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Transcript of Chromatography Lab
The dot of food coloring or crime sample on the strip of chromatography paper represents the stationary phase. When the paper is placed in the test tube, the solvent is absorbed and moves up the paper, signifying the mobile phase. The intermolecular forces between the solvent and solute cause the dot to bleed up the paper with the solvent.
For our food coloring test we chose ethanol, acetone and distilled water. All solvents contain Oxygen and Hydrogen. We wanted to test the varying structures that shared these atoms in order to discover which combination of the O and H
atoms would best separate the dye.
The separation of the solvent depends on two things:
1. molecular mass
2. The solubility of a substance in the solvent
The higher the mass, the longer a molecule stays in the stationary stage, making it appear higher on the paper.
A lighter molecule will move to the mobile phase quicker, making it appear lower on the paper.
If both the substance and solvent are polar, this will aid the separation of the molecules.
Distilled water was the most polar.
Strong intermolecular forces between the compound and the solvent leads to a quick movement of the dye
Stronger intermolecular forces between the solvent and the paper will slow the movement of the dye
We hypothesized that distilled water would separate the colors the best. The O and H molecules are separate in the water molecules structure so it can combine more freely as opposed to the bonded O and H molecules of Ethanol and Acetone. Our data supported this hypothesis because the dye traveled furthest in the distilled water.
The dye enters the mobile phase at the point when it interacts with the water and visibly travels up the chromatography paper. The rate depends on the interaction between the molecules of the solvent and the compound.
The solvent with the best green chemistry in our experiment was acetone. With a short half-life, acetone does not pose a large threat to the environment unless it is disposed in large quantities by industry. It can, however, lead to oxygen depletion in large quantities in aquatic environments. Ethanol poses a list of environmental dangers including increasing air pollution, greenhouse gas emissions and water pollution.
The cellulose in the chromatography paper are polar, which attract the O and H atoms and assist in the separation of molecules, an intermolecular force