Seperation Technique Flashcards
Filtration?
It is used to separate suspended particles from a liquid
Precautions of filtration?
Filter funnel should be filled only uptick two thirds
Glass rod to direct suspension
Stem of funnel should touch the walls of the beaker
Decantation?
Mixture allowed to stand. Sediments gather at the bottom
The liquid in decantation?
Supernatant
Centrifuging?
Decantation done in machine. Sediment is more solid at the bottom
How to separate dissolved solids from liquids? (3)
Boiling/ evaporation
Crystallisation
Chromatography
Evaporation?
Used to concentrate dilute solutions without heating
How to gain back solvent from evaporation?
Condensation or distillation
Precautions of evaporation to dryness?
Spitting
Not suitable for salts with water of crystallisation
What physical change occurs due to loss of water of crystallisation?
Change of colour
Advantage of evaporation?
Solute can be obtained in dry form
Disadvantage of evaporation?
Solvent is lost
Impurities are also left behind
Crystallisation?
Separate solute in form of crystals from its aqueous or non aqueous form
Crystallisation is useful for?
Salts that are heat liable
How is crystallisation done?
Cooling a hot liquid over a water bath and drops of solution are taken out to check if crystals are forming or not.
After crystals are formed what is done?
It is washed with distilled water and then dried with filter paper
Advantages of crystallisation ?
No impurities
Disadvantage of crystallisation?
Not all solute will form crystals
How to improve water of crystallisation? (2)
Inner walls or evaporating dish to be scrapped
Seeding
Chromatography?
Separate coloured components from a single mixture
Solvent front?
The total distance travelled by a mixture
Solute front?
Distance travelled by one component of the mixture
How to calculate from value?
Solute front/ solvent front
How to separate spots?
Cut them and dissolve in solvent . Solution to be then evaporated
