A scheme for the pre investigation of a pure substance.
More can be found in module 05, chapter 3
about properties of pure substances
- Write the color of the substance (see also table XVII)
- Execute the 'flame coloring (tablé XIIX)
- Note the behaviour at heating (some substances decompose at heating, and then melting point/boiling points cannot be determined)
- Solids (s):
- 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.
- 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)
- 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
- 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
- mixing with (non) polar liquids
- boiling point
- You must investigate a gas (g).
The substance will be built up of small, light molecules with little dipole character.
Options for investigation:
- solubility in liquids
- gas chromatography