In this lesson students will be introduced to simple distillation while expanding their knowledge of intermolecular forces. Once a simple distillation has been accomplished in the lab, students will then research the various products of fractional distillation of crude oil and report on one of those products.
This lesson will help prepare your students to meet the performance expectations in the following standards:
- HS-PS1-3: Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles.
- HS-ETS1-1: Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.
- HS-ETS1-3: Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.
- Scientific and Engineering Practices:
- Analyzing and Interpreting Data
- Obtaining, Evaluating, and Communicating Information
AP Chemistry Curriculum Framework
This demonstration supports the following learning objectives:
- Big Idea 2: Chemical and physical properties of materials can be explained by the structure and the arrangement of atoms, ions, or molecules and the forces between them.
- 2.10 The student can design and/or interpret the results of a separation experiment (filtration, paper chromatography, column chromatography, or distillation) in terms of the relative strength of interactions among and between the components.
- 2.13 The student is able to describe the relationships between the structural features of polar molecules and the forces of attraction between the particles.
- 2.16 The student is able to explain the properties (phase, vapor pressure, viscosity, etc.) of small and large molecular compounds in terms of the strengths and types of intermolecular forces.
By the end of this lesson, students should be able to
- Conduct a distillation experiment.
- Describe the relationships between the structural features of polar and nonpolar molecules and the forces of attraction between the particles.
- Explain the properties of small and large molecular compounds in terms of the strengths and types of intermolecular forces.
- Explain the process of fractional distillation and the products from crude oil that are produced.
This lesson supports students’ understanding of
- Separation Techniques
- Intermolecular Forces
- Non-Polar Molecules
- Hydrocarbon Molecules
- Engage: 10-30 minutes.
- Explore: 50 minutes
- Explain: 30-35 minutes
- Elaborate: 1 to 2 hours (assign additional time as homework if needed)
- Evaluate: 1 to 2 hours
Teacher Led Saltwater Distillation Demonstration
- Electronic Scale
- Conductivity Meter
- Saltwater Solution for distillation (~3.5 g in 100 mL of water)
- Saltwater Solution in beaker for conductivity test
- Water (control sample) for conductivity test
- Flasks (Distillation flask is best, but can use others if needed)
- Condenser ( if not available you can put distillate flask in ice bath or run tubing through ice bath)
- Heat Source (Bunsen burner or hot plate)
- Double-holed rubber stopper
Student Lab Investigation Materials
(per lab group)
- Test tube rack
- Ice Bath (600 mL Beaker w/ ice)
- Cherry Coke
- 250 mL Erlenmeyer Flask
- Hot Plate
- 50 mL Graduated cylinder
- Two-hole rubber stopper
- 2 Test tubes
- Bent glass tubing
- Rubber tubing
- Boiling chips
- 2 Ring Stands
- Test Tube Clamp
- Always wear safety goggles when handling chemicals 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.
- Always use caution around open flames. Keep flames away from flammable substances.
- Exercise caution when using a heat source. Hot plates should be turned off and unplugged as soon as they are no longer needed.
- Students should wear proper safety gear during chemistry demonstrations. Safety goggles and lab apron are required.
- This resource could be used as a post-AP Chemistry exam activity.
- Engage: Students should have a basic understanding of intermolecular forces and polarity before this lesson begins. Begin the class by showing this Simpson's clip Water Water Everywhere. Discuss Water Facts of the world from Water.org. Facilitate discussion of ocean water as a source of drinking water. Have saltwater distillation set up. Dissolve 3.5 grams per 100 mL of water. 100-200 mL of saltwater solution is sufficient. While distillation is occurring, have another solution of saltwater made in a beaker along with a control sample of water from a tap source. Collect conductivity data of the two samples. Once the distillate has been collected, compare its conductivity to the other two. Review the process of boiling and condensing within the framework of intermolecular forces of the water. The teacher should set-up the distillation apparatus prior to class.
Explore: Once the demonstration has been completed, students and teacher should discuss the cherry coke distillation. This investigation will be a qualitative introduction to the idea of fractional distillation. Students will heat a sample of cherry coke and witness three different fractions. The first will be carbon dioxide and will be run through limewater to show a precipitation reaction for positive identification. Second, the flavoring esters will be collected and finally sugar water will be collected. The temperature of the liquid in the flask should never exceed 100 oC. Professional distillation equipment can be used if available, otherwise an Erlenmeyer flask with a hot plate can be substituted. Before the students conduct the experiment, check all of the setups to make sure all connections are tightened. See video: Lab Set Up for reference. Lab handout and instructions for students are provided. Limewater should be prepared by the teacher in advance of the lab.
Explain: Now that the students have witnessed a fractional distillation, the concept will be shown on an industrial scale with the fractional distillation of crude oil. Begin the explanation portion of the lesson with a review of polarity and intermolecular forces. London dispersion forces (LDF’s) and the idea of polarizability should be emphasized for the students to understand how the hydrocarbons are separated out of the crude oil. Showing the students a sample of solid fat and vegetable oil could be used as evidence of the ideas discussed. Videos can then be shown that summarize the ideas of fractional distillation and the cracking of hydrocarbons. Show the Fractional Distillation video first, followed by the Hydrocarbon Cracking video. Each of the videos are about four minutes long. This Real World Fractional Distillation video clip is also beneficial for students to see.
Elaborate: The project portion will now be introduced to the students. The research project will have four different components. First, students will further research the process of fractional distillation of crude oil and the cracking of hydrocarbons. Second, students will choose a specific distillate (refinery gas, petrol, naphtha, kerosene, diesel oil, residue, etc.) and research its properties, uses, and any other information that the students find interesting. Third, students will then choose a fossil fuel, possibly created by their distillate, and research it properties, uses, and by-products. E85 can be added to this section as well. Finally, students will choose an alternative fuel and research it properties, uses, production, and the feasibility of replacing fossil fuel.
Evaluate: Students will be evaluated on two separate artifacts. First, they will present all of their research to the class. The use of technology in their presentation will be expected. A slide slow, multi-media presentation, or recorded video could be used for the presentation. Any other ideas should be approved by the instructor. Second, in addition to the presentation, the students will write a research paper with cited sources. Depending on the number of students or groups, one to two class periods will need to be set aside for their presentations. As each teacher’s grading policy and techniques are very different no rubric was created, however, a teacher created rubric could be used for all groups.
Extension and Differentiation Ideas
The following could be used to change the rigor of the activities to fit the level of the students in the classroom
- Students work in groups of 2, 3, or 4.
- Students complete project individually.
- Assign each group member a specific role to fulfill.
- Assign the groups each of their research topics.
- Require use of a peer reviewed journal for the paper.
- Depending on student resources, research can be completed during class time or outside of school.
- At the end of the Cherry Coke distillation, if your students are familiar with the Benedict’s test for sugars, I would suggest adding it in to link the lab with other learning.