Original: The iron compounds produced on the largest scale in industry are iron (II) sulfate (FeSO4 Â 7H2O) and iron (III) chloride (FeCl3).
Simplified: Iron also reacts with the halogens to make iron (III) halides, like iron (III) chloride. Iron reacts with the hydrohalic acids to make iron (II) halides like iron (II) chloride.