Further syntheis and analysis

• What is chromatography used for?

  To separate and identify component molecules
• What are the two phases used in chromatography?

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

  It allows molecules to move over the stationary phase
• What forms can the mobile phase take?

  Liquid or gas
• How do more soluble products behave in chromatography?

  They move further with the mobile phase
• What is the stationary phase in chromatography?

  A substance with affinity to molecules in the mixture
• What happens to molecules with greater affinity to the stationary phase?

  They move shorter distances with the mobile phase
• What does the Rf value represent?

  A unique value for each component molecule
• How is the Rf value calculated?

  By comparing distances moved by mobile phase and molecule
• What are the four main types of chromatography?

  1. Thin-Layer Chromatography
  2. Column Chromatography
  3. Gas Chromatography
  4. GC-MS (Gas Chromatography-Mass Spectrometry)
• What is the method used in Thin-Layer Chromatography?

  A metal plate coated with silica is used

  
• What is NMR spectroscopy used for?

  Determining the structure of a molecule
• How does NMR spectroscopy analyze bond environments?

  By analyzing the energy absorbed by bonds
• How is the solvent used in Thin-Layer Chromatography?

  It moves up the plate

  
• What does each peak in an NMR spectrum represent?

  Different bond environments in a molecule
• What is done to the plate after Thin-Layer Chromatography?

  It is dried in a fume cupboard
• How can chemical traces be viewed in Thin-Layer Chromatography?

  Using a UV lamp or developing agent
• What standard molecule is used in NMR spectroscopy?

  Tetramethylsilane (TMS)

  
• What is the stationary phase in Column Chromatography?

  A solid, powdered substance packed in a vertical column
• Why is TMS used as a standard in NMR?

  It has identical carbon and hydrogen environments
• How does the mobile phase behave in Column Chromatography?

  A solvent containing the mixture moves down the column
• What does the varying affinities of molecules in Column Chromatography allow?

  Molecules to drain out at different times
• What is retention time in Column Chromatography?

  The time taken for molecules to drain out
• At what value does TMS appear on the NMR spectrum?

  ∂=0 ppm
• What does C¹³ NMR analyze?

  The different carbon environments in a molecule
• What is the stationary phase in Gas Chromatography?

  A solid, powdered substance packed in a thin tube
• What is used as the mobile phase in Gas Chromatography?

  A high pressure gas
• What type of mixtures is Gas Chromatography used to separate?

  Mixtures of volatile liquids
• How do carbon environments near oxygen behave in NMR?

  They have shifted ∂ values to the right
• How does the analysis machine in Gas Chromatography work?

  It records a retention time for each component
• What does GC-MS combine?

  Gas chromatography and mass spectrometry

  
• Why might a molecule with symmetry show fewer peaks in NMR?

  It has identical environments for some carbons
• What is the advantage of using GC-MS?

  It produces faster and more accurate results
• How many carbon atoms does 1,2-cyclohexanediol contain?

  Six carbon atoms
• What happens to molecules in GC-MS after separation?

  They are fed into a mass spectrometer for identification
• How many peaks does the NMR spectrum of 1,2-cyclohexanediol show?

  Three peaks

  
• What are the key features of GC-MS?

  • Combines gas chromatography and mass spectrometry
  • Allows advanced molecule analysis
  • Faster analytical process
  • Produces more accurate results

  
• Where can C¹³ NMR ∂ shift values be found?

  On the AQA Chemistry Data Sheet
• What does H¹ NMR analyze?

  The different hydrogen environments in a molecule
• Why must samples for H¹ NMR be dissolved in a non-hydrogen-containing solvent?

  To avoid producing additional ∂ peaks