Required Practical 6:Chromatography

• What is the purpose of paper chromatography?

  To identify substances
• Why is it essential to learn the details of paper chromatography?

  It is a required practical
• What should you do before continuing with the chromatography video?

  Watch the previous video on atomic structure
• What is the sample of food coloring referred to in the experiment?

  U for unknown
• How many known food colorings are used in the experiment?

  Four
• What is the first step in carrying out paper chromatography?

  Draw a horizontal pencil line
• How far from the bottom should the pencil line be drawn on the chromatography paper?

  Around 2 cm
• What should be marked on the chromatography paper after drawing the pencil line?

  Five pencil spots at equal spaces
• Why is it important to keep the spots small on the chromatography paper?

  To prevent colors from spreading into each other
• What is used as the solvent in this chromatography experiment?

  Water
• How deep should the water be in the beaker?

  1 cm
• What must be ensured about the pencil line when lowering the paper into the water?

  It must be above the water surface
• Why should the sides of the paper not touch the beaker walls?

  It interferes with water movement
• What is done to reduce evaporation of the solvent during the experiment?

  Put a lid on the beaker
• When should the paper be removed from the beaker?

  When the water has traveled 3/4 up
• What should be marked on the paper after removing it from the beaker?

  The point where the water reached
• What does it indicate if the unknown color separates into three spots?

  It is a mixture of three colors
• How can the identity of the unknown color be determined?

  By comparing spots with known colors
• What is the purpose of calculating RF values?

  To identify the chemicals in the colors
• How is the RF value calculated?

  Distance moved by chemical / distance moved by solvent
• What is the RF value for color A if the distance is 14 mm and the solvent distance is 70 mm?

  $0.2$
• Do RF values have units?

  No, they do not have units
• What should be done if multiple chemicals have the same RF value?

  Repeat the experiment with a different solvent
• What if a chemical has never been analyzed before?

  Further analysis is needed to identify it
• Where can students find questions on this required practical?

  In the vision workbook
• What is the role of the capillary tube in the chromatography experiment?

  To apply small spots of color
• Why is it important to measure distances accurately in chromatography?

  To ensure correct RF value calculations
• What does it mean if the unknown color contains multiple spots?

  It indicates a mixture of chemicals
• How can databases assist in identifying chemicals?

  By providing known RF values for comparison
• What is the significance of further analysis if RF values are not found?

  It helps to identify unknown chemicals