Blanket ($30 at http://www.buyaerogel.com/product/pyrogel-xt/)
3 x Hershey’s kiss candies
1 x hot plate/large coffee maker
1 x 1000 mL beaker/large coffee pot
1” washers – 36/ material
- Aluminum – material 1
- Mica – material 2
- Polyurethane – material 3: A metal, ceramic and polymer are suggested. These can all be purchased from an online vendor like McMaster Carr (http://www.mcmaster.com). Any other washer materials can be substituted here. It is useful to use at least on good heat conductor (like a metal) and a poor heat conductor (a polymer)
10” string for each grouping of washers
32 standard styrofoam cups
7 x 50 ml Graduated cylinders
6 x 50 ml of hot water (70 degrees C)
6 x 50 ml of room temperature water (22 degrees C)
7 x thermometers
7 x stopwatch
calculators
Computers for each student or group, and Internet access

Procedures

Engagement

Students should sit at their desks or at a safe distance from the demonstration table (in a well-ventilated area) or fume hood during this teacher demonstration. Reducing the light in the room may increase interest as some materials will emit light as they burn. This demonstration is best performed in a fume hood or in a large room, when available. If you do not have the facilities for this demonstration, as a discrepant event alternative, you may wish to show the following video produced by Aerogel Technologies, LLC - Aerogel Superinsulation Blowtorch Demo: Hershey's Kiss.

A second discrepant event that may be used to introduce the concept of conduction has been produced by the Nuffield Foundation called the Thermal Properties of Water and may be an alternative to the previous demonstration.

Teacher Preparation

Set up three ring-stands with iron rings holding the Aerogel plate, aluminum plate, and balsa wood plate.
Place one Hershey Kiss® on the top of each material in the center of the plate.

Demonstration

Before beginning the demonstration describe what you will be doing at the beginning. Do not tell the students the makeup of each substance on the ring stand; merely tell them that you have three different materials that you will be heating with a burner. (You may label them as material 1, 2, and 3 or something like this.) Hold up a wrapped Hershey Kiss® and ask the students what happens when they hold an unwrapped Hershey Kiss® in their hand on a hot day. Students should recognize that the chocolate will melt in their hands.
Ask students to predict an outcome before heating each material.
Using a Bunsen burner, Meeker burner, butane torch, or heat gun (no higher than 250℃), heat the underside of each plate starting with the balsa wood, then the aluminum, then the Aerogel.
Students should write down their observations after heating each material.
Once each material and Hershey Kiss® have cooled, place the heated materials into a clear plastic container with a lid (a zip lock bag may be substituted) and pass the materials around for the students to observe the results of the demonstration up close. (If a document camera is available, the teacher may present the products of each reaction on visually.) If students are allowed to handle the materials, remind them that the materials may be brittle, and therefore, should be handled with care.
Students should write down observations for each material in the container and draw a picture, if possible, of the left over materials.

Expected Outcome

Students should notice that the wooden plate and Hershey Kiss® are completely burned, the metal plate is mostly undamaged, however, the Hershey Kiss® is completely melted, and the Aerogel and the Hershey Kiss® are both basically undamaged.

Assessment: Students should complete the demonstration handout with their initial predictions, observations, and final drawings.

Exploration

Teacher Preparation

Use a 10” string to tie 3 washers together for each type of material. Each group of students will need two sets of each material, one as a control and one as a test material. (Note – some washers will also need a weight to hold them under water due to low density. A common 1/4 – 3/8 oz. split shot fishing weight should hold a washer under water.
Hang one set of washers for each group, in advance, in hot water on a hot plate or in a coffee maker/hot pot so that the washers can get hot. These washers will need to remain hot until the second half of the activity. Make sure to put lids on the Styrofoam cups to keep the temperature of the water/materials as high as possible.
The other set should be left at room-temperature and may be distributed to students along with the materials for the activity.
Before starting the activity, pour about 100 milliliters (3.5 tablespoons) of hot water (70 °C) into a Styrofoam cup for each group. Be sure to pour one cup of hot water for you to use as a control.

At the beginning of the laboratory tell students that they are going to measure the change in temperature of hot water as a result of placing room-temperature washers of various types into it. They will do this at least three different times. The only way to tell if the washers cause the temperature to change is to have a cup of hot water without washers. Explain that you will have this cup of hot water, which will be the control.

