condennnsa - 10-4-2017 at 05:50
So I kept most of my chemicals after moving untouched for about 5 years now, and discovered my iron sulfate turned to this gunk:
The FeSO4 was prepared from battery electrolyte sulfuric acid and nails.
Honestly, I didn't know that it is not stable in air
from wikipedia: Upon exposure to air, it oxidizes to form a corrosive brown-yellow coating of "basic ferric sulfate", which is an adduct of iron(III)
oxide and iron(III) sulfate:
12 FeSO4 + 3 O2 → 4 Fe2(SO4)3 + 2 Fe2O3
my question is what should I do to turn it back to pure ferrous sulfate?
elementcollector1 - 10-4-2017 at 06:35
Recrystallize in a slightly acid solution, maybe?
Texium - 10-4-2017 at 07:26
Dissolve it in water (it will be cloudy) and then add sulfuric acid dropwise until the solution goes clear. Add a generous excess iron to the
solution, and allow the iron to react until the yellow color has disappeared. Stir it well to make sure all of the solution is reduced. Then just
filter off the excess iron and recrystallize it. Make sure that it's completely dry when you store it, as water will accelerate the oxidation a lot.
Store it in an airtight container, densely packed together to try and exclude as much air as possible.