Sciencemadness Discussion Board

Classic S + Fe --> FeS reaction - pyrophoric

fdsailor - 24-5-2015 at 20:38

Hello all - I figured I would ask a stupid question rather than take a risk.

In the past (multiple times) I have done the lab / demonstration where one starts with powered iron, sulfur and in a small borosilicate test tube produces FeS (I usually use a slight excess of sulfur to better ensure the iron mostly gets consumerd) Classic elements / mixture / compound demonstration.

The question I have is that from what I read, FeS can be pyrophoric in powdered form. Usually in the experiment you break open the test tube, and smash it up a bit (so you can put a few grains in some dilute HCl, and test it with a magnet.)

I have never had any problems before, but... any chance of the FeS igniting on me on grinding (or rather smashing - its pretty hard stuff)?

Thanks!

Deathunter88 - 25-5-2015 at 00:44

Even if you hit it really hard, the chances that you will reduce it to a particle size small enough for it to catch fire is small. Also, even if it does catch fire, its not much of a hazard as the quantities are so small.

macckone - 25-5-2015 at 08:19

Anything is possible if you grind it fine enough and generate enough heat while grinding. But the chances of it happening are exceedingly low. Also oxidation of FeS is not energetic, the product of SO 2 is not horribly toxic. Not that it can't kill you but a reasonable person isn't going to breath in that much due to its irritant nature.