Paper chromatography

• What is one method of separating substances in a mixture?

  Chromatography
• How can chromatography be used with ink?


  It can separate different dyes in the ink
• What are the steps to perform paper chromatography?


  1. Draw a line near the bottom of filter paper with a pencil.
  2. Add a spot of ink to the line.
  3. Place the sheet in a beaker of solvent (e.g., water).
  4. Ensure the ink doesn't touch the solvent.
  5. Cover the container to prevent evaporation.
  6. Allow the solvent to seep up the paper.
  7. Observe the separation of dyes.
  8. Remove the paper when the solvent nears the top.
  9. Let the paper dry to form a chromatogram.
• Why should you use a pencil instead of a pen to draw the line on the filter paper?

  Pencil marks are insoluble and won't dissolve in the solvent
• What should you do if the ink touches the solvent during chromatography?


  You should ensure the ink doesn't touch the solvent
• What happens to the solvent during paper chromatography?


  The solvent seeps up the paper, carrying the ink with it
• How do different dyes behave during chromatography?


  Each dye moves up the paper at a different rate
• What is formed at the end of the chromatography process?


  A pattern of spots called a chromatogram
• What happens to insoluble dyes during chromatography?


  They stay on the baseline
• What are some real-life applications of chromatography?


  • Testing athletes' urine samples for performance-enhancing drugs
  • Analyzing unknown substances at crime scenes
• What is the purpose of placing a lid on the container during chromatography?

  To stop the solvent from evaporating
• Why is chromatography considered useful in real life?


  It helps in testing substances for various applications
• What is the solvent commonly used in paper chromatography?


  Water
• What should you do when the solvent has nearly reached the top of the paper?


  Take the paper out of the beaker and leave it to dry
• What is the main reason for using different solvents in chromatography?


  Some compounds dissolve well in different solvents
• What is the technique used to separate different substances in a mixture?

  Paper chromatography
• What is the purpose of using a base line in paper chromatography?


  To mark where the sample is applied on the paper
• How far should the base line be from the bottom of the chromatography paper?


  2 cm away
• Why is it important to stop the solvent from evaporating during chromatography?


  To ensure accurate separation of substances
• What type of solvent is typically used in paper chromatography?


  Water or ethanol
• What happens to the solvent in paper chromatography?


  The solvent seeps up the paper
• How do different dyes behave in the solvent during chromatography?


  Different dyes dissolve and move up at different rates
• What should not be submerged in the solvent during chromatography?

  The baseline
• What is a chromatogram?


  A visual representation of the separation of substances
• What are the two phases involved in chromatography?


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


  The phase where molecules can move (liquid/gas)
• What is the stationary phase in chromatography?


  The phase where molecules can't move (solid/liquid)
• How is the Rf value calculated in chromatography?


  Rf value = distance travelled by substance / distance travelled by solvent
• What does a pure substance show on a chromatogram?


  A single spot
• How does the Rf value of a pure substance compare to that of a mixture?


  The Rf value is specific for a pure substance
• What does the Rf value depend on?


  The properties of that substance
• What happens to the solvent front when the chromatography process is complete?


  It should not reach the top of the paper
• What is indicated by the presence of different spots on a chromatogram?


  Each spot represents a different substance