DIY: Fluorescence at home
An easy-to-make substance that glows in UV light
Conduct the experiment only under adult supervision.
- 1 tsp urea;
- 1 tsp citric acid;
- aluminum cup;
- wooden stick;
- container of water.
Transfer 1 tsp carbamide to an aluminum cup and place on a burner. Add 1 tsp citric acid and heat. When heated, the crystals of urea and citric acid melt. Continue heating until the mixture acquires a yellowish-brown color. Cool the resulting mixture and dissolve in water. The aqueous solution glows blue under UV light.
Nothing will happen if you dissolve a mixture of urea and citric acid in water and shine a UV light on it. However, if the citric acid and urea are fused together first, and the resulting melt is then dissolved in water, it will glow blue under UV light. When heated together, these substances form some citrazinic acid, which is what “illuminates” the solution under the UV waves. Such luminescence is called fluorescence – the rapid emission of light energy following a substance’s absorption of light or other electromagnetic radiation.