Paper chromatography

• Paper chromatography

  1. Take a piece of filter paper

  2. Draw a line near the bottom (baseline)

  3. Add sample (ink)

  4. Find a beaker and fill with shallow solvent (water or ethanol)

  5. Place filter paper in solvent (but don't submerge baseline and sample)

  6. Wait for solvent to seep up paper
• Chromatogram


  Pattern of spots left on paper after chromatography
• Mobile phase


  Substance (liquid or gas) that the molecules can move in
• Stationary phase


  Substance or material (solid or thick liquid) that the molecules can't move in
• Chemicals spend more time in mobile phase


  They move faster up the paper
• Chemicals spend more time in stationary phase


  They move slower up the paper
• RF value


  Ratio of distance travelled by substance to distance travelled by solvent
• A pure substance with only one chemical won't separate out, just gets a single spot
• Changing mobile or stationary phase changes the RF value for the same substance