Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
-----------------
ammonium persulfate : (NH4)2S2O8
sodium hydroxide : NaOH
acetone : CH3 CO CH3
sodium thiocyanate : NaSCN
nickel sulfate : NiSO4 . 6H2O
Class:
------
elem=Ni
coordination
precipitation
redox
Summary:
--------
Nickel does not appear to build coordination complexes with thiocyanate,
not even if acetone is added (in contrast to cobalt).
Ni(OH)2 is oxidized to a dark compound by persulfate, even in the presence
of a reducing agent like acetone.
Description:
------------
Add a solution of sodium thiocyanate to a solution of nickel sulfate: No
visible reaction.
Add a fairly large amount of acetone: No changes, the acetone mixes with the
aqueous solution.
Add a solution of NaOH: Formation of a pale green precipitate.
Add a solution of ammonium persulfate: The precipitate turns dark brown. The
smell of NH3 can be detected through the smell of acetone. The latter is due
to the presence of NaOH, which causes the ammonium ions to be decomposed to
ammonia.