chromatography

• • chromatography is used to seperate substances in a mixturre and can identify substances
• • chromatography has two phases:
  • mobile phase - where molecules can move, always liquid or gas
  • stationary phase - where molecules cannot move - a solid or thick liquid
• method:

  1. draw pencil line across chromatography paper
  2. add dot of sample ink to pencil line
  3. suspend chromatography paper in beaker of solvent - solvent level must be below pencil line
  4. wait until solvent has moved to top of paper - dot of ink will dissolve in solvent
  5. remove chromatography from beaker of solvent
  6. draw pencil line across paper at point where solvent reached
  7. calculate rF of sample - distance travelled by dye/distance travelled by solvent
  8. compare rF of sample to rF of known dyes