Difference Between Solubility Dependent Extraction And Recrystallization

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The motivation behind this experiment was to gain insight behind the theory and practice of two laboratory techniques: solubility-dependent extraction, and recrystallization, in an effort to isolate and identify three compounds originally dissolved in a mixture. Extraction is used to isolate a specific compound. Recrystallization involves taking a crude compound and removing unwanted impurities so that a more accurate melting point can be taken, leading to a more precise identification of a compound. The overarching goal was to isolate and identify three different unknowns in a given sample using these techniques. There are two types of extractions; solid-liquid extractions involve extracting a soluble compound from an insoluble (solid) material …show more content…
Upon vigorous mixture of original and extraction solvent, an optimization of physical contact (surface area) between the extraction solvent and desired compound drives the compound to migrate into the extraction solvent because of its more favorable solubility. There are four rules that dictate whether a chosen solvent can efficiently be used to extract a specific compound. For one, the original solvent and extraction solvent must be immiscible. If these solvents do mix, one will only make a more complex mixture that will be hard to separate. Secondly, the extraction solvent must not irreversibly react with the desired compound, this would decrease yield of product and result in an inefficient extraction. Thirdly, the extraction phase should selectively remove the desired compound; non-selectivity of the solvent could result in extracting multiple compounds. Lastly, the extraction …show more content…
The process of extraction also heavily weighs on the fact that compounds are more favorably soluble in a certain solvent based on solubility characteristics of the desired compound. There are four factors that determine the solubility characteristic of a compound: pH, temperature of the solvent, pressure of the system, and ionic character of solute. Ionic character and pH were manipulated to increase solubility favorability of the compound in extraction solvent. In essence, pH is the easiest factor to manipulate because it merely involves using an aqueous acid or base as an extraction solvent that simultaneously abides by the four solvent requirements of extraction. In regard to recrystallization, an impure compound is allowed to dissolved into a solvent and then allowed to reform as a pure solid because of the fact that the impurities of the crude sample are either fully soluble or insoluble in the solvent chosen. Three criteria must be met for this phenomenon to occur: the compound to be purified must be soluble in a relatively hot solvent, the compound to be purified must be

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