Separations and Purifications . *** Flashcards
extraction
combines two immiscible liquids, one of which easily dissolves the compound of interest.
Polar (water) layer is called the
aqueous phase and dissolves compounds with hydrogen bonding or polarity.
Organic phase
nonpolar layer and dissolves nonpolar compounds.
Extraction is carried out in a
separatory funnel. One phase is collected and the solvent is then evaporated.
acid-base properties can be used to
can be used to increase solubility .
wash
is the reverse of extraction, in which small amounts of solute that dissolves impurities is run over the compound of interest.
Filtration
isolates a solid (residue) from a liquid (filtrate).
gravity filtration
is used when the product of interest is in the filtrate. Hot solvent is used to maintain solubility.
Vacuum filtration
is used when the product of interest is the solid. A vacuum is used when the product of interest is the solid. A vacuum is connected out the flask to pull the solvent through more quickly.
Recrystallization
the product is dissolved in a minimum amount of hot solvent. If the impurities are more soluble, the crystals will reform while the flask cools, excluding the impurities.
Distillation
separates liquids according to differences in their boiling points; the liquid with the lowest boiling point vaporizes first and is collected as distillate.
Simple distillation
can be used if the boiling points are under 150 C and are at least 25 C apart.
Vacuum distillation
should be used if the boiling points are over 150 C to prevent degradation of the product.
Fractional distillation
should be used if the boiling points are less than 25 C apart because it allows more refined separation of liquids by boiling points.
Chromatography
use two phases to separate compounds base on physical or chemical properties.