Separations and Purifications Flashcards
What type of separation uses two immiscible solvents?
Extraction
What are the two layers of an extraction?
Aqueous and organic
Is the organic phase polar or nonpolar?
Nonpolar
Will the denser layer be at the top or bottom of an extraction?
Bottom
What is the opposite of an extraction?
Wash
What is filtration good for separating?
Solid and liquid
What is contained in the filtrate?
Liquid
What is contained in the residue?
Solid
What layers do the liquid and solid separate into during filtration?
Liquid becomes the filtrate and solid becomes the residue
What is recrystallization?
Purifying crystals using hot solution
What does distillation rely on and what is it good for separating?
Relies on differences in boiling point and good for separating two liquids
What is the distillate?
The condensed product of distillation, the liquid with the lower boiling point, which boils first
When is a vacuum distillation appropriate?
BP>150C
When is a simple distillation appropriate?
BP<150 and BP more than 25C apart?
When is a fractional distillation appropriate?
BPs very close together
What makes fractional distillation different?
Column contains inert objects up the distillation columb
What is the best way to identify unknown compounds?
Chromatography
What is the stationary phase in thin layer chromatography and what is its polarity?
Silica or alumina
Polar
What is the stationary phase in paper chromatography and what is its polarity?
Paper (cellulose)
Polar
With a polar stationary phase, what moves farthest?
Nonpolar substances
What is reverse phase chromatography?
Stationary phase is nonpolar
What is Rf
Distance the spot moved divided by distance the solvent front moved
What is column chromatography?
Column filled with aluminum or silica beads that uses gravity to separate compounds down the column
What happens in flash chromatography?
Gas pressure is used to force solvent down the column
What is ion-exchange chromatography best used for?
Uses charged beads that retain compounds with the opposite charge
What is size-exclusion chromatography best used for?
Beads have tiny holes in them that slow down smaller molecules and allow larger ones to move quickly through the column
What is affinity chromatography best used for?
Column is created with receptor or antibody used to bind a protein of interest
What is gas chromatography?
Eluent is a gas (usually nitrogen or helium)
