Question: in what way is iron sulphide different from a mixture of iron and sulphur

Sarah Thomas answered on 16 Jun 2011:

Well the way that they make it is just by heating a mixture of iron and sulfur! Iron sulfide is different in a number of ways:

1) The way it looks: iron sulfide is brown crystals whereas iron is a silvery looking metal, and sulfur is bright yellow crystals.

2) Iron sulfide doesn’t burn very well, iron also doesn’t burn, but sulfur burns with a bright blue flame!

3) Iron sulfide is only naturally occuring in very small amounts but iron and sulfur can be mined in vast quantities.

4) Iron is strongly magnetc, sulfur is not magnetic at all, and iron sulfide is only weakly magnetic but only when it is in small chunks.

5) Another difference is the way they react with hydrochloric acid. Iron won’t react, sulfur just floats on top of the acid, and iron sulfide reacts vigorously and produces a rotten egg smell which is hydrogen sulfide gas.

Another random iron sulfide fact: When eggs are cooked for a long time, the yolk’s surface may turn green. This is due to iron(II) sulfide which forms as iron from the yolk meets hydrogen sulfide released from the egg white by the heat! Yuk!