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Chromatography quiz

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  • What is the main purpose of chromatography?
    Chromatography is used to separate components within a mixture based on their molecular attractions.
  • What are the two phases involved in chromatography?
    The two phases are the stationary phase (usually a silica plate) and the mobile phase (a solvent).
  • What is the stationary phase in chromatography?
    The stationary phase is the part that does not move, typically a silica plate that holds the mixture.
  • What is the mobile phase in chromatography?
    The mobile phase is the moving solvent that travels up the plate by capillary action.
  • How is a mixture applied in chromatography?
    A sample of the mixture is spotted onto the stationary phase, such as a TLC plate.
  • What determines how far a component travels in chromatography?
    The distance a component travels depends on its affinity for the solvent versus the plate.
  • What happens if a component has a greater attraction to the plate than the solvent?
    It will not move very far up the plate, resulting in low movement.
  • What happens if a component has a greater affinity for the solvent than the plate?
    It will move further up the plate with the solvent, showing higher movement.
  • What is capillary action in the context of chromatography?
    Capillary action is the process by which the solvent moves up the plate, carrying the mixture's components.
  • How are the positions of components marked on a TLC plate?
    Positions are marked as starting line, where each component stops, and where the solvent front stops.
  • What is the Retention Factor (Rf value) in chromatography?
    The Rf value is the ratio of the distance traveled by the compound to the distance traveled by the solvent.
  • How do you calculate the Rf value for a compound?
    Divide the distance traveled by the compound by the distance traveled by the solvent.
  • What does an Rf value of 0.50 indicate about a compound's affinity?
    It indicates the compound has a lower affinity for the solvent compared to a compound with a higher Rf value.
  • How can Rf values help identify compounds in a mixture?
    Rf values are compared to known values in a manual to identify the compounds present.
  • What is the typical composition of a solvent used in chromatography as described in the lesson?
    A solvent can be a mixture, such as 50% ethanol (slightly polar) and 50% hexanes (non-polar).