salt18
Rebuilding of the coloured iron(III) salt at the air
Hydrochloric acid is corrosive! Use goggles, work in a trash, ask an adult to join you.

In the previous experiment the colour of iron(III) thiocyanate Fe(SCN)3 disappeared because the iron(III) ions were reduced by hydrogen from iron and acid.
* Remove the steel wool from the bottle with the colourless solution, add one more drop of ammonium thiocaynate indicator.
Observation Photo 1 + 2: After some time at the air the redbrown colour appears again starting from the surface. The last micro fibres of steel wool and the bubbles disappear
Explanation: The iron(II) ions are oxidised by the oxygen of the air. The iron(III) ions obtained by this reaction are indicated as the redbrown salt iron(III) thiocyanate Fe(SCN)3


back............ go on...................first published: 18.10.2001...................... ......last modification: 25.03.2007