Sciencemadness Discussion Board

Ferrous sulphate solution smell

wg48temp9 - 16-6-2020 at 02:57

I made a dilute solution of ferrous sulphate to water my acid loving garden plants. I got some of the solution on one of my hands and I noticed a distinct smell similar to the smell when scouring a stainless pan or derusting a steel item.

I am surprised the solution has a smell though I suspect its caused by a reaction with my skin in a similar way that copper when handled generates a smell. The sulphate was technical grade not fertiliser grade.

Has anyone else noticed the smell or has an explanation ?

woelen - 16-6-2020 at 03:06

It's the typical smell of iron. Many metals (and their salts) have that typical smell, when brought in contact with skin. I also know the coppery smell (e.g. from handling money, but also from copper/brass door knobs). A solution of FeSO4 or Fe2(SO4)3 produces an irony smell, when rubbed on skin. A solution of K4Fe(CN)6, however, does not do that. Apparently the iron, bound in the complex, is not capable of giving that smelly compound.

Interesting thing is that apparently, volatile metal compounds are formed in extremely low quantities, but sufficient to be perceived by us as a smell.

j_sum1 - 16-6-2020 at 05:04

Nilered did an interesting video on the "metallic" smell, which does not contain any metal atoms. Let me see if I can find it:

https://www.youtube.com/watch?v=BqLH-nTZEOc

Enjoy.

wg48temp9 - 16-6-2020 at 10:01

I checked the powdered ferrous sulphate bag by putting my nose into the just opened bag perhaps a barely detectable smell that I associate with acid.

I then checked the container I prepared the ferrous solution in no detectable smell when puffing the air it contained in the direction of my nose but it did have the smell faintly around the round mouth. The was some light brown liquid in the bottom of the bottle presumable the result of oxidised ferrous sulphate. I then rubbed some of the solution on my hand and the smell was detected almost immediately. It become stronger in a minute or two but not as strong as when I first noticed the smell with the fresh solution on my hand..

So it is a reaction with my skin, oil or sweat and perhaps only with ferrous ions.

To my nose its not the same smell you get from copper and very different from the smell when scouring an aluminium pan.

Thanks for the link J-sum. I think I have seen that or a similar one in the copper smell thread. Its a pity its so expensive in reagents to make 1-octen-3-one.

Ubya - 16-6-2020 at 11:10

Quote: Originally posted by wg48temp9  
I checked the powdered ferrous sulphate bag by putting my nose into the just opened bag perhaps a barely detectable smell that I associate with acid.

I then checked the container I prepared the ferrous solution in no detectable smell when puffing the air it contained in the direction of my nose but it did have the smell faintly around the round mouth. The was some light brown liquid in the bottom of the bottle presumable the result of oxidised ferrous sulphate. I then rubbed some of the solution on my hand and the smell was detected almost immediately. It become stronger in a minute or two but not as strong as when I first noticed the smell with the fresh solution on my hand..

So it is a reaction with my skin, oil or sweat and perhaps only with ferrous ions.

To my nose its not the same smell you get from copper and very different from the smell when scouring an aluminium pan.

Thanks for the link J-sum. I think I have seen that or a similar one in the copper smell thread. Its a pity its so expensive in reagents to make 1-octen-3-one.



what if you clean your hands with a strong soap solution and the rinse with acetone to remove any oils? if you add the solution to your clean hands immediately after this cleaning, could you still smell the "iron"?

wg48temp9 - 18-6-2020 at 02:19

Quote: Originally posted by Ubya  
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what if you clean your hands with a strong soap solution and the rinse with acetone to remove any oils? if you add the solution to your clean hands immediately after this cleaning, could you still smell the "iron"?


Yes I will try that and I have some rawhide chew sticks I could try if my clean skin produces the metallic smell.