Mercury(II) iodide (α form)
Mercury(II) iodide (β form)
β (left) and α (right) forms
Red mercury (α form only)
3D model (JSmol)
|Molar mass||454.40 g/mol|
|Melting point||259 °C (498 °F; 532 K)|
|Boiling point||350 °C (662 °F; 623 K)|
|0.006 g/100 mL|
|Solubility||slightly soluble in alcohol, ether, acetone, chloroform, ethyl acetate, CS2, olive oil, castor oil|
Refractive index (nD)
|Very toxic (T+)
Dangerous for the environment (N)
|R-phrases (outdated)||R26/27/28, R33, R50/53|
|S-phrases (outdated)||(S1/2), S13, S28, S45, S60, S61|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Mercury(II) iodide displays thermochromism; when heated above 126 °C, it undergoes phase transition from the alpha crystalline form to a pale yellow beta form. As the sample cools, it gradually reacquires its original color. It is often used for thermochromism demonstrations.
Mercury(II) iodide is produced by adding an aqueous solution of potassium iodide to an aqueous solution of mercury(II) chloride with stirring; the precipitate is filtered off, washed and dried at 70 °C.
Mercury(II) iodide can be found extremely rarely in nature as mineral coccinite.
It can appear as a precipitate in many reactions.
- Mercury(I) iodide, Hg2I2