Nuts about Energy!
Becki M. Campanaro
Key Words: Energy, calorimetry, food chemistry, nutrition, thermodynamics
Overview: This lesson developed from a close partnership between my partner teacher and myself. It was her request that I develop a lesson to be included in a unit on Energy. We worked together pulling our experiences and resources resulting in the final product seen here. This lesson was used in a core high school chemistry class consisting of students from grades 10 through 12, but it could easily be adapted to be used in lower grades.
Time: This lesson took place over a 3-week period as follows. On Tuesdays and Thursdays, we meet with three sections of students (1, 3, and 5) for 100 minutes. On Wednesdays and Fridays we meet with our other two sections of students (4 and 6) for 100 minutes. On Mondays we meet all sections for 45 minutes.
Monday / Tuesday / Wednesday / Thursday / FridayLesson 1
Lesson 2 / Lesson 3 / Lesson 3 / Lesson 4 / Lesson 4
Lesson 4 / Lesson 5 / Lesson 5 / Lesson 5 / Lesson 5
Lesson 6 / Lesson 7 / Lesson 7 / Exam / Exam
Standards Addressed:
1.1.2 – Develop questions from observations that transition into testable hypotheses.
1.1.3 – Formulate a testable hypothesis.
1.2.2 – Identify the resources needed to conduct an investigation.
1.2.3 – Design an appropriate protocol (written plan of action) for testing a hypothesis.
1.3.7 – Propose further investigations based on the findings of a conducted investigation.
1.4.2 – Produce graphs that communicate data
1.4.3 – Communicate results clearly and logically
1.4.4 – Support conclusions with logical scientific arguments
5.3.1 – Describe the following ways in which energy is stored in a system: mechanical,
electrical, chemical, nuclear.
5.3.3 – Recognize that energy is conserved in a closed system.
5.3.4 – Calculate quantitative relationships associated with the conservation of energy.
5.3.6 – Distinguish between heat and temperature.
5.5.1 – Describe various ways in which matter and energy interact.
Materials:
Peanuts
Cashews
Brazil nuts
Pecans
Almonds
Hazelnuts
Bunsen burner
Matches/striker
Candles
Water
Test tubes (various sizes)
Beakers
Corks
Aluminum foil
Thermometers
Aluminum cans
Ring stands
Rings and wire gauze
Test tube holders
Thermometer clamps (optional)
Graduated cylinders
Balances
Pencil and paper
All handouts
Schedule:
Lesson 1 (45 minutes): Students are assigned the “You’re in Hot H2O” experiment to perform at home prior to coming to class. In class, students will list on the board the amount of time it took him/her to boil H2O. A class discussion will follow to help students understand what constitutes a valid experiment. This discussion can be done at any point leading up to the Energy unit, and need not be done immediately before Day 2 events.
Lesson 2 (45 minutes): Students will be introduced to the concept of heat through two simple laboratory experiences using one endothermic and one exothermic reaction taking place in small plastic baggies. This will lead to a group discussion of heat, temperature, and eventually energy. Because the definition of energy as “the ability to do work” is so vague for students, we feel that by connecting to energy via this route, the students will have a better understanding of how energy is understood in chemistry.
Lesson 3 (100 minutes): This class period will start off with an in class recreation of Dr. Art’s Matter and Energy demonstration. This will then be used to continue the energy discussion specifically looking at the conservation and conversion of energy. This discussion will lead into a discussion of calorimetry where students will figure out the elements necessary to quantify energy. Following the discussion, students will do a short experiment to give them experience with energy calculations. At the end of this class period, students should have the necessary background information to perform the remainder of the laboratory exercise.
Lesson 4 (100 minutes): Students will be given a written document that outlines a Wolf Candy Company’s request of their “chemical company” to test various nuts for the amount of energy found in each. Students will additionally be given the scaffolding sheet to help them scaffold their thinking as they plan experiments for completing their assigned task.
Lesson 5 (100 minutes): Students will experiment.
