12.1 Solubility-Base Methods Flashcards
“like dissolves like” meaning
polar substances will associate with other polar substances
nonpolar substances will associate with other nonpolar substances
extraction
the transfer of a dissolved compound (the desired product) from a starting solvent into a solvent in which the product is more soluble
based on the concept “like dissolves like”
leaves most impurities behind in the first/original solvent
“immiscible” meaning
that the two solvents form two layers that do not mix (ex. water and oil)
aqueous phase/layer
consists of polar water
organic phase/layer
the nonpolar phase
what equipment is used to separate the aqueous and organic phases of a separated mixture?
separatory funnel
which layer will be on top/bottom once separated?
while it is more common for the aqueous layer to be on top, the opposite can occur as it depends on their relative densities
the MORE DENSE layer will be on the bottom, the LESS DENSE layer will be on top
effective extractions involve ______ rather than ______
effective extractions involve multiple extraction with fresh water rather than a single extraction with a larger volume of water
how is the product obtained once it has been isolated in solvent
the solvent is evaporated, usually by using a rotary evaporator
what device is used to evaporate the solvent off of the product?
rotary evaporator (rotovap)
washing
the reverse of extraction; removes unwanted impurities into a second solvent
the desired compound stays in its current layer
extraction vs washing
extraction pulls the desired product into a new phase, leaving impurities in the original solvent
washing pulls impurities into a new phase and leaves the desired product in the original solvent
filtration
a process used to separate solids from liquids using a filter (ex. paper) that allows the fluid to pass through but not the solid
what is the solid phase of filtration called?
the residue
what is the liquid phase of filtration called?
the filtrate
gravity filtration
the solvents own weight puts it through the filter
more commonly used when the product of interest is in the filtrate
hot solvent is generally used to keep the product dissolved in liquid
vacuum filtration
the solvent is forced through the filter by a vacuum connected to the flask
more often used when the solid is the desired product
recrystallization
a method for further purifying crystals in solution
first we dissolve our product in a minimum amount of hot solvent and let it recrystallized as it cools
(ideally the impurities remain in the solvent and only the product crystallizes are room temperature)
the crystal is then isolated via vacuum filtration
what type of solvent should be closed for recrystallization? why?
the product is readily soluble at high temperatures but insoluble at room temperature
(so when the solution cools, only the desired product will recrystallize out of solution, excluding impurities)
