In this lesson students will analyze the effectiveness of different brands of antifreeze/coolants and their ability to protect an engine in cold climates. Students will conduct a lab investigation to examine the freezing point depression in samples that have been diluted with distilled water. Students will also determine the specific heat capacities of antifreeze/coolant products as compared to pure water and explain how it relates to thermal energy transfer in the internal combustion engine.
- HS-PS1-1: Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
- HS-PS3-4: Plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system (second law of thermodynamics).
By the end of this lesson, students should be able to:
- Draw conclusions from experimental data in which they compare and contrast different antifreeze/coolant products.
- Support conclusions with valid arguments based on experimental evidence.
- Explain the process by which an internal combustion engine is cooled.
- Relate the cooling process to thermal heat transfer and heat capacity.
This lesson supports students’ understanding of:
- Colligative properties (freezing point depression)
- Specific heat capacity
- Thermal energy transfer
Teacher Preparation: 30-45 minutes
- Engage: 60 minutes
- Explore: 2 hours
- Explain: 30 minutes
- Elaborate: 30 minutes
- Evaluate: 60 minutes
- 4 Different brands of antifreeze/coolant (full strength)
- Thermometer or temperature probe with appropriate computer interface
- 100-mL beakers
- Ring stand and clamps
- 100-mL graduated cylinders
- Rock salt
- Crushed ice
- Stirring rods
- Nalgene or other non-glass beaker
- Electronic balance
- Always wear safety goggles and aprons when handling chemicals and glassware in the lab.
- Students should wash their hands thoroughly before leaving the lab.
- When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
- Ethylene glycol SDS
- Propylene glycol SDS
- This resource could be used as a post-AP Chemistry exam activity.
- Engage: Essential questions should be presented to students:
How does the cooling system in an internal combustion engine work?
- Students will be given a diagram that illustrates how the cooling system works in an internal combustion engine.
- Students write a brief explanation of the purpose for each component.
- What is the best antifreeze/coolant for an automobile engine? What criteria should be considered when selecting one brand over another?
- On the first day of the lesson, students will be presented with a request from an automobile dealer in northern Vermont to analyze different brands of antifreeze/coolant so that they can make recommendations to their customers.
- Students will engage in a brainstorming session in which they will identify key factors to consider when selecting an antifreeze/coolant product.
- How do products containing propylene glycol compare with those made with ethylene glycol?
- Students will research the properties of both compounds and prepare a table of advantages/disadvantages or pros/cons of each one.
- Explore: Students perform both of the included lab investigations.
- Explain: Students will discuss and analyze experimental findings from investigations.
- Elaborate: Students will integrate essential questions and initial research into a coherent explanation of their experimental findings.
Evaluate: Student groups will prepare and submit a product, in the format of their choosing to present their experimental findings and make the connection to the cooling system in an internal combustion engine. (For example: Students could produce a narrated pictorial account of their investigation, a video, or commercial that advertises the product that gave the optimal results).
- This information focused on the history of the Water Cooling System in Model T Ford engine may be helpful for a teacher to review before the lesson.
- This diagram of a cooling system may be helpful to share with students.