Summary

In this lab, students will experience several examples of energy transfer. They will analyze their observations and interpret their results in an attempt to explain why each transfer took place.

Grade Level

Middle and High School

NGSS Alignment

This lab will help prepare your students to meet the performance expectations in the following standards:

• MS-PS3-4: Plan an investigation to determine the relationships among the energy transferred, the type of matter, the mass, and the change in the average kinetic energy of particles as measured by temperature of the sample.
• 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.
• HS-PS3-1: Create a computational model to calculate the change in the energy of one component in a system when the change in energy of the other component(s) and energy flows in and out of the system are known.
• HS-PS3-4: Plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperatures are combined within a closed system results in a more uniform energy distribution among the components in the system.
• Scientific and Engineering Practices:
  • Analyzing and Interpreting Data
  • Constructing Explanations and Designing Solutions

Objectives

By the end of this lab, students should be able to:

• Determine the flow of energy transfer in a given situation.
• Discuss the kinetic energy of particles in relationship to thermal energy.
• Explain their observations with justified reasoning.

Chemistry Topics

This lab supports students’ understanding of

• Energy Transfer
• Heat
• Temperature
• Particle Motion

Time

Teacher Preparation: 30 minutes

Lesson: 1 hour

Materials

• Desk(s) made of wood and metal
• 3 labeled containers/buckets containing water (warm, room temperature and cold)
  • Multiple set-ups of this would be helpful
• Balloons
  • 1 inflated with air
  • 1 inflated, but containing water
  • Several extra balloons
• Bunsen Burner
  • Alternative option: candle
• Small piece of copper
• Beaker or small container with water
• (optional) Thermometer(s)

Safety

• Always wear safety goggles when handling chemicals in the lab.
• Always use caution around open flames. Keep flames away from flammable substances.
• Always be aware of an open flame. Do not reach over it, tie back hair, and secure loose clothing.
• When lighting the match and wooden splint, be cautious with the flame.
• An operational fire extinguisher should be in the classroom.
• Students should wear proper safety gear during chemistry demonstrations. Safety goggles and lab apron are required.

Teacher Notes

• This lab can be set-up/completed as stations (activity 1, 2 and 3). Activities 4, 5 and 6 need to be completed as teacher-lead demonstrations.
• Setting up multiple stations of each activity (1, 2 and 3) would be helpful for management/student wait time.
• This lab is best done with students placed in small groups of 3 or partners.
• Several talking/discussion points and expected results for some of the activities are included below for teacher consideration.
• Activity 1: Students place one hand on a wooden desktop and one hand on a part of the desk that is metal.
  • Most students will report that the metal feels colder. How is this possible if both the desktop and the metal are at the same temperature? The metal is pulling more energy from your hand (The heat transfer from your hand to the metal is more efficient.)
• Activity 3: Students place one hand in warm water and the other in cold water and then at the same time move both hands into the room temperature water.
  • At the beginning, both hands are at different temperatures (or the water molecules are moving quickly on the warm hand and the water molecules on the cold hand are moving slowly). What happens to the speed of the water molecules on both hand when they are placed in the room temperature water? How does each hand feel? Which way is the energy transferring? The fast-moving water molecules from the warm hand transfer energy to the room temperature water, so the hand feels colder. The slow-moving water molecules on the cold hand absorb energy from the room temperature water, the transfer of energy in this case is moving from the room temperature water (faster moving molecules) to the cold hand. As a result, the cold hand starts to feel warmer. At some point, the two hands will feel like they are at the same temperature, since both hands are at thermal equilibrium.
• Activity 4 and 5: An air-filled balloon will be heated over a Bunsen burner flame (activity 4). A water-filled balloon will be heated over a Bunsen burner flame (activity 5).
  • The balloon filled with just air will pop, but the other balloon, containing water should not pop due to the thermal energy transfer from the flame to the water inside.
• Activity 6: A piece of copper will be heated in a Bunsen burner flame. The glowing hot metal will be dropped into a beaker of room temperature water.
  • Why does the temperature of the metal drop 100+ of degrees while the temperature of the water only goes up 10’s of degrees? The concept here is differences in the specific heat capacity of the metal and water. Sharing the value for the specific heat of water with students can be helpful. It requires 4.18 J of energy to raise 1 g of water 1 degree Celsius or it requires 1 calorie of energy to raise 1 g of water 1 degree Celsius. Additionally using a thermometer to show the actual starting and ending temperatures of the metal and the water would be beneficial if available.
• (Optional) Depending on the ability or grade level of students, teachers may wish to integrate the use of particle diagrams to represent the motion and transfer of energy of the water molecules before and after energy transfer. The faster moving (higher energy) water molecules can be represented by particles with longer arrows. The slower moving (lower energy) water molecules can be represented by particles with shorter arrows. This allows students to conceptually represent a very abstract concept qualitatively without introducing numbers until a later point in time.
• An answer key for the student handout has been provided for teacher reference.