WATCH: Mesmerising time-lapse of a copper-iron reaction

You've never seen the classic copper-iron replacement reaction quite like this. Watch this awesome time-lapse footage as iron atoms and copper ions switch positions in a copper sulphate solution.

A single replacement reaction experiment occurs where a more active element replaces a less active element in a compound. Here iron is the more active element, and copper the less active element.
By placing some thick iron wire in a copper sulphate solution, DizzyCtube at YouTube created the reaction where iron atoms leave the wire to enter the sulphate solution, while the copper ions precipitate out of the solution and onto the wire. Also known as a displacement reaction, the products of this experiment would end up as iron sulphate and solid copper.

The blueish colour of the liquid - which appears green here because of the yellow background - is due to the presence of copper ions in solution. As the reaction occurs and the copper ions precipitate out, the solution slowly loses this distinctive colour. 

"The iron atoms in the rod give up their electrons to the copper ions in solution," says DizzyCtube, "so that the iron becomes oxidised while the copper becomes reduced."