More Details in Separation (Hehehe...)

Helloo!! We are back.

We are going to tell you more about different separation techniques.

Hand Separation:

• Used usually for mechanical mixture or heterogeneous mixtures
• separation by a hand, magnet or a sieve
• Evaporation which is solid dissolved in liquid solution or boil away the liquid and solid remains

Filtration:

• deals with solids(not dissolved) and liquids
• passing a mixture that contains solid particles through a porous filter
• the liquid pass through the filter and residue is left on the filter
• separation by using filter paper

Crystallization:

• solids in liquids
• Precipitation: conversion of a solute to solid form by chemical or physical change
• after, solids are separated by filteration or floatation
• saturated solution of a desired solid evaporate or cool - solid come out as crystals

Gravitiy Separation:

• solids based on gravity
• centrifuge whirls the test tube around at high speed forcing the denser materials to the bottom
• Works best for small volumes

Solvent Extraction:

• a component moves into a solvent shaken with the mixture
• works best with solvents that dissolve only one component
• For mechanical mixtures: use liquid to dissolve one solid but not the other so that the desired solid is left behind or dissolved
• Solution: solvent is insoluble with solvent already present

Distillation:

• Heating a mixture creates vapour
• collecting and condensing vollatillized components
• liquid with lowest boiling point boils first
• vapour ascents to distillation flask and enters condenser
• gas cools and condenses > back to liquid and distillates as a purified liquid

Chromatography:

•  Flow mixture over a material and different components goes in different speeds and stops
• mobile phase sweeps the sample over a stationary phase
• can separate complex mixtures
• very small sample sizes; analysis is highly accurate and precise
• separated components can be collected individually

Paper Chromatography:

•  Stationary Phase: liquid soaked into sheet of paper
• Mobile Phase: liquid solvent some components spend more time in the stationary phase than others after drying; spots appear on the paper

Thin layer Chromatography (TLC):

• Stationary Phase: thin layer of absorbent (Al203 or SiO3) coating a sheet of plastic or glass
• some components bond to the absorbent strongly; others more weakly
• appear as spots

Written by JK (Oct 18, 2010)