chapter 12: separations and purifications

usually a polar solid

stationary phase or adsorbent

runs through the stationary phase and is usually a liquid or gas

mobile phase

smaller rf

higher affinity for the stationary phase

paper chromatography stationary phase

polar material, such as silica, alumina, or paper

paper chromatography mobile phase

nonpolar solvent

utilizes polarity, size, or affinity to separate compounds based on their physical or chemical properties

column chromatography

column chromatography stationary phase

a column containing cilica or aluminum beads

column chromatography mobile phase

nonpolar solvent

beads are coated with charged substances to bind compounds with opposite charge

ion-exchange chromatography

beads have small pores which trap smaller compounds and allow larger compounds to travel through faster

size-exclusion chromatography

separates vaporizable compounds according to how well they adhere to the adsorbent in the column

gas chromatography

gas chromatography stationary phase

a coil of crushed metal or a polymer

gas chromatography mobile phase

nonreactive gas

ionizes and fragments molecules and passes these fragments through a magnetic field to determine molecular weight or structure

mass spectrometry

combines 2 immiscible liquids, one of which easily dissolves the compound of interest

extraction

polar layer that dissolves compounds with hydrogen bonding or polarity

aqueous phase

nonpolar layer that dissolves nonpolar compounds

organic phase

reverse of extraction, in which a small amount of solvent that dissolves impurities is run over the compound of interest

wash

isolates a solid from a liquid

filtration

used when the product of interest is in the filtrate

gravity filtration

used when the product of interest is solid

vacuum filtration

the product is dissolved in a minimum amount of hot solvent

recrystallization

separates liquids according to differences in their boiling points

distillation

can be used if the boiling points are under 150 degrees celsius and are at least 25 degrees apart

simple distillation

should be used if the boiling points are over 150 degrees celsius to prevent degradation of the product

vacuum distillation

should be used if the boiling points are less than 25 degrees apart because it allows more refined separation of liquids by boiling point

fractional distillation