Paper chromatography

• What technique is used to separate substances in a mixture?

  Chromatography
• What is the purpose of paper chromatography?

  To separate and identify substances in a mixture
• What is the first step in paper chromatography?

  Draw a baseline with a pencil
• Why is the solvent level kept shallow in chromatography?

  To prevent submerging the pencil line
• What happens to the different dyes during chromatography?

  They travel at different rates up the paper
• What is the pattern of spots left after chromatography called?

  Chromatogram
• What are the mobile and stationary phases in chromatography?

  Mobile phase is the solvent; stationary phase is the paper
• How do the properties of substances affect their movement in chromatography?

  Solubility determines how fast they move
• What does a single spot on a chromatogram indicate?

  The sample is a pure substance
• What is the formula for calculating the rf value?

  rf = distance travelled by substance / distance travelled by solvent
• If a substance travels 6 cm and the solvent travels 10 cm, what is the rf value?

  $0.6$
• How does changing the solvent or paper affect the chromatogram?

  It may change the appearance and rf values
• Why must chemists consider the solvent and paper type when looking up rf values?

  Different conditions affect the rf values
• What are the steps involved in performing paper chromatography?

  1. Draw a baseline on filter paper.
  2. Add ink sample to the baseline.
  3. Prepare a shallow solvent in a beaker.
  4. Place the paper in the solvent without submerging the ink.
  5. Cover the beaker to prevent evaporation.
  6. Wait for the solvent to rise and separate the dyes.
  7. Remove the paper and let it dry to observe the chromatogram.
• What factors influence the movement of substances in chromatography?

  • Solubility in the solvent
  • Attraction to the stationary phase (paper)
  • Time left in the experiment