NaOH test

• Test method:

  1, add a few drops of sodium hydroxide to your mystery solution

  (this will form an insoluble hydroxide)
• Which hydroxides are a white precipitate? any exceptions?

  Calcium, magnesium, aluminium.

  Aluminium redissolves to form a colourless solution.
• Which irons are tested and what colour precipitate do they form?


  iron (II) - green

  iron (III) - brown
• Which cation produces a green precipitate?

  iron (II)
• what are the six cations tested with sodium hydroxide?

  Calcium, copper, iron (II), iron (III), aluminium, magnesium
• what’s the ionic equation for magnesium reacting with sodium hydroxide?


  Mg2+ + 2OH- -> Mg(OH)2