June 21, 2024, 10:44:25 PM
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Topic: FeSO4 vs. Fe2(SO4)3 how to tell the difference?  (Read 2832 times)

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Offline hartalinstalin69

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FeSO4 vs. Fe2(SO4)3 how to tell the difference?
« on: August 04, 2023, 09:41:23 AM »
I just bought a fertilizer labeled FeSO4 .7H2O but it's yellow in color and it's a powder instead of green crystals, I think they either have an old batch of FeSO4 that has oxidized to Fe2(SO4)3 and they are selling it anyway or they are lying for some reason but I'm not sure please did I recognize the scam/mistake correctly? If you would like a photo then email me and I will send it to you? thanks in advance  ???

Offline Borek

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Re: FeSO4 vs. Fe2(SO4)3 how to tell the difference?
« Reply #1 on: August 04, 2023, 01:32:08 PM »
You can attach the photo to the post, just make sure to resize it so that the file is not too large.

Most Fe(II) salts are unstable, so even without seeing the sample it is quite possible you are right.
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Offline Aldebaran

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Re: FeSO4 vs. Fe2(SO4)3 how to tell the difference?
« Reply #2 on: August 05, 2023, 11:12:27 AM »
Jumping to a conclusion...it is possible that what you have is some old stock and now comprises a mixture of Fe3+ basic sulfate, Fe3+ oxides/hydroxides plus the remains of the original Fe2+ sulfate. Atmospheric oxygen is capable of oxidising Fe2+ to Fe3+. The kinetics are affected by pH amongst other things but overall it is a recognised fact that ferrous sulfate exposed to air can form a mixture of various ferrous and ferric compounds.
Assuming the original compound was indeed Fe2+ sulfate the extent to which it has reacted is not possible to tell without chemical analysis. Although the pure Fe3+ ion is a pale lilac colour, in its compounds generally yellow/orange/browns predominate. But colour alone does not give a reliable indication of the extent of the chemical change.
I have no idea of how this might affect its efficacy as a garden treatment.

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