The Energy Debate – Energy of Peanut

Written for PULSE by Christopher Martin

Edited By: Stephanie Nardei

Time: / 1 class period
Preparation Time: / 20 minutes
Materials: / Lab - Energy of a peanut
Boiling tube
Thermometer
Peanuts
Balance
Cork with pin
Measuring cylinder
Bunsen Burner
Selection of fuels

Abstract

Students will learn that a tiny peanut contains stored chemical energy. When we eat them, the stored energy is converted by our bodies so we can do work. We can also use the energy in a peanut to heat a container of water.

Objectives

Students will be able to:

  1. Articulate the difference between the terms heat and temperature
  2. Calculate the amount of energy associated with a given temperature rise
  3. Design an experiment to measure the energy of a fuel

National Science Education Standards:
CONTENT STANDARD E: The Physical Setting

Energy Transformations

Different energy levels are associated with different configurations of atoms and molecules. Some changes of configuration require an input of energy whereas others release energy.

Strand 5: Physical Science

Concept 4: Chemical Reactions Investigate relationships between reactants and products in chemical reactions. PO.10 Explain the energy transfers within chemical reactions using the law of conservation of energy.

Concept 3: Conservation of energy and increase in disorder. PO.6 Distinguish between heat and temperature.

Teacher Background

Related and Resource Websites

Science Help Online Chemistry

Science Projects Peanut Power taken from here)

Energy of a Peanut: An Experiment in Calorimetry By David Katz

The Energy Inside a Peanut

Activity

  1. Start class by asking students to define what energy is. Students may suggest different forms of energy. Dependent upon the background of your students you may wish to ask them to explain how each form of energy differs. How do you measure different amounts of heat energy? What scales are used for measuring differences in heat?
  2. Explain to the class that the energy of a fuel can be measured by using the fuel to heat water. The specific heat capacity of water is 4.2 J/g/C. This means that it takes 4.2 Joules of energy to cause the temperature of 1 gram of water to rise by 1 degree Celsius.
  3. In this lab the students will use a peanut as a fuel to heat the water. What other fuels could be used?
  4. The teacher will demonstrate the lab reminding students to be work safely with the Bunsen burner and to ensure that the cork doesn’t ignite with the peanut.
  5. Students should follow the instructions on the worksheet to measure the energy of a peanut. In conclusion, students should write “The fission of 1 gram of uranium 235 releases 78.5 Giga Joules of energy. The energy of one gram of peanut is ……… joules.”
  6. Finally, students will design a new lab to find the energy of another fuel. This will be completed in the second class period. Students should be advised to increase the volume of water with fuels of higher energy content.

Embedded Assessment

Students shall be assessed on their lab report for the energy of a peanut. Understanding of the formula to calculate energy should be a vital part of the grade. Ability to follow directions and work safely will be provide observed assessment. Finally, the design of a second lab will assess the students’ understanding of energy measurements as they transfer skills to test a new fuel.