Chromatography Flashcards
Stationary phase
Solid substance
Mixture passes over in order to separated
Mobile phase
Liquid or gas
High affinity to stationary phase
Travel slowly
Low affinity to stationary phase
Travel quickly
Highly soluble in mobile phase
Travel quickly with solvent
Low solubility in mobile phase
Travel slowly with solvent
TLC diagram
https://www.chemguide.co.uk/analysis/chromatography/thinlayer.html
Stationary phase in TLC
TLC plate
Thin piece of aluminium/glass coated in silica gel
Mobile phase in TLC
Solvent/eluant
What condition allows spots to become visible in TLC?
UV light/iodine/fluorescent dye
RF equation
RF= distance moved by component/distance moved by solvent front
Advantage of TLC
Faster than paper chromatography
Works on very small samples
Disadvantage of TLC
Similar compounds may have similar Rf values
Cannot be used to separate large quantities
Column chromatography uses
Narrow glass tube with spout and tap- column
Stationary phase in column chromatography
Column packed with powder such as silica
Mobile phase in column chromatography
Solvent/eluant
How is the compound separated in column chromatography
Mixture and solvent run through column
Different components of mixture travel through stationary phase and once reached the bottom, can be collected into separate beakers
Advantage of column chromatography
Larger quantities can be separated
If there is a more polar compound, what would a more polar solvent mean?
Higher solubility to mobile phase
Travels quickly
If there is a more polar compound, what would a more polar stationary phase mean?
Higher affinity to stationary phase
Travels slower
Gas-liquid chromatography used to
separate complex mixtures of volatile compounds
Mobile phase in GC
Carrier gas e.g. nitrogen or helium
Stationary phase in GC
Solid/viscous liquid e.g. alkane, which lines the capillary column
Why can we only explain separation in terms of affinity to the stationary phase?
Mobile phase is not a solvent