C18.5 Paper Chromatography (Part 1, Coloured)

• The solvent is the liquid that moves up the paper
• A spot test is used to identify an unknown compound by comparing its reaction with known compounds
• Paper chromatography separates mixtures into their individual components based on differences in polarity, which affects how they interact with the stationary phase and mobile phase.
• A spot on the chromatogram represents one compound
• Rf value = distance traveled / total distance traveled
• In paper chromatography, the mixture is applied as a small dot at the bottom of the paper strip, then placed in a container containing the solvent. The solvent rises through the paper, carrying the different substances along with it.
• As the solvent travels up the paper, the more polar substances are attracted to the water molecules in the paper fibers, while less polar substances move further up the paper due to their attraction to the nonpolar cellulose fibers.
• Spots are separated from each other because different substances move at different rates along the paper
• paper chromatography


  • used to separate 1 substance from a mixture
  • to check whether a substance is pure
  • to identify substances in a mixture
• paper chromatography method:

  1. a line is drawn on a piece of chromatography paper, using a black pen
  2. the paper is stood in a beaker with ethanol. the ink line is above the level of ethanol
  3. ethanol rises up the paper, dissolving the ink. bands of different colours appear.
• to separate substances in paper chromatography, a solvent that can dissolve all substances is needed. ethanol is a good choice
• ethanol moves up paper by capillary action. when it reaches the ink line, ethanol dissolves the substances in the ink and they travel with it. each substance travels at a different speed. it depends on their attraction to the ethanol and the paper. the most soluble substance travels the fastest. the result is that substances separate. the paper holding the separated substances will be called the chromatogram.
• chromatography can be used to identify which substance is present in a mixture