Lead Iodide Precipitation (Golden Rain)

Pb(NO₃)₂ + 2KI → PbI₂↓ + 2KNO₃

Overview

Lead nitrate and potassium iodide form a bright yellow precipitate of lead iodide. When the hot mixture is cooled slowly, lead iodide crystallizes as golden shimmering plates, creating the spectacular golden rain demonstration. PbI₂ has a Ksp of 9.8 × 10⁻⁹ and is more soluble in hot water.

Participants

Role	Substance	Coefficient	State
Product	Potassium Nitrate KNO₃	2	(aq)

Everyday Example

The golden rain experiment produces one of chemistry's most visually stunning displays as golden PbI₂ crystals settle like glittering snow.

Industrial Importance

Lead iodide is a precursor to methylammonium lead iodide perovskite used in next-generation solar cells with efficiency above 25%.

Properties

Type: Precipitation
Reversible: No
Energy: Exothermic
ΔH: -32.0 kJ/mol

Related Reactions

Aluminum Hydroxide Precipitation Barium Carbonate Precipitation Barium Sulfate Precipitation Cadmium Sulfide Precipitation (Yellow) Calcium Carbonate Precipitation Calcium Fluoride Precipitation (Fluorite) Calcium Oxalate Precipitation (Kidney Stones) Calcium Phosphate Precipitation (Bone Mineral) Calcium Sulfate Precipitation (Gypsum) Chromium(III) Hydroxide Precipitation

Frequently Asked Questions

What is the equation for Lead Iodide Precipitation (Golden Rain)?

The balanced equation is: Pb(NO₃)₂ + 2KI → PbI₂↓ + 2KNO₃.

What type of reaction is Lead Iodide Precipitation (Golden Rain)?

Lead Iodide Precipitation (Golden Rain) is a precipitation reaction.

Is Lead Iodide Precipitation (Golden Rain) exothermic or endothermic?

Lead Iodide Precipitation (Golden Rain) is exothermic (releases energy). The enthalpy change (ΔH) is -32.0 kJ/mol.