When combined iron (III)
and thiocyanate ions form Òblood redÓ complexes. So in this experiment, spectrophotometric methods
will be used to determine the concentration of the iron
(III) cyanato complex, [FeSCN 2+ ].
This however is difficult because the thiocyanate ion, SCN-, can react with the ferric ion, Fe 3+, in acidic solutions to form a series
of thiocyanato-
complexes: Fe(SCN) 2+ ,
Fe(SCN)2+ , Fe(SCN)3, and Fe(SCN)4–.