Lesson 6 (100 minutes): Students will be given time to finish experimenting (if necessary) and to compile their data, make graphs, and begin putting together the final product.
Evaluation: Students will be graded in several areas including calculations sheet, protocol development, laboratory technique, and final report. Rubrics will be created that will allow for ease of grading of all student work.
Lesson 1 – You’re in Hot H2O
Time:
45 Minutes
Objectives:
· Students will be able to discuss factors that affect the time it takes to boil water.
· Students will be able to describe factors necessary for conducting a valid experiment.
Previous Knowledge:
· No prior knowledge is assumed.
Materials:
You’re in Hot H2O Worksheets (1 per student)
Pencil and Paper
Lesson:
· Students must have been given the “You’re in Hot H2O” assignment prior to coming to class on this day.
· Go around the room and ask students why kinds of questions they had as they were going through the experiment at home. This will most likely produce questions like, “Does the amount of water I use matter?” and “How do I know when the water is boiling?” These questions can be addressed in the discussion that will follow.
· Have students list their time to boil H2O on the board. Circle the greatest amount of time and the least amount of time. Have students calculate the difference between the two times.
· Ask students why there may be such a great range of times obtained by the class. Relate this back to some of the questions that they had at the beginning of class.
· Discuss the validity of the experiment that the students performed and what constitutes a truly valid experiment.
Evaluation:
· Students will turn in their “You’re in Hot H2O” worksheet for grading. Points will be awarded on whether the assignment was turned in or not.
Lesson 2 – Introduction to Energy (Endo/Exo)
Time: 45 Minutes
Objectives:
· Students will be able to explain the first law of thermodynamics.
· Students will be able to define and identify differences between heat, temperature, and energy.
· Students will be able to understand the difference between endothermic and exothermic reactions and the energy changes associated with each.
Previous Knowledge:
· No prior knowledge is assumed.
Materials:
CaCl2
NH4NO3
Water
Graduated cylinders
Balances
Endo/Exo worksheets (1 per student)
Paper and pencils
Small plastic baggies
Lesson:
· Put students in groups and give them the Endo/Exo worksheets. Ask them to write detailed responses to the questions.
· Come back together as a class and discuss what the students found in their groups.
· Open a discussion on heat that leads into a discussion on temperature and then into energy. Use the worksheet questions as a starting point to get the students to think about heat and the flow of heat. Once a definition has been established for heat (energy transferred between two objects due to a temperature difference between them), ask students what temperature is. Let them know that temperature is a measure of the average amount of kinetic energy. From here, a discussion can open on what is energy, and the various types of energy. This will be the starting point for the introduction to the 1st law of thermodynamics in the next lesson.
Evaluation:
· Students will turn in their “Endo/Exo” worksheet for grading. Points will be awarded on the completeness of the responses.
Lesson 3
Time: 100 Minutes
Objectives:
· Students will be able to identify various forms of energy.
· Students will be able to discuss ways in which energy is converted from one form to another and recognize that energy is conserved in a closed system.
· Students will be able to describe various ways in which matter and energy interact.
· Students will be able to identify the factors that are necessary for calculating heat energy.
· Students will be able to calculate quantitative relationships associated with the conservation of energy.
· Students will be able to conduct a simple calorimetric experiment.
Previous Knowledge:
· Heat as a form of energy
· Familiar with the 1st law of thermodynamics
Materials:
Sun, plant, and cow costumes
Dr. Art “Energy Flows” scripts
Pencil and Paper
Ring stand with ring
Wire Gauze
Beakers of water
Thermometer
Bunsen burner and striker
How much Energy to Boil H2O worksheets
Lesson:
· Have students run through the Dr. Art Sun, plant, and cow skit. Mention how this skit demonstrates the law of conservation of mass that we learned earlier in the semester. Make sure that students realize that the energy is released as heat, but that the energy of the universe is conserved. Ask students the following questions:
· What kinds of energy were illustrated in this skit?
· What are some examples of energy conversions in this skit?
· What are some examples of energy conversions that we encounter in everyday life?
