Does Iron react differently with dilute and concentrated hydrochloric acid? A. I know that with dilute hydrochloric acid Iron (II) chloride is formed. B. I read on the internet that with concentrated hydrochloric acid Iron reacts to form Iron (III) Chloride. Could someone tell me: 1. Is FeCl3 formed as a product of reaction between HCl (conc.) and iron? 2. If yes, then what is the complete chemical reaction?