Separating Chemicals

A report of an experiment designed to determine the best mixture of acetone and hexane that would be best to use when extracting lipids from plant leaves.

Separating Chemicals

Author: John McGowan

Lab Partners: Chelsea Brown, Peter Gardner, Susan Frazier

Instructor: Joel Jorolan

Chem 151, Section 54

Date Work Performed: September 8th, 2009

Date Work Submitted: September 15th, 2009

Introduction

The objective of the experiment was to determine the mixture of acetone and hexane that would produce the best results when extracting lipids from plant leaves. Before we began the experiment we expected that the best mixture would use both hexane and acetone; however, there were no preconceived notions as to the actual combination that would work best.

Our theory was that lipids would be pushed along a stationary medium by the hexane-acetone mixture and the different lipids would have different attractions to the stationary medium. The difference in attraction would cause the different lipids to move along the medium at different speeds, causing them to separate from each other. The difference in attraction is caused by a difference in molecular forces between the particles. This theory is known as TLC or thin layer chromatography because we use a thin layer of a substance to perform a chromatographic experiment.

In the experiment we crushed spinach leaves to break the cell walls and then used hexane and acetone to extract the lipids from the cells. After extraction we decanted the liquid into a beaker for use in the experiment.

Results

hexane 50%, acetone 50%

Color

Location (cm)

Yellow

3.41

Light green

5.41

Dark green

6.00

Hexane 40%, acetone 60%

Color

Location (cm)

Dark green

0.75

Light green

4.10

Yellow

7.00

Hexane 70%, acetone 30%

Color

Location (cm)

Yellow

0.50

Green

1.00

Yellow

7.60

Hexane 30%, acetone 70%

Color

Location (cm)

Yellow

6.40

Green

8.20

Calculations

Percentage of substance = substance/total (40% hexane of mixture = 4mg hexane/ 10mg (hexane-acetone mixture)

Retention factor = distance of tested chemical / distance of solution

Discussion

From the results gathered it seems that a mixture of 40% hexane and 60% acetone would be the best solution to use when separating lipids. I came to this conclusion because the 40/60 mixture (40% hexane, 60% acetone) produced a result with the farthest spread lipids. The solution that worked the least was the 30/70 mixture (30% hexane, 70% acetone) because it only produced two different lipids rather than three.

Though our results lead to this conclusion, to be certain of our conclusion we would need to perform many more tests. The data we collected was unreliable due to several circumstances. One reason for the unreliable data is because the stationary material was tainted by cracks and broken edges which caused the lipids and solution to take undesired paths towards the top of the material. This caused the lipids to end up in different places then expected. Another issue was that we were only able to take one test for each solution, for better results we would need to retest each solution multiple times to be sure to get the same results. Finally, we didn’t test other solutions, only those listed under the results section. To find the best solution we would need to perform many more tests on different combinations of the two substances.

0
Liked it
No Responses to “Separating Chemicals”
Post Comment
comments powered by Disqus