Thermodynamic and Kinetic Aspects of the Stability of Sir P. C. Ray's Mercurous Nitrite Compound

Different thermodynamic and kinetic aspects of the stability of mercurous nitrite discovered accidentally in 1896 by P. C. Ray's group have been critically analysed in this review article. It has been concluded that mercurous nitrite is thermody-namically unstable but it gains the kinetic stability which may originate from the overpotential factor in the gas evolution in its redox decomposition. It may also arise from strengthening the Hg-I-Hg(I)bond which undergoes cleavage at the rate determining step (rds) in the disproportionation of Hg22+or its oxidation by the one-electron oxidant like NO2-. The Hg-1-Hg(I)bond is strengthened through the formation of the relatively weaker Hg-I-O bond (i.e. nitrito linkage) compared to the Hg-I-N bond (i.e. nitro linkage) in mercurous nitrite.