Essay about Thin Layer Chromatography Lab Report

1793 Words Dec 24th, 2012 8 Pages
OBJECTIVE
The purpose of this experiment is to analyze mixtures of compounds prior to, during and after a separation scheme. This experiment also allows monitoring reactions of organic molecules, and determines the identity of a mixture of compounds.

STRUCTURES AND PHYSICAL PROPERTIES OF REACTANTS

[1] SOLVENTS | a. Hexane1Molecular Molarity: 86.18 g/molBoiling Point: 69 ºCMelting Point: -95ºCDensity: 0.659 g/mL at 25ºCWater Solubility: Insoluble in waterColor/Texture: Colorless/LiquidHazardous Information: May cause irritation to the eyes, skin and respiratory system. May cause drowsiness and/or dizziness. Suspected of damaging fertility or unborn child. May cause damage to organs. Toxic to aquatic life. Highly flammable liquid and
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The plates were set aside to dry and then visualized under short-wave lamp to locate and circle the spots. An acceptable eluting solvent is one that gives 3 distinct spots, therefore, methylene chloride was chosen.
Determination of the Identity of an Unknown
A large silica gel TLC plate was obtained and checked for contamination. A light line was drawn across the plate approximately 4mm above the bottom edge with four “X” marks along the line. A spot of biphenyl solution was placed on the first “X”, a spot of Benzophenone solution was placed on the second “X”, a spot of Benzhydrol solution was placed on the third “X” spot and a spot of the unknown was placed on the last “X”. The letter of the unknown was recorded in the lab notebook as. The spots were visualized under a UV lamp to ensure enough solution was present at each “X” mark. The plate was then eluted in a 400mL beaker of methylene chloride prepared similar as the above eluting chambers. Once the solvent traveled about ¾ up the TLC plate, it was removed and the front of the solvent was marked. The plate was left aside to dry then viewed under a UV lamp in order to mark the spots visualized. The Rf value of all 3 known solvents and the unknown were measured using a centimeter measurements of a ruler and calculated using the following equation:
Rf value = Distance traveled by the solute…

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