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 used in chromatography?

  Chromatography paper
• What is the stationary phase in paper chromatography?

  The paper that does not move
• What is the mobile phase in paper chromatography?

  The solvent that moves up the paper
• What does a single spot indicate in chromatography?

  The substance is a pure compound
• How does solubility affect the distance traveled in chromatography?

  More soluble substances travel further
• Why do we draw the starting line in pencil?

  To prevent the line from moving with 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
• What is the RF value calculated in the example?

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

  They may need further analysis for identification
• What happens if a substance has never been analyzed before?

  There will be no RF value in the database
• What are the steps in a paper chromatography experiment?

  1. Draw a pencil line on chromatography paper.
  2. Place dots of colors on the line.
  3. Immerse the paper in a solvent.
  4. Allow the solvent to move up the paper.
  5. Measure distances moved by substances 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 separation.
• What are the benefits of using paper chromatography?

  • Identifies unknown substances.
  • Separates mixtures effectively.
  • Visualizes different components.