Qualitative Analysis Lab

Abstract Chemically active extraction was used to separate two unknown compounds from each other and to determine what compound class each compound belongs. The solid unknown was purified by recrystallization and its melting point range was determined to be 109-111°C. The liquid unknown was purified by simple distillation and its boiling point was determined to be 95°C. An IR spectrum was collected for each of the purified compounds; the solid was determined to be 3-toluic acid and the liquid was determined to be 2-heptanone.

Introduction Extraction is one way of purifying a substance. In an extraction, a solute is transferred from one solvent to another. Extractions depend on polarity and solubility; polarity is the separation of charge caused by a difference in electronegativity, and solubility is the ability of a material to dissolve into another physical phase. There are three types of extractions: solid-liquid, liquid-liquid, and chemically active (or acid-base).1 In a solid-liquid extraction, solvent is added to a mixture of solids and any solids of similar polarities will dissolve into the solvent. In a liquid-liquid extraction, two solids are separated by using two solvents of opposing polarity. Chemically active extractions are when two nonpolar materials are in solution, and one is chemically changed in order to change its polarity. In order to get the best yield, it is important to perform many small extractions rather than one large extraction. This is because some solubility in one layer will cause an equilibrium reaction between the organic and aqueous layers. Performing several smaller extractions will provide more opportunities to separate the components. A separatory funnel can be used for a chemically active extraction. Recrystallization is a method of purification. Many substances are impure and require purification in order to obtain the desired product. There are three steps involved in recrystallization: dissolving the material