Description of experiment
Below follows a plain text transcript of the selected experiment.
Needed compounds:
-----------------
sodium thiocyanate : NaSCN
nitric acid : HNO3
hydrochloric acid : HCl
ferric oxide : Fe2O3
Class:
------
elem=Fe
coordination
Summary:
--------
Ferric oxide (Fe2O3, dark red/brown) dissolves in hydrochloric acid and
nitric acid, but with extreme difficulty and in very small quantities.
Description:
------------
Sequence 1:
-----------
Add some Fe2O3 to HCl (appr. 30% by weight): The solid does not dissolve.
Heat the liquid for a while: A minute part of the solid has dissolved. After
standing for a while (when the solid sinks to the bottom again), the liquid
is very light yellow.
Add a dilute solution of NaSCN: The liquid becomes deep blood red.
Sequence 2:
------------
Add some Fe2O3 to HNO3 (appr. 50% by weight): The solid does not dissolve.
Heat the liquid for a while: A minute part of the solid has dissolved. After
standing for a while (when the solid sinks to the bottom again), the liquid
still looks colorless.
Dilute the acid somethat (to appr. 25%) and again heat for a while: The solid
does not dissolve more easily now. After heating a few minutes and letting
liquid come to rest, it still looks colorless.
Add a dilute solution of NaSCN: The liquid becomes deep blood red, but this
color fades again after a few seconds. Above the liquid, a white fume is
produced and some nitrous vapours (brown NO2) can be observed. Apparently
the thiocyanate is oxidized by the nitric acid.