# Heat Transfer through Popping Popcorn

By Laura Hospitál on Apr 05, 2016

Students will observe heat transfer by conduction, convection, and radiation as they pop popcorn.  This activity can be used as an intro to these concepts or after initial instruction on the concepts. The lesson ends with a tasty treat!

### Related vocabulary:

• heat - flow of energy from warmer to cooler substances
• heat transfer - heat moves from one substance to another
• temperature - average motion of particles in a substance
• conduction - heat transfer directly from one substance to another
• convection - movement in a gas or a liquid in which warmer parts move up and colder parts move down
• radiation - transfer of heat energy through empty space

Many thanks to Jim Clark for this idea.

## Procedure

### Part I  Conduction

Assist students to carefully pop popcorn on a hot plate or stove using canola oil.

#### Steps:

1. Students should use gloves and goggles.  They should be warned of the danger of a hot plate or stove and supervised carefully.
2. Add 3 Tbsp canola oil to the 3-Qt Saucepan
4. Turn on the hot plate to medium high, cover the saucepan, and place it on the stove.
5. Wait for the saucepan to heat up
6. Hold the saucepn carefully by the handle and shake it as the kernels pop.
7. Remove from the heat and allow to cool when popcorn is popping only every second or two.

#### Discussion of Conduction

1. While waiting for the pan to warm up, discuss heat transfer by conduction - through a solid material.
2. Ask:  "What is conducting the heat in this case?"  the pan
3. Ask:  "Why is the popcorn heating up?"  It is in contact with the oil, which is in contact with the pan, which is in contact with the stove (or hot plate).
4. Discuss and allow questions.

### Part II  Convection

Students will pop popcorn in an a popcorn popper.   These were less difficult to find than we thought they would be.

#### Steps:

1. According to the directions with the popper, place the popcorn kernels in the popper.
2. Turn on the popper.
3. Hot air will transfer heat to the kernels, making them expand and pop.

#### Discussion of Convection

1. Ask:  "What is heating the popcorn?"  the hot air in the popcorn popper
2. Describe to students why this models convection:  The hot air transfers the heat to the cooler kernels, and when enough hot air heats the kernels, they pop.
3. Discuss and allow questions.

1. Students will pop popcorn in a microwave.
2. Ask:  "How was the popcorn heated in the microwave? What is heating it?"  Radiation- energy transfer through empty space

1. The kernels are heated by the radiation in the microwave, and the kernels heat up, giving off more heat to the kernels surrounding them.
2. Tell students that radiation is the main manner in which air is heated by the Sun.

### Part IV Closure

1. Enjoy popcorn in three groups - the conduction, convection,and radiation groups.
2. Students review using vocab cards if so desired. (See variations.)

## Variations

• Vocab review cards can be made to review either as a game or for individual review.
• See link to vocab review game.

## NGSS Standards:

PS3.A: Definitions of Energy

• The faster a given object is moving, the more energy it possesses. (4- PS3-1)
• Energy can be moved from place to place by moving objects or through sound, light, or electric currents. (4-PS3-2),(4-PS3-3)

PS3.B: Conservation of Energy and Energy Transfer

• Energy is present whenever there are moving objects, sound, light, or heat. When objects collide, energy can be transferred from one object to another, thereby changing their motion. In such collisions, some energy is typically also transferred to the surrounding air; as a result, the air gets heated and sound is produced. (4-PS3-2),(4-PS3-3)

PS3.A: Definitions of Energy

• The term “heat” as used in everyday language refers both to thermal energy (the motion of atoms or molecules within a substance) and the transfer of that thermal energy from one object to another. In science, heat is used only for this secondmeaning; it refers to the energy transferred due to the temperature difference between two objects. (secondary to MSPS1- 4)
• The temperature of a system is proportional to the average internal kinetic energy and potential energy per atom ormolecule (whichever is the appropriate building block for the system’s material). The details of that relationship depend onthe type of atom or molecule and the interactions among the atoms in the material. Temperature is not a direct measure of asystem's total thermal energy. The total thermal energy(sometimes called the total internal energy) of a system dependsjointly on the temperature, the total number of atoms in the system, and the state of the material. (secondary to MS-PS1-4)

#### Middle School - Energy

• Temperature is a measure of the average kinetic energy of particles of matter. The relationship betweenthe temperature and the total energy of a system depends on the types, states, and amounts of matter present. (MS-PS3-3),(MS-PS3-4)

PS3.B: Conservation of Energy and Energy Transfer

• When the motion energy of an object changes, there is inevitably some other change in energy at the same time. (MS-PS3-5) The amount of energy transfer needed to change the temperature of a matter sample by a given amount depends on the nature of the matter, the size of the sample, and the environment. (MS-PS3-4)
• Energy is spontaneously transferred out of hotter regions or objects and into colder ones. (MS-PS3-3)

PS3.C: Relationship Between Energy and Forces

• When two objects interact, each one exerts a force on the other that can cause energy to be transferred to or from the object. (MS-PS3-2)