Identifying Organic Compounds Lab

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Mrs. Feeney
Biology 9
October 16, 2012
Identifying Organic Compounds
Objective:
To use indicators to test for the presence of organic compounds in certain substances.

Theory:
Major types of organic compounds in some common foods are Lipids, Carbohydrates, and Proteins. An indicator is a chemical compound that changes color and structure when exposed to certain conditions and is therefore useful for chemical tests. The purpose of using distilled water as one of the substances in the test is that it’s the control; it should never be positive since it has no organic compounds. The control group in part c is the 5 Ml of distilled water.

The purpose of washing the test tubes thoroughly is so you don’t mix substances, which can cause your results to be inaccurate. Hypotheses:
1. If the test samples contain Protein, then in the presence of Biuret the color will turn to yellow, green, or lavender. 2. If the test samples contain Carbohydrates, then in the presence of Benedict’s color will turn to “traffic light colors” which consist or orange, red, yellow, and sometimes green. 3. If the test samples test positive for starches, then in the presence of Iodine, their colors if the test sample contains sugars, then the iodine will change from yellow-brown to blue-black. 4. If the test samples show the presence of lipids, the when the substance is placed onto a brown paper bag and sits for 10 minutes, then a translucent or opaque spot will appear. Materials:

* 8 test tubes
* test tube rack
* test tube holder
* glass stirring rod
* sharpie marker
* how water bath
* iodine solution
* brown paper bag
* Biuret reagent
* benedicts solution
* 20 ml each:
1. honey solution
2. egg white and water solution
3. gelatin and water solution
4. melted butter and water solution
5. apple juice and water solution
6. distilled water
7. unknown solution
Procedures:
PART A: TESTING FOR LIPIDS...
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