How to make icy patterns



Icy flowers on the window even if it’s sweltering outside? Here’s how!
Equipment and reagents: photo frame, brush, glass, 25 mL boiling water, 50 g urea.
Combine 25 mL boiling water and 50 g urea in a glass. Use a brush to apply the resulting mixture to the glass insert of a photo frame. Let dry.
Urea is an organic compound also known as carbamide or diamide of carbonic acid. It is highly soluble in water: at 20 оС (68 °F), approximately 108g of urea can dissolve in 100mL of wa­ter. When heated, urea’s sol­u­bil­i­ty in­creas­es, meaning that more of it can dis­solve in a smaller volume of wa­ter. When the solution cools, some of the urea precipitates, returning the oversaturated solution to a saturated state. When applied to a surface, the water evaporates and the urea starts to crystallize. With time, only urea crystals are left on the glass insert. Urea crystals have a needle-like structure and look like frost. Want more cool scientific experiments? Subscribe to receive MEL Chemistry sets!
Safety precautions: Only under adult supervision.

source