A scheme for the pre investigation of a pure substance.



More can be found in module 05, chapter 3 about properties of pure substances

  1. General:
    1. Write the color of the substance (see also table XVII)
    2. Execute the 'flame coloring (tablé XIIX)
    3. Note the behaviour at heating (some substances decompose at heating, and then melting point/boiling points cannot be determined)

  2. Solids (s):
    1. polishing the substance with metalic shine; the substance appears to be conducting electricity; that this must be a metal with a metalic lattice.
      Exaomples: red: copper, yellow: brass or gold, brownish red: bronze, strongly affected / rusty: iron etc.
    2. the substance has a low melting point and is not conducting electricity:
      Must be a molecular lattice
      • investigate the solubility of the substance in different (non) polar solvents.
      • then investigate with...
      • an indicator (if aq)
      • spectrometry
      • chromatography
    3. the substance has a high melting point and does not conduct:
      Must be an ionic lattice.
      • Mix the substance with water and find:
        • the solubility
        • the conductibility
        • reaction at an indicator
        • do spectrometry (including the flame reaction)
        • do chromatography

  3. The substance is a liquid.
    Think here of a number of options:
    • polar/no polar molecules
    • small / big / long shaped molecules
    • probably no lattices
    • unsaturated carbon chains
    possible investigation:
    1. mixing with (non) polar liquids
    2. viscosity
    3. boiling point
    4. spectrometry
    5. (gas)chromatography

  4. You must investigate a gas (g).
    The substance will be built up of small, light molecules with little dipole character.
    Options for investigation:
    1. solubility in liquids
    2. gas chromatography