Copper(II) citrate: synthesis and decomposition
An interesting experiment with copper(II) citrate
In today’s program: a cool experiment with copper(II) citrate!
Warning! Only under adult supervision.
- hot solutions of copper(II) sulfate and sodium citrate;
- filter paper;
- Petri dish;
- sheet of metal;
- paper stencil.
Add a hot solution of sodium citrate to a hot solution of copper(II) sulfate. Observe as a copper(II) citrate precipitate gradually forms. Filter it out and leave it to dry for 24 hours – it will turn into a beautiful turquoise powder. Arrange it in a paper stencil on a sheet of metal and touch it with a burning match. The copper(II) citrate will gradually turn black.
When heated, copper ions are reduced, taking electrons from citrate ions, and turn into very small particles of metallic copper. Unlike a sizable piece of copper, these particles are easily oxidized by atmospheric oxygen, releasing heat and forming black copper(II) oxide. The heat this generates keeps the process going, so even a small amount of heat is enough to cause the decomposition of the entire copper(II) citrate pile.