Chemical tan for a skeleton
How do evil spirits sunbathe on Halloween?
Evil spirits sunbathe even on Halloween – because they know their chemistry! Find out which reaction is key to their summery glow!
Warning! Only under adult supervision.
- glass bowl;
- solutions of copper(II) sulfate and potassium iodide;
- plastic toy skeleton.
Pour solutions of copper(II) sulfate and potassium iodide in a bowl with a plastic toy skeleton. The mixture will darken abruptly. Leave it for 10 hours – the skeleton turns brown.
The reaction between copper(II) sulfate and potassium iodide yields molecular iodine:
4KI + 2CuSO₄ → I₂↓ + 2K₂SO₄ + 2CuI↓
The iodine molecules easily penetrate between the plastic molecules and stay in their structure, thus changing the color of the plastic.
A similar experiment is included in the “Chemistry of materials” set from the MEL Chemistry subscription.