chromatography

• pure compound


  produces a single spot in all solvents
• compounds in a mixture may seperate into different spots depending on the solvent
• pen ink could dissolve in the solvent and move up the paper whereas pencil marks are insoluble and wont dissolve in the solvent
• Mobile Phase


  The material that moves, carrying the components of the mixture through the stationary phase.
• Stationary Phase


  The material that remains still, separating the components of the mixture.
• Solvent


  A substance that dissolves the mixture, allowing it to be separated.
• How to do Paper Chromatography

  1. Draw a line near the bottom of a sheet of filter paper

  2. Add a spot of the ink to the line and place the sheet in a beaker of solvent

  3. The solvent used depends on what's being tested

  4. Make sure the ink isn't touching the solvent

  5. Place a lid on top of the container to stop the solvent evaporating

  6. The solvent seeps up the paper, carrying the ink with it

  7. Each different dye in the ink will move up the paper at a different rate

  8. If any of the dyes in the ink are insoluble, they'll stay on the baseline

  9. When the solvent has nearly reached the top of the paper, take the paper out and leave it to dry

  10. The end result is a pattern of spots called a chromatogram
• Chromotography is used to test athletes urine samples for perfomance enhancing drugs
• The point the solvent has reached as it moves up the paper is the solvent front