Lead(II) iodide or lead iodide is a salt with the formula PbI2. At room temperature, it is a bright yellow odorless crystalline solid, that becomes orange and red when heated. It was formerly called plumbous iodide.
Molar mass：461.01 g/mol
Appearance：bright yellow powder
Melting point：402 °C (756 °F; 675 K)
Boiling point：953 °C (1,747 °F; 1,226 K)
Solubility in water：0.044 g/100 mL (0 °C)
0.0756 g/100 mL (20 °C)
0.41 g/100 mL (100 °C)
Solubility product (Ksp)：4.41 x 10−9 (20 °C)
Solubility ：insoluble in ethanol, cold HCl
soluble in alkalis, KI solution, methyl isopropyl ketone
Band gap：2.3 eV
Magnetic susceptibility (χ)：−126.5·10−6 cm3/mol
Crystal structure：Rhombohedral, hexagonal hP3
The compound currently has a few specialized applications, such as the manufacture of solar cells and X-ray and gamma-ray detectors. It's preparation is an entertaining and popular demonstration in chemistry education, to teach topics such as precipitation reactions and stoichiometry. It is decomposed by light at moderately high temperatures and this effect has been used in a patented photographic process.
Lead iodide was formerly employed as a yellow pigment in some paints, with the name iodide yellow. However, that use has been largely discontinued due to its toxicity and poor stability.