What is Mercury(II) iodide?
'''Mercury(II) iodide''', also known as '''mercuric iodide''', is a [[chemical compound]]. Its chemical formula is HgI<sub>2</sub>. It has [[mercury (element)|mercury]] and [[iodide]] [[ion]]s in it. The mercury is in its +2 [[oxidation state]]. == Properties == It is a red [[crystalline]] compound. It turns yellow when heated and turns red again when it is cooled. It is insoluble in water. It is highly toxic like all [[mercury compounds]]. == Preparation == Mercury(II) iodide is made by reacting a mercury(II) [[salt]] such as [[mercury(II) chloride]] with a source of iodide ions. This makes a bright red precipitate. == Occurrence == It is found as the very rare mineral coccinite. == Uses == It was used as a medicine, but it poisoned people who took the medicine. It is also used to demonstrate how some things change color when heated and change back when cooled. It can be used to test for [[ammonia]] and as a [[semiconductor]]. == Related pages == *[[Mercury(I) iodide]] *[[Iodine]] *[[Mercury(II) oxide]] *[[Mercury(II) bromide]] [[Category:Mercury compounds]] [[Category:Iodine compounds]]