Experiment 13: Aldehydes, Ketones, Carboxylic Acids, and Esters
Part 1: Qualitative Analysis of Aldehydes and Ketones
In this assignment, you will be given an unknown compound for which you will need to identify as an aldehyde or a ketone based on the results of the chemical tests performed below.
1. Start Virtual Organic Chemistry Lab and select Qualitative Analysis - Aldehydes from the list of assignments under "Qualitative Analysis". You should be brought to the Qualitative Analysis laboratory, and on the reagent shelf you will find two or more compounds that serve as practice unknowns and another bottle that is your assigned unknown. When you are ready to analyze your unknown, click on the unknown bottle and add the syringe or scoop to the round bottom flask. Now drag the flask from the stockroom counter to the cork ring on the lab bench.
2. The round bottom flask containing the unknown should now be on the cork ring on the lab bench. The boiling point and C-H analysis for the unknown are listed on the chalkboard. If the unknown is a solid, the melting point can be measured by clicking on the melting point apparatus to the left of the lab bench and dragging the melting point tube to the unknown in the flask. The melting point will be displayed on the red LED, which can be enlarged by mousing over the apparatus. It will also be useful to know the polarity of the unknown by performing a TLC measurement. Record all of this information in the data table below.
Data Table Unknown Number:__________
C-H Analysis | Melting Point (°C) | Boiling Point (°C)
3. To perform the functional group tests, click on the unknown and drag a test tube containing the unknown to the clamp over the stir plate. You should see a picture of your unknown on the chalkboard. Now perform the Tollens test by clicking on the reagent bottle labeled Tollens reagent and drag the pipet to the test tube. The results of the test are shown on the chalkboard with either a picture or a short video clip. Record the results of the test as either positive or negative in the table below. (See your textbook for a description of the functional group tests.) Discard the test tube by dragging it to the red disposal bucket and repeat the procedure for the other functional group tests. Make sure to record all of your results in the table below.
Results for Functional Group Tests
Functional Group Test | Observations and Results (+ or -)
Tollens Test
Iodoform Test
4. Using the data you have now collected, determine the functional group of your unknown compound and report the name of the family below. Be sure to include your unknown number, which is shown on the chalkboard.
Unknown # _________ Family: _________________________________________________