· Move to asking students the question, “How can we quantify energy?”
· Scaffold their thinking about this by having a basic calorimetric set-up at the front of the class. Have one beaker with about 50mL of water and one with 100mL of water. Ask the students if they think that it would take the same amount of energy to boil both beakers of water. Based on their responses, draw out of them that obviously volume/mass is important for calculating energy.
· Ask the students if they think it would require the same amount of energy to boil water that came out of the refrigerator and water that was sitting in the Arizona sun. Based on their responses, draw out of them that it is not the initial or final temperature that is important, but the change in temperature that is important when calculating energy. Explain to them the meaning of the ∆ symbol as a change in something (Tf – Ti).
· Ask the students if they’ve ever wondered why we don’t have metal playground equipment Phoenix, or if they have every noticed how sand on the beach feels hot, but the water at the beach isn’t that hot. Ask if they know how it is possible for someone to walk barefoot over hot coals. Draw out of them that they already understand something about heat capacity from these observations.
· Give them the definition of heat capacity as the heat required to raise the temperature of 1 gram of a substance by 1°C. Based on this definition, what do you think that the units are on heat capacity?
· Explain to them that the heat capacity of water is very high meaning that it requires a lot of energy to increase the temperature of water by 1°C.
· Give them the heat capacity of water at 4.18 J/g*°C.
· Now that we have all of the pieces for calculating heat energy, give them the equation as q = m*C*∆T and have them figure out what the units will be on q.
· Have students go to the lab in their groups and determine the heat (energy) necessary to boil 200 mL of water after which they will answer questions on the calculations sheet.
Evaluation:
· Students will turn in their “Endo/Exo” worksheet for grading. Points will be awarded on the completeness of the responses.
Lesson 4 – Wolf Candy Company
Time: 100 Minutes
Objectives:
· Students will be able to formulate a testable hypothesis about the energy in the various nuts.
· Students will be able to identify the resources needed to conduct an investigation.
· Students will be able to design an appropriate protocol for testing their hypothesis.
· Students will be able to understand the difference between endothermic and exothermic reactions and the energy changes associated with each.
Previous Knowledge:
· Understanding of ways in which energy can be stored in a system.
· Understanding of the ways energy can be converted and the 1st law of thermodynamics.
· Understanding of the factors that are necessary for calculating heat energy and an ability to calculate quantitative relationships associated with the conservation of energy.
· Familiarity with one type of calorimetric set-up.
Materials:
Peanuts
Cashews
Brazil nuts
Pecans
Almonds
Hazelnuts
Bunsen burner
Matches/striker
Candles
Water
Test tubes
Beakers
Corks
Aluminum foil
Thermometers
Aluminum cans
Ring stands
Rings
Wire gauze
Test tube holders
Thermometer clamps
Graduated cylinders
Balances
Pencil and paper
Wolf Candy Company Handouts
Lesson:
· Students will be given a written document that outlines a Wolf Candy Company’s request of their “chemical company” to test various nuts for the amount of energy found in each. Let students work in groups and walk around to the groups to facilitate their conversations and keep them on task. When it seems as though most groups are stalled, write a question on the board from the list of the following and ask students to take a look:
· Have you considered what pieces of data you’ll need to collect?
· Have you considered what kind of energy is in the nut? What other things do you know of that have that same kind of energy?
· Have you considered how the energy is released from fossil fuels? How might this help you determine how to get the energy out of the nut?
· Have you considered measuring the energy in the nut directly? What pieces of data would you need to collect in order to do this? Is it possible?
· Have you considered using the energy from the nut to do some work? Can you determine the energy in the nut this way?
These questions should scaffold the thinking of the students, but give them enough time to arrive at answers for themselves. Some groups may get there faster than others and not need too much scaffolding from the instructor. Be open to the use of many different experimental set-ups as these can lead to interesting learning outcomes by the students.
Evaluation:
· Students will be evaluated based on their participation within the group and their ability to stay on task. These will be factored into their class participation points.