Sciencemadness Discussion Board

FeS2 + HF ---> F2?

Chemiclint - 24-10-2012 at 03:10

I was doing an oxidation experiments on ground pyrite ore by bubbling O2 into a slurry of FeS2 through a glass sinter on a tube. The sinters kept blocking up after a while with pyrite. I tried to clearing the sinters in an expedient fashion by immersing them into full strength HF.

The glass tube of the sinter filled with a yellow/brownish gas which I can only presume was F2. I wasn’t about to sniff it to test and didn’t have time to investigate it further as I needed to get the sinters back into action.

Is there any other coloured gas that you can suggest it might have been? Is anyone familiar with this reaction? Could be a convenient method of forming F2 in a lab ….

tetrahedron - 24-10-2012 at 04:20

it's not so easy to produce F2

ScienceSquirrel - 24-10-2012 at 04:28

It is almost impossible to prepare flourine chemically.
I believe this is the only known way;

http://en.wikipedia.org/wiki/Fluorine#Chemical_routes

weiming1998 - 24-10-2012 at 04:36

Quote: Originally posted by Chemiclint  
I was doing an oxidation experiments on ground pyrite ore by bubbling O2 into a slurry of FeS2 through a glass sinter on a tube. The sinters kept blocking up after a while with pyrite. I tried to clearing the sinters in an expedient fashion by immersing them into full strength HF.

The glass tube of the sinter filled with a yellow/brownish gas which I can only presume was F2. I wasn’t about to sniff it to test and didn’t have time to investigate it further as I needed to get the sinters back into action.

Is there any other coloured gas that you can suggest it might have been? Is anyone familiar with this reaction? Could be a convenient method of forming F2 in a lab ….


Fluorine is only a faint yellow in colour, much fainter than chlorine. I imagine you made H2S, which became oxidized by the O2 into sulfur particles that are yellow. There were no oxidizing agent strong enough in your situation to even theoretically form F2.

Vargouille - 24-10-2012 at 10:38

Also, it's probably not a good idea to use HF for the acid wash. A strong acid works better, HCl probably being the cheapest, and won't degrade the sinters. Note that FeS2 liberates elemental sulfur under acidic conditions in contact with air (As from the mechanistic studies of this article, which also suggests SO2 formation as part of the mechanism). The gas, if it is a gas you produced, may be some sort of fluorinated sulfur oxide. I do not know of any sulfur oxides that are colored, nor of any sulfur flourides that are colored, which leaves fluorinated sulfur oxides and more complicated compounds than the ones I am familiar with.