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A Separation And Purification Scheme

Abstract:
Experiment 55 consists of devising a separation and purification scheme for a three component mixture. The overall objective is to isolate in pure form two of the three compounds. This was done using extraction, solubility, crystallization and vacuum filtration. The experiment was carried out two times, both of which were successful.

Background Information:
This experiment combined all the knowledge of the previous labs performed throughout the semester. An unknown mixture containing an organic acid or base and an organic neutral compound in nearly equal amounts needs to be separated to its separate components. An understanding of solubility, extraction, crystallization and vacuum filtration is necessary in order to successfully carry out the separation.
Solubility consists of a solute and a solvent. Elements that dissolve are “soluble” and elements that don’t dissolve are “insoluble”. If the components are two liquids, the terms “soluble” and “insoluble” are replaced with “miscible” and “immiscible”. The main guidelines in determining solubility are: 1. All hydrocarbons are nonpolar, 2. compounds containing the electronegative elements oxygen and nitrogen are polar, 3. halogens do not alter polarity, 4. adding carbons to a chain decreased polarity, 5. dipole-dipole interactions is the force of attraction between polar molecules (H-H bonds being the strongest), and 6. branching of compounds results in a greater solubility in water than the corresponding straight chain compound.
Extraction is the method of mixing a solution with a second solvent that is immiscible with the first solvent. The two liquids then form two distinct layers (phases) that can easily be separated from one another. After each extraction, tests can be done on each layer to identify the products.
Crystallization is the process of forming solid crystals from a uniform solution. A dissolved substance with a decreased solubility at a lower temperature will...