Chromatography

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

  Paper chromatography
• What are the four ways scientists use to separate mixtures?

  Filtration, crystallization, distillation, chromatography
• What does paper chromatography separate substances based on?

  Different solubilities
• How do you start a paper chromatography experiment?

  Draw a pencil line on chromatography paper
• What is the purpose of the solvent in paper chromatography?

  To dissolve substances and carry them up
• What do we call the paper in chromatography?

  The stationary phase
• What do we call the solvent in chromatography?

  The mobile phase
• What does a single spot indicate in chromatography?

  The substance is a pure compound
• What happens to a mixture in chromatography?

  It may separate into different spots
• Why is it important to use pencil for the starting line?

  Pencil does not dissolve in the solvent
• How do you identify an unknown substance using chromatography?

  Measure the distance moved and calculate RF value
• What is the formula to calculate the RF value?

  RF = distance moved by substance / distance moved by solvent
• If a substance moved 44 mm and the solvent moved 75 mm, what is the RF value?

  $0.57$
• What does it mean if multiple substances have the same RF value?

  Further analysis may be needed for identification
• What should you do if the substance has never been analyzed before?

  Conduct further analysis to identify it
• What are the steps in a paper chromatography experiment?

  1. Draw a pencil line on chromatography paper.
  2. Place dots of different colors on the line.
  3. Immerse the paper's bottom in a solvent.
  4. Allow the solvent to move up the paper.
  5. Measure distances moved by the substance and solvent.
  6. Calculate the RF value.
• What are the key facts about pure compounds and mixtures in chromatography?

  • Pure compounds produce a single spot.
  • Mixtures may separate into multiple spots.
  • Solvent choice can affect spot separation.
• What are the roles of the stationary phase and mobile phase in chromatography?

  • Stationary phase: Paper that does not move.
  • Mobile phase: Solvent that moves and carries substances.