Lesson List
A Five-Module, Discovery-Based Unit to Teach Separation Science in a High School Chemistry Class
Analytical Problem Solving
Chromatography Is a Gas: Inquiry-Based Introduction to Gas Chromatography
Designer Colors, an Inquiry Approach to Flame Testing
Introduction to the Mole
Investigating Plant Pigments: A Guided Inquiry Laboratory Experiment
Separation Science Lab: An Inquiry-Based Lab
Lesson Descriptions |
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| A Five-Module, Discovery-Based Unit to Teach Separation Science in a High School Chemistry Class |
There are several methods of separating and identifying compounds. These techniques range from the simple paper chromatography to thin-layer chromatography (TLC) to gas chromatography to distillation to high performance liquid chromatography (HPLC) to the newest super critical fluid chromatography. A scientist would choose a separation technique based on the substances to be separated and the desired quantitative accuracy. Coupled with the separation must be a detection technique to observe and identify the separated fractions. These detection techniques range from visual colorimetric identification to spectrophotometric identification to mass spectrophotometric identification. The choice of detection technique depends on the separation technique.
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Analytical Problem Solving
This set of activities uses a "just in time" principle of parceling information and supplies to students in an analytical chemistry course. The idea behind this approach is that students have time to think about the questions posed, and if necessary, find information from other sources. This makes them active participants in the learning process. Before the students begin the laboratory activity, they receive a brief introduction to the topic to be studied that raises questions to think about before entering the lab, discusses a real-world issue related to the chemistry topic, or reviews specific safety or procedural considerations. No theoretical introduction is provided since the intent of the approach is to lead students to figure out the concepts for themselves. During the lab, students are given only the necessary information when they need it and ask for it, and they discover for themselves what information and factors are extraneous. Students must decide what their needs are for each activity and then request specific chemicals or equipment. They learn to use available analytical instruments as needed for each activity.
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Chromatography Is a Gas: Inquiry-Based Introduction to Gas Chromatography
This chromatography exercise was designed to introduce students to the theory of chromatographic separation of mixtures and packed column chromatography. The students will become familiar with basic operation of the gas chromatograph and explore the relationship between temperature and retention time of individual components in a mixture. A section on instrument trouble-shooting may be included as an additional optional activity.
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Designer Colors, an Inquiry Approach to Flame Testing
In place of traditional flame test procedures, the students will make lances (small tubes that hold the materials for color testing), make a spectroscope to observe the flames from the burning lances, and create a specific, reproducible color.
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Introduction to the Mole
This unit uses a discovery-based method to introduce the mole concept without relying on students’ strong background. The lessons contain activities with candy that lead students to develop the rules for mole-item, item-mole, mole-mass, and mass-mole "conversions." Experiences that engage different types of learners are utilized to reinforce the concepts. The unit provides students with opportunities to make the connection between the mole concept and familiar counting units, such as a dozen, and apply the concept of the mole to measuring out a given quantity of a substance.
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Investigating Plant Pigments: A Guided Inquiry Laboratory Experiment
This experiment includes traditional methods of laboratory instruction as well as guided inquiry. The first part of the experiment teaches basic laboratory techniques of column chromatography, including the packing of a column, sample application, elution methods, and variations of these techniques. This portion is presented in a routine method of directed work to be sure the students understand the basic premise of column chromatography. After the students have successfully completed Part I of the experiment, the method switches to discovery or guided inquiry. In Part II, the students will design an experiment to separate the components of a pre-prepared leaf extract. The students will be provided with a variety of packing materials, different solvents, and the necessary equipment. Part III extends the experiment to detection and identification of the components separated in Part II.
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Separation Science Lab: An Inquiry-Based Lab
In this inquiry-based experiment the students are put in the role of a method development chemist. The scenario they are given is that a train wreck has occurred which resulted in a chemical spill. They are told that the spill mixture consists of three substances: a proprietary chemical called CARBOSE (simply sodium chloride), naphthalene, and sand from the dry Florida riverbed where the accident took place. The students work in teams of 23 and the team’s task is to design a method to separate the three components of the mixture in the most efficient, cost-effective manner possible. In addition, their method must allow them to recover the CARBOSE in the solid form. The lab is divided into three parts and should be spread out over two lab periods to allow students time to collect data and reflect on questions.