Rainbow plating
Channel: MEL Chemistry
Date: 2020-05-01

How to make beautiful rainbow plating!

Equipment: copper(II) sulfate solution, metallic plate, sandpaper, adhesive stencil, bowl of water, heating device, alcohol, cotton pad, colorless nail polish.

Sand a steel plate and wipe it down with a cotton pad moistened with alcohol. Glue a stencil onto the plate. Apply a solution of copper(II) sulfate. After 10 seconds, rinse the plate in a bowl of water. Carefully remove the stencil and warm the plate on a heating device. This yields a rainbow coating, which can be preserved with a protective layer of colorless nail polish.

Coating the steel plate with the copper(II) sulfate solution results in a redox reaction in which iron, as the more active metal, displaces copper from the solution of its salt. In this case, the points of contact between the solution and the iron plate are covered with a thin layer of copper. If this copper layer is heated, a rainbow film of copper oxides appears. The color of this film varies depending on how thick it is. 

This and other safe home experiments are waiting for you in the MEL Chemistry subscription!

Warning! Only under adult supervision.