Mercuric+Chloride

Mercuric chloride, has a chemical formula of HgCl2. It's molar mass is 271.52 mg/mol and has a density of about 5.43 grams per centimeters cubed. It's melting point is 529 degrees f and the boiling point is 579 degrees f.

This chemical is very toxic, but was surprisingly used to cure syphilis until antibiotics were made.Mercuric Chloride also used to be a common component to develop negative images in photography during the 1800s. Its reaction cause the images to thicken, as well as whitened which provided a more opaque image, that was considered a positive one. While it is generally not used for these purposes anymore due to the high toxicity, it still is combined with some metals such as aluminum to cause further chemical reactions.



Photochemistry
Mercurous chloride decomposes into [|mercury(II) chloride] and elemental mercury upon exposure to UV light. Hg2Cl2 → HgCl2 + Hg The formation of Hg can be used to calculate the number of photons in the light beam, by the technique of [|actinometry]. By utilizing a light reaction in the presence of [|mercury(II) chloride] and [|ammonium oxalate], [|mercury(I) chloride] , [|ammonium chloride] and [|carbon dioxide] is produced. 2HgCl2 + (NH4)2C2O4 + Light → Hg2Cl2(s) + 2[NH4+][Cl−] + 2CO2 This particular reaction was discovered by J.M. Eder (hence the name **Eder reaction**) in 1880 and reinvestigated by W. E. Rosevaere in 1929

Preparation and reactions
Mercurous chloride forms by the reaction of elemental mercury and mercuric chloride: Hg + HgCl2 → Hg2Cl2 It can be prepared via [|metathesis] reaction involving aqueous [|mercury(I) nitrate] using various chloride sources including NaCl or HCl. 2HCl + Hg2(NO3)2 → Hg2Cl2 + 2HNO3 [|Ammonia] causes Hg2Cl2 to [|disproportionate] : Hg2Cl2 + 2NH3 → Hg + Hg(NH2)Cl + NH4Cl