(P) Paper Chromatography

• Chromatography is used for separating different dyes in an ink
• In real life, chomatography is useful for identifying unknown substances such as in forensic science.
• 1. Draw a line near the bottom of a sheet of filter paper (use a pencil - pencil marks are insoluble and won't dissolve in the solvent)
• 2. Add a spot of the ink to the line and place the sheet in a beaker of solvent e.g water
• 3. The solvent used depends on what's being tested. Some compounds dissolve well in water, but sometimes other solvents are needed e.g ethanol
• 4. Make sure the ink isn't touching the solvent - you don't want it to dissolve into it
• 5. (Optional) - Place a lid on top of the container to stop the solvent from 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 so the dyes will separate out. (Each dye will form a spot in a different place - 1 spot per dye in the ink)
• 8. If any of the dyes in the ink are insoluble in the solvent used, they'll stay on the baseline
• 9. When the solvent has nearly reached the top of the paper, take the paper out of the beaker and leave it to dry
• 10. The end result is a pattern of spots called a chromatogram