5895. Mercurous Iodide

Nomenclature

CAS number: 15385-57-6
Yellow mercury iodide; mercury protoiodide.
Hg2I2; mol wt 654.99.
Hg 61.25%, I 38.75%.

Properties

Bright-yellow, amorphous, heavy, odorless powder. Darkens or becomes greenish on exposure to light, HgI2 and metallic mercury being formed. d 7.70. mp 290° when rapidly heated with partial decompn into Hg and HgI2. Insol in water, alcohol or ether. Sol in solns of mercurous or mercuric nitrates; cold ammonia, its solns or alkali iodide dec it into mercury and mercuric iodide. Protect from light. “Green” mercury iodide is made from metallic mercury and iodine, the green color being due to presence of some uncombined mercury.