salt16
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


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