The compound with the formula Hg2Cl2 is known as mercurous chloride, commonly referred to as calomel.
Mercurous chloride is an inorganic compound consisting of mercury and chlorine. In this compound, two mercury atoms are present in the +1 oxidation state, which is why it is referred to as ‘mercurous’. The presence of two mercury atoms in conjunction with two chloride ions (Cl–) gives rise to the formula Hg2Cl2.
Calomel has historical significance and was used in medicine as a purgative and in other treatments, although such practices have largely been discontinued due to the toxic nature of mercury. In contrast, its unique properties have led to applications in various scientific fields, such as in the making of reference electrodes in electrochemistry.