Searching for Physical and Chemical Properties of Organic Compounds

Lesson Plan

Audience and Context

The audience for the lesson is sophomore and junior chemistry majors, other science majors, and pre-health students who are taking the Organic Chemistry Lab. There are 15-20 students within a lab section, but multiple lab sections meet at once meaning that it will be necessary to instruct about 80-100 students at once. This will make hands-on aspects a little more difficult than it would be for one section of a lab.

Content

I will be presenting information on how and where to search for physical properties of different chemical compounds in handbooks and on the web. Students in organic chemistry labs need to be able to locate the properties of the different compounds they will be working with in their labs in order to help them identify unknown compounds and to check their own results. These properties include molecular weight, density, solubility, melting or boiling points, and color.

Learning objectives

Upon completing this session, students will be able to:

• Identify 1 print source and 1 electronic source for physical property data for organic compounds.
• Successfully locate pertinent physical data for compounds necessary for preparing for organic chemistry labs.
• Understand that no single source will have all the information a chemist needs.

Assessment technique

For their first lab, students will need to come prepared with the physical properties information for the compounds they will be using in their lab. In addition to the usual information they provide (formula, molecular weight, melting or boiling point, and solubility), students will be asked to include the CAS registry number and source of their information for each compound. They will need to use at least one print source.

Class agenda

• Introduction (5 minutes)
• Introduce myself
• Give brief description of purpose of session
• Ask students where they would find the boiling point of benzene
• Give comparison between number of chemical substances (over 35 million) and number of compounds indexed by ChemFinder.com (about 75,000) to illustrate why it is important to be familiar with multiple sources
• Searching for compounds (20 minutes)
• Have students vote on which compounds to search for ChemFinder.com demonstration
• Cinnamaldehyde (from cinnamon)
• Theobromine (from chocolate)
• Vanillin (from vanilla)
• Demonstrate three common methods of searching for compounds
• Chemical name
• Go over relevant parts of record and ask what questions they have about record
• Ask students how else they can find a compound
• Molecular formula
• Show how many compounds can have same formula
• Make sure they are familiar with Hill System of Ordering
• Carbon first, hydrogen second, then alphabetical order of elements
• CAS (Chemical Abstracts Services) Registry Number (RN)
• Explain that CAS RN is like Social Security Number for molecule (i.e., unique identifier)
• Print resources for physical properties data (20 minutes)
• Give out handouts on caffeine from three different handbooks
• Dictionary of Organic Compounds
• Handbook of Data on Organic Compounds
• Merck Index
• Briefly describe each handbook
• Ask students for differences between the three entries for caffeine
• Ask students questions about different properties of caffeine and which source they used to locate it such as
• What is the CAS Registry Number of caffeine?
• What increases the solubility of caffeine in water?
• What is a synonym for caffeine?
• Wrap-up (5 minutes)
• Have my contact information on Power Point slide
• What questions do they have?

Resources and materials

I will provide a packet of handouts to the students that includes my Power Point presentation which will include a list of the print and electronic resources I will be discussing. Also included will be copies of the three different entries for caffeine on a single sheet.

Room arrangement and equipment needs

I will need a room with a computer with Internet access and PowerPoint.

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Created in partial fulfillment of the requirements for INLS 214: User Education.
Questions? Contact Meghan Lafferty at melaffer@email.unc.edu. Last updated July 5, 2003.