Top 8 experimetns with iron wool

Which experiment with iron wool is your favorite?

Safe­ty pre­cau­tions

At­ten­tion! All ex­per­i­ments are per­formed by pro­fes­sion­als. Do not at­tempt.

Process de­scrip­tion

Iron wool is made up of thin iron threads, which are eas­i­ly heat­ed and ox­i­dized. Burn­ing ac­cel­er­ates in pure oxy­gen, as this al­lows oxy­gen mol­e­cules to hit the iron’s sur­face more of­ten than they would in or­di­nary air. This process yields iron(II,III) ox­ide, which is heav­ier than iron and mag­ne­tizes worse than the pure met­al. When elec­tric cur­rent pass­es through iron wool, heat is re­leased, which sets the wool on fire. When a piece of iron wool is heat­ed with sul­fur pow­der in a test tube, sul­fur va­por hits the cold test tube walls in a par­tic­u­lar way, which re­sults in a flute-like sound. In wa­ter, iron re­acts with dis­solved oxy­gen, yield­ing in­sol­u­ble iron(III) ox­ide. In turn, it re­acts with potas­si­um hex­a­cyano­fer­rate(II) and sul­fu­ric acid to form the blue pig­ment “Prus­sian blue.” Iron is a more ac­tive met­al than cop­per, so cop­per(II) ions in the cop­per(II) sul­fate so­lu­tion ox­i­dize it, yield­ing cop­per and iron(II) sul­fate. If a potas­si­um hex­a­cyano­fer­rate(III) so­lu­tion is added, the blue pig­ment “Prus­sian blue” is formed once again. The rigid, fi­brous struc­ture of iron wool al­lows it to me­chan­i­cal­ly re­move var­i­ous con­tam­i­nants from hard sur­faces.

A safer ver­sion of this ex­per­i­ment is in­clud­ed in the “But will it burn?” set from the MEL Chem­istry sub­scrip­tion.