How does HF react with Fe

[ESharp]

I know Hf etches alot of materials, but I can't seem to find any information on how it reacts to Fe.

[Physicsfan]

[ce]Fe + 2HF -> FeF2 + H2 ^[/ce]

[ESharp]

I'm not a chemist so could you explain that to me? What difference would be made if i added hcl aswell?

[mississippichem]

I believe HF reacts quite vigorously with most substances except for perfluoroalkanes/polymers. HCl reacts with iron to give iron chloride and H2 gas, but this reaction is very slow. The iron is passivated by a thin layer of mixed iron oxides, meaning HCl has a tough time having good collisions with iron atoms. I once put an iron nail in a glass of about 40% HCl, it took at least a few days to observe any visible change.

[ESharp]

I know HCL can be used to get rust off a nail, i was just wondering about if it was possible to use hf to get rid of the gunk that is resultant, its a solution of water and iron chloride.

[mississippichem]

Using HF will only leave you with iron fluoride gunk, which is worse. HF is some really nasty stuff, I would feel guilty reccomending its use to anyone unless it was absolutley neccessary for a synthesis. Try acetone, if that doesn't work, dilute sulfuric acid or dichloromethane might.

[Arthur Dent]

Removing iron gunk and rust might be best done with Phosphoric acid, which is much, much safer than HF. You can buy it at hardware stores in the form of a product caled "Naval Jelly" which can be applied to a rusty surface and after a while, Fe2O3 turns into FePO4 that can be easily wiped off leaving a shiny metallic surface!

 

Robert

[mississippichem]

Removing iron gunk and rust might be best done with Phosphoric acid, which is much, much safer than HF. You can buy it at hardware stores in the form of a product caled "Naval Jelly" which can be applied to a rusty surface and after a while, Fe2O3 turns into FePO4 that can be easily wiped off leaving a shiny metallic surface!

Robert

 

good call, should've thought of that one