Beautiful crystals of bright yellow colour are formed under cooling.
name: Golden rain - formation of small lead II iodide crystals from oversaturated solution when it is colded down
Wear goggles and disposable gloves. The lead nitrate solution is very toxic, be extremely careful in handling it.
Always follow general safety
recommendations. Please note that conducting chemistry
experiments you must comply with the relevant legal procedures in
Golden rain is one of the most beautiful chemical demonstrations. When Pb(NO3)2 is added to KI solution the reaction between the components takes place:
Pb(NO3)2 + 2KI → 2KNO3 + PbI2 (precipitate)
The formation of a yellow silky precipitate is observed. The solubility of PbI2 depends on temperature. At room temperature it is slightly soluble. Its solubility is ten times higher in hot water. When the test tube with the precipitate is heated it dissolves and the solution becomes clear again. By cooling the solution down we promote the formation of tiny very beautiful shiny crystals of PbI2 since the temperature decrease lowers the PbI2 solubility.