CHEMISTRY NOW: Role of Energy in Cooking (Grades 5-8)
Students will be able to describe how heat plays a role in cooking foods.
CHEMISTRY NOW: The Role of Energy in Cooking
Subject Area: Chemistry
Grade Level: Middle School Chemistry
Lesson Title: The Role of Energy in Cooking
National Science Standards:
Science as Inquiry: 5-8, Content Standard B
Physical Science Standards:
Physical Science: 5-8, Content Standard B
Science and Technology: 5-8, Content Standard E
Science in Personal & Social Perspectives: 5-8, Content Standard F
History and Nature of Science: 5-8, Content Standard G
Suggested Prior Knowledge: kinetic energy, conservation of energy,
Purpose: Students will understand the connection between kinetic energy and heat and the use of heat to initiate a chemical reaction such as cooking.
kinetic energy - energy of motion; EK = (1/2) mv2 (E=energy, m = mass, v = velocity)
chemical reaction- the transformation of one substance into another. The molecular composition of a substance is changed due to its interaction with other substances.
energy- the capacity to do work or supply heat
heat- the energy transferred from one object to another as the result of a temperature difference between them
Maillard reaction- also known as the "browning reaction" is a chemical reaction between the amino acids in protein and sugars that creates the flavor and smell of meat; named after French scientist Louis-Camille Maillard (1878-1936)
Students will be able to describe how heat plays a role in cooking foods
Materials: (each group should receive the following)
- student worksheet
- 10ml of clear corn syrup
- 1g amino acid powder (available at health food stores) [amino acids will be used as a sanitary way to represent meat/protein]
- stirring rod
- ring stand
- test tube
- test tube extension clamp
- clamp holder
- digital scale
- goggles, lab safety equipment and clothing
1. Discuss heat energy and the role of heat in chemical reactions; discuss student conceptions about energy, some ways energy can be measured, and what has energy. You can use the following questions;
- What is heat and when do we feel it?
Heat is a form of energy. Heat is the amount of kinetic energy a substance has and can be felt when an object has a greater amount of kinetic energy than your skin.
- Can you give an example of a chemical reaction?
Discuss and trace back with students the origin of these sources.
- Do you think it takes more energy to cook a whole turkey vs. a hamburger? Why?
To help students answer this, relate this to the amount of energy needed to cook these foods.
2. Energy is everywhere in our lives. Facilitate a conversation about the practical applications of energy and how it effects so much of what people do. Some questions to facilitate this conversation are:
How many energy conversions can we account for with the following appliances?
1. burning wood [teacher background: when wood burns, it releases energy in the form of heat and light. When we supply heat to wood the bond between glucose molecules break, and carbon, oxygen, and hydrogen become available to form carbon monoxide and carbon dioxide]
2. microwave oven - it accelerates water molecules and increases kinetic energy
3. electric stoves
4. gas stoves
5. cooking on a skillet vs. in a pot of water
6. heat lamp
Where does the energy to cook our food come from?
How does heat cook food?
Heat often changes the molecular structure of proteins or causes the sugars and proteins to recombine to form new products. The Maillard Reaction is an example of a chemical reaction between sugar and amino acids that gives cooked food distinctive smells and tastes.
3. Facilitate an experiment demonstrating types of energy, the conservation of energy, the ability of energy to perform work, and the Maillard Reaction. In this experiment, students will interact and follow the flow of energy throughout the entire process of cooking.
a. Suspend a test tube above a burner. For students with special mobility needs, a non-stick skillet and hot plate can be used instead.
b. Have students record the smell of both the corn syrup and amino acid powder (the corn syrup is used to represent sugars that are naturally found in meats)
c. In the test tube, add 10ml of tap water
d. Add10 ml of clear corn syrup
e. Add 1 gram of amino acid powder (representing the protein in raw meat)
f. Apply heat to the ingredients and stir ingredients until mixed. Do not leave the stirrer in the test tube or it will get hot enough to burn skin. Use heat-proof gloves when appropriate and be sure to let items cool down before touching them.
g. Have the students record their observations. Special notice should be given to the smell and color of the Maillard Reaction.
4. Conclude the experiment with some questions that help students see the connection to energy:
- How do you know the ingredients cooked?
- Was there a chemical reaction? How do you know?
- Can you identify the different types of energy in the process of doing this experiment?
Student Worksheet for The Role of Energy in Cooking
Experiment Title: ____________________ Date: ________ Name: _________________
Develop a guiding question or questions for your experiment: ________________________________________________________________________
Observation (smells, appearances):
Conclusion (use the back if necessary):