Liquid-Liquid Extraction Essay

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LIQUID-LIQUID EXTRACTION OF BENZOIC ACID J Wright Organic Chem Lab 1 Tuesday 1:40-5 Ian Stubbs LIQUID-LIQUID EXTRACTION OF BENZOIC ACID PURPOSE: The purpose of this experiment was to extract benzoic acid from an aqueous of benzoic acid using methylene chloride, use liquid-liquid extraction to calculate the distribution coefficient of benzoic acid and to determine whether a single extraction or multiple extractions are more efficient. Add in the table of physical constants. See the attachment for the lab format. PROCEDURE: Gather a two stock solution that includes; 0.02M of sodium hydroxide (NaOH) aqueous solution and 0.02M of benzoic acid aqueous solution. For a single extraction, use a 50mL graduated cylinder and measure out 50mL of the benzoic acid solution into a 125mL separatory funnel. Add 10mL of methylene chloride (dichloromethane or CH2Cl2 for abbreviation which is the organic layer), the extracting solvent, to the funnel. Shake the funnel for thirty seconds pointing it away from the student and self. Release gas buildup by opening the stopcock of the separatory funnel. This is called the shaking and venting procedure. This procedure allows the benzoic acid (benzoic is the solute) to establish an equilibrium between the two layers the organic layer and the aqueous layer. Benzoic acid, although it has dissolve in water, is not very soluble in water (it will only dissolve in water at elevated temperature). However, benzoic acid is more soluble in methylene chloride. That is why once you add the benzoic acid aqueous solution and the CH2Cl2 in the separatory funnel the benzoic acid moves from the aqueous layer into the methylene chloride organic layer. This will occur until an equilibrium is establish between the aqueous layer and the organic layer; that is there is an equal amount of benzoic acid in the aqueous layer and the organic

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