You will need to place your thermometer in the cup of hot water at the same time the as the students. Have students record the initial temperature of the control in their charts on the activity sheet, along with the initial temperature of their own cup of hot water. The temperature of the two samples should be about the same.

Expected Results

The temperature of the water will decrease for the metals, and the mica. The temperature of the polyurethane should stay mostly. The temperature of the washers will increase a bit for the metal and ceramics and remain mostly unchanged for polyurethane. The amount of temperature decrease is important for students to differentiate between conductivity of substances.

Assessment: Students should complete the laboratory handout as an assessment.

Explanation

Students will develop vocabulary and concept understanding of conduction and radiation of thermal energy between materials using a http://workbench.concord.org/database/activities/308.html#benchmarks.

The Molecular Workbench, produced by the Concord Consortium, is an award winning interactive website that allows students to study concepts in physics and chemistry. Each series of activities has embedded assessments that can be printed out at the end of the activity by each student.

You must have Java to run the applets for these activities. Applets run on Mac, Windows, and Linux computer platforms.

Assessment: Students should complete questions during the activity and print out the final document as the assessment.

Elaboration

Students will participate in a project-based activity where they will be required to create a model or poster that explains the conduction of heat between two or more objects. Each model or poster must identify the materials, the transfer of heat through conduction, and explain the movement of energy through the model. Each project will be graded using a rubric.

Prerequisites

Students should know the following:

Definitions of energy, atoms, and molecules, states of matter
Describe the difference between solids, liquids, and gases in terms of distance and energy between atoms/molecules.

Best Teaching Practices

Teaching for conceptual change
Scientific literacy
Metacognition
Simulations/Role Play
Hands-on/Minds-on learning
Inquiry approaches
Using Analogies
Authentic Problem Based Learning
Discrepant Events
Learning Cycle

Alignment with Standards

NGSS Standards:

MS-PS1-4. Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed.
MS-PS3-3. Apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal energy transfer.
MS-PS3-5. Construct, use, and present arguments to support the claim that when the kinetic energy of an object changes, energy is transferred to or from the object.

Common Core Standards:

RST.6-8.3 Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks. (MS-PS1-6)
RST.6-8.7 Integrate quantitative or technical information expressed in words in a text with a version of that information expressed visually (e.g., in a flowchart, diagram, model, graph, or table). (MS-PS1-1),(MS-PS1-2),(MS-PS1-4),(MS-PS1-5)
WHST.6-8.7 Conduct short research projects to answer a question (including a self-generated question), drawing on several sources and generating additional related, focused questions that allow for multiple avenues of exploration. (MS-PS1-6)

Ohio Standards:

Science New Model Curriculum:
Energy can be transformed or transferred but is never lost.
Energy can be transferred through a variety of ways.
Identify questions that can be answered through scientific investigations;
Design and conduct a scientific investigation;
Use appropriate mathematics, tools and techniques to gather data and information;
Analyze and interpret data;
Develop descriptions, models, explanations and predictions;
Think critically and logically to connect evidence and explanations;
Recognize and analyze alternative explanations and predictions; and
Communicate scientific procedures and explanations.

Content Knowledge

Thermal Conduction is the transfer of heat energy by contact or collision.
Thermal Radiation is the transfer of electromagnetic radiation produced by all substances above absolute zero.
Elements are examples of different types of atoms.
Molecules are composed of atoms and held together by chemical bonds.
See procedure for technology links.

Safety

Goggles for the teacher
Goggles for the students
Bunsen burners or other heating devices should always be treated with caution. Heating or burning materials should be done in a well-ventilated area or fume hood.
Hot plates are hot. Do not touch the surface. Demonstrate the use of the back-of-hand temperature test method.
Remind students that heating a substance on a hot plate may produce a volatile material that can burn them.

Applications

Common knowledge used in everyday life to heat anything using contact with other warmer objects.

Assessment

This lesson was designed to incorporate the Learning Cycle. Student Assessment is embedded in the four major components of the lesson.

Other Considerations

Grouping Suggestions: Students should be placed in groups of four. The teacher may wish to give group members specific “jobs” to enhance group interaction.

Pacing/Suggested Time: Engagement: 20 minutes; Exploration: 60 – 90 minutes depending on the number of materials studied; Explanation: 45 – 60 minutes; Elaboration: 90 – 120 minutes (Homework assignment may be given if more time is needed.); Total time: 125-260 minutes.

Printable PDF Worksheets

What Happens to the Heat? Demonstration Sheet

What Happens to the Heat? Laboratory Sheet