Chromotography

• What is chromatography used for?

  To separate and identify the substances in a mixture
• What are the two phases in chromatography?

  The mobile phase and the stationary phase
• What is the mobile phase in chromatography?

  A liquid or a gas where molecules can move
• What is the stationary phase in chromatography?

  A solid or a thick liquid where molecules can't move
• How do components in a mixture separate during chromatography?

  They separate as the mobile phase moves over the stationary phase
• What determines how fast a chemical moves through the stationary phase?

  How it distributes itself between the two phases
• What is the mobile phase in thin-layer chromatography (TLC)?

  A solvent, such as ethanol
• What is the setup method for thin-layer chromatography (TLC)?

  1. Draw a line near the bottom of the plate with a pencil.
  2. Put a spot of the mixture on the line.
  3. Dip the bottom of the plate into the solvent.
  4. Cover the beaker with a watch glass.
  5. Allow the solvent to move up the plate.
  6. Remove the plate before the solvent reaches the top and mark the solvent front.
• What happens to the chemicals in the mixture during TLC?

  They dissolve in the solvent and move up the plate
• What factors affect how long molecules spend in each phase during chromatography?

  How soluble they are in the solvent and how attracted they are to the stationary phase
• How do molecules with higher solubility behave in chromatography?

  They spend more time in the mobile phase and move further up the plate
• How is paper chromatography similar to thin-layer chromatography (TLC)?

  • Both use a solvent as the mobile phase.
  • Both separate components of a mixture.
  • The stationary phase in paper chromatography is chromatography paper.
• What is the stationary phase in paper chromatography?

  A sheet of chromatography paper, often filter paper
• What is the mobile phase in paper chromatography?

  A solvent such as ethanol
• What is chromatography considered as?

  An analytical method
• Why is it important to use a pencil for marking in chromatography?

  Because pencil marks are insoluble and won't move with the solvent
• What is the purpose of the watch glass in the chromatography setup?

  To stop any solvent from evaporating away
• What should you do after the solvent has moved up the plate?

  Remove the plate before the solvent reaches the top
• What is the significance of marking the solvent front?

  It indicates how far the solvent has moved