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 avoid submerging the pencil line
• What do we call the pattern of spots left after chromatography?

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

  Mobile phase is the solvent; stationary phase is the paper
• How do different dyes behave during chromatography?

  They travel at different rates up the paper
• What happens if a chemical is not soluble in the solvent?

  It remains on the baseline
• What determines how fast a chemical moves up the paper?

  Its solubility in the solvent
• What is the formula for calculating the rf value?

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

  $0.6$
• What happens when chromatography is performed with a pure substance?

  It produces a single spot on the chromatogram
• How can changing the solvent or paper affect chromatography results?

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

  Because they affect the chromatogram results
• 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
• 6 marker to seprate ink

  draw a pencil line near bottom edge of chromatography paper

  put small dot of ink on the pencil line

  put small volume of water/ solvent in a beaker

  place chromatography paper in solvent

  dot of ink should be above water level

  support the paper in this position

  put a lid on the beaker

  leave to run

  mark position of solvent front

  remove from beaker and let dry

  determine are values and compare