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Rust Indicator is toxic?


Primarygun
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Long time ago, I was made to carry out an experiment on the rusting of iron.

I was given potassium hexacyanoferrate(III) as rust indicator.

Is it toxic? I touched the gel with my naked hands.

Gel? I've used this stuff before and I'm almost certain it was from a dropper bottle and had a viscosity of water not gel. I think you may have mixed it with Agar gell or something. Even so They let us use it in high school and didn't give us any specific warning so yes it is toxic but I dont think you'll have any problems after touching the gell. As a matter of fact i can remeber getting this stuff on my hands too and I'm fine.

 

~Scott

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Is the conversion of hexacyanoferrate(II) ion to cyanide ion favorable?

 

Nope! The hexacyanoferrate(II)ion is a very stable komplex, which is the reason that it is almost nontoxic (or at least has very low toxicity). On the contrary, one classic way of destructing dangerous alkali cyanide spills is by adding Fe2+ (as solid FeSO4.7H2O). The ferrous ion reacts with the free cyanide ions, giving the very stable complex hexacyanoferrate(II)ion. And this has a very low level of toxicity. Even better; adding some Fe3+ and you get a precipitate of Turnbull blue (=Prussian blue), a complicated phase often described as ~KFeFe(CN)6 (s).

 

But it is possible to convert solid potassium hexacyanoferrate(II) (or hexacyanoferrate(III) ) to KCN by melting it. The potassium hexacyanoferrate is decomposed to nitrogen, ferric carbide, and potassium cyanide. And, boiling a water solution of hexacyanoferrate(II) or hexacyanoferrate(III) with acid gives gaseous hydrogen cyanide.

 

Then you are in a lot of troble!

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Nope! The hexacyanoferrate(II)ion is a very stable komplex' date=' which is the reason that it is almost nontoxic (or at least has very low toxicity). On the contrary, one classic way of destructing dangerous alkali cyanide spills is by adding Fe2+ (as solid FeSO4.7H2O). The ferrous ion reacts with the free cyanide ions, giving the very stable complex hexacyanoferrate(II)ion. And this has a very low level of toxicity. Even better; adding some Fe3+ and you get a precipitate of Turnbull blue (=Prussian blue), a complicated phase often described as ~KFeFe(CN)6 (s).

 

But it is possible to convert solid potassium hexacyanoferrate(II) (or hexacyanoferrate(III) ) to KCN by melting it. The potassium hexacyanoferrate is decomposed to nitrogen, ferric carbide, and potassium cyanide. And, boiling a water solution of hexacyanoferrate(II) or hexacyanoferrate(III) with acid gives gaseous hydrogen cyanide.

 

Then you are in a lot of troble![/quote']

 

Does it decompose in our alimentary canal by the action of acids and enzymatic reactions? or still have teh affinity to haemoglobin?

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Does it decompose in our alimentary canal by the action of acids and enzymatic reactions? or still have teh affinity to haemoglobin?

 

Highly improbable, although not impossible. Add excess ferrous sulfate, + eventually some ferric nitrate, dilute with plenty of water. Then it will be highly improbable that it will present a hazard of any kind.

 

Of course, reasonable quantities are assuemd, some hundreds of grams at most. It is unlikely to present some hazard, unless the quantity is in orders of tens or hundreds of kilograms.

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When a detective smell the special odour of cyanide' date=' he was alerted it was cyanide.

Why doesn't the detective faint?[/quote']

 

Well, you don´t faint by smelling hydrogen cyanide. I have smelled HCN from aqeous solutions, but I didn´t faint. However, in one case I was rather scared, when hexacyanoferrate in solution was heated with concentrated HCl. All of a sudden, a small cloud of moisture + HCN was formed just above the test tube! And immediately the smell of HCN spread in the room! That was really scary. But I opened the windows, after half an hour the HCN gas had gone.

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That's kind of a myth. The human nose is INCREDIBLY sensitive to many toxic compounds such as arsine, hydrogen cyanide, hydrogen sulfide, hydrogen selenide, etc. etc. Some of these compounds will numb the scent receptors so you'll soon lose your sense of smell, but in all of these compounds you can smell their presence LONG before the gases reach toxic levels. HCN has that lovely odor of bitter almonds. In my freshman year of college I had to take an inventory of our school's chemical supply, and there was a LOT of chemicals that needed to be accounted for. I must have spent four or five hours in front of the cyanide/cyanate/thiocyanate/etc. chemicals on a hot, humid day. The entire time I could smell the bitter almond odor from faint traces of HCN in the air. I had a pretty nasty headache when I was done and felt pretty tired, but I'm still alive.

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but, the detective said inhalation of a extremely tiny amount of cyanide gas can kill a person.

 

No. That "extremely tiny amount of cyanide gas can kill a person" is definitely a myth. Hydrogen cyanide is not extremely toxic. However, under some unfortunate circumstances, the death can be rapid, within minutes.

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No. That "extremely tiny amount of cyanide gas can kill a person" is definitely a myth. Hydrogen cyanide is not extremely toxic. However, under some unfortunate circumstances, the death can be rapid, within minutes.

Which cyanide is the most toxic?

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Which cyanide is the most toxic?

 

Probably hydrocyanic acid (aka. prussic acid). This acid fumes in high concentrations, so it's more likely to be accidentaly ingested, and inhalation allows the cyanide anion into the bloodstream very rapidly.

 

Next comes the soluble salts of prussic acid. These are toxic by ingestion, but with a slower onset which gives more time to administer treatment (amyl nitrite and sodium thiosulfate are given as treatment I think).

 

Cyanide containing compounds where the the cyanide anions are bound tightly as ligands are much less toxic. Iron hexacyanoferrate (the dye prussian blue) is an example.

 

By the way, bitter almond essential oil is 3 to 5 % prussic acid.

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