Filtration, crystallisation & chromatography

• What does filtration do?

  It separates a solvent from an insoluble solute. For example, sand from a mixture of sand and water.
• How does filtration work?

  The mixture is poured into the conical flask. The solvent goes through the filter paper and into the flask as the solute collects in the filter paper.
• What is the equipment needed for this experiment and provide a diagram.

  -Clamp and stand

  -filter paper

  -funnel

  -conical flask

  
• What does crystallisation do?

  It separates a dissolved solute from a solvent. For example, salt and ammonium chloride.
• How does crystallisation work?

  The solution starts to boil and the water evaporates leaving cold, hard crystals as the solute.
• What is the equipment needed for this experiment and provide a diagram.

  -gauze.

  -bunsen burner.

  -evaporating basin.

  
• What does chromatography do?

  It separates pure substances from impure substances.
• How does chromatography work?

  On the bottom line of the filter paper, draw a line in pencil across. Place dots of ink from the solute. Place the paper in water just below the pencil line and wait for the colours to separate.
• What are the two phases of chromatography?

  Mobile phase and stationary phase.
• What is the mobile phase?


  The liquid or gas that carries the sample through the chromatography system.
• What is the stationary phase?

  It is where the molecules can't move. This can be a solid.
• What is the equipment needed for this experiment and provide a diagram.

  -Lid.

  -Beaker.

  -Chromatography paper.

  -Dye.

  -Pencil.

  
• How do you calculate the Rf value?

  distance travelled by compound ÷ distance travelled by solvent front.
• How do you reduce risks during filtration?

  Choose filters with appropriate pore sizes and efficiencies to ensure effective filtration.
• How do you reduce risks during crystallisation?

  Adding small quantities of pre-prepared seed crystals.