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Chemistry - Separation Techniques - Coggle Diagram
Chemistry - Separation Techniques
Filtration
used to separate an INSOLUBLE solid from a liquid
e.g. sand from water
if a solid in insoluble, it won’t dissolve in a liquid
filter paper folded into cone shape, solid is left over in paper
Evaporation
used to separate SOLUBLE solid from a liquid
e.g. salt from water
separate soluble solids from solutions
Method
pour solution into evaporating dish
slowly heat solution (with bunsen burner)
solvent will evaporate, solution will become more concentrated
crystals start to form
keep heating until left with dry crystals
Chromatography
Method
draw line near bottom of a sheet of filter paper (pencil - insoluble)
add spot/s of ink to line
place sheet in a beaker of solvent (e.g. water) - depends on what’s being tested
make sure ink isn’t touching solvent
place lid on container - prevent evaporation
solvent seeps up paper
when solvent almost at top of paper - take it out and dry
end result - chromatogram
each spot of chromatography is a different dye in ink
they separate because each one moves up paper at different rate
Crystallisation
use if salt decomposes
Method
pour solution into evaporating dish
gently heat
when some of solvent has evaporated OR when crystals start to form
remove dish from heat
leave to cool
should form crystals as it becomes insoluble
filter crystals out of solution
leave in warm place to dry
Distillation
used to separate a liquid from a solution
Method
solution is heated
part of solution that has the lowest boiling point evaporates first
vapour is cooled, condenses, and collected
rest of solution left behind in flask
only use it to separate things with very different boiling points
Fractional Distillation
mixture of liquids
Methods
put mixture in flask, stick a fractionating column on top
heat it
different liquids - different boiling points (evaporate at different temperatures)
liquid with lowest boiling point evaporates first
liquids with higher boiling points may start to evaporate
column is cooler at top, condense and run back down
when first liquid has been collected, raise temperature until next reaches top