Identification of Organic Compounds
History: We have five containers of unknown substances. The substances are Organic
Compounds. We poured the substances into five small beakers and labeled them
Unknown #1, #2, #3, #4 and #5.
Problem: We want you to identify these compounds as a protein, starch, glucose or lipid,
so we have provided four indicators to help you. They are as follows: Benedicts Solution,
Biuret, Iodine and Sudan III.
Procedure:
I. Put a small amount of unknown solution # 1 into each of the 4 test tubes labeled
“A, B, C & D”.
a) In test tube “A” add 3 – 5 drops of Benedicts Solution... turquoise blue in color.
Heat the test tube in a hot water bath to determine the presence of Glucose.
Orange color after heating will mean a positive result.
b) In test tube “B” add 3 - 5 drops of Biuret...blue in color. Turning violet indicates a
positive result. This will identify the presence of Proteins.
c) In test tube “C” add only 2 drops of Iodine... dark brown or reddish in color. This
will identify the presence of Starch. Very dark green-blue color (almost black) will
mean a positive result.
d) In test tube “D” add 3 – 5 drops of Sudan III... red in color. This will determine
the presence of Lipids. A dark red color ring of oil will indicate a positive result.
II. Record your results on the chart given to you.
III. Clean test tubes thoroughly using a test tube brush and repeat using unknown
solution # 2.
IV. Repeat until you can identify each unknown solution. (1 – 5)
IMPORTANT LAB NOTES...
1) Use the test tubes and don’t fill them more than 2cm.
2) Use 3 to 5 drops of the indicators, (except iodine only 2 drops).
3) DO NOT HEAT THE CHEMICALS THAT DO NOT NEED TO BE HEATED.
4) Do not contaminate the samples. Pipettes are labeled 1 – 5.
5) Wash all the test tubes with a test tube brush when done with specific tests.
6) Clean your station and put clean test tubes up-side-down on the posts to dry.
Identification of Organic Compounds Lab
Directions:
Complete the following chart based on your findings today in the lab. Please write a brief description of the
appearance of each solution tested and indicate whether the test results were positive (+) or negative (-). Each person
needs to complete this.
Hypothesis
Unknown Solution
#1
___________
Unknown Solution
#2
___________
Unknown Solution
#3
___________
Unknown Solution
#4
___________
Unknown Solution
#5
____________
Test results (color
of solution) from
Benedicts
Solution
Test results (color
of solution) from
Biuret
Test results (color
of solution) from
Iodine
Test results (color
of solution) from
Sudan III
___________
__________
___________
__________
Identification of
compound. Based
on your tests
results, was the
compound
glucose, starch,
protein or lipid?
The compound
was a
____________
The compound
was a
____________
The compound
was a
____________
The compound
was a
____________
The compound
was a
____________