Is calomel truly a poison and what happens when it enters the human stomach? A study from the thermodynamic viewpoint

Abstract

The chemical and electrochemical equilibria involving mercurous and mercuric chlorides in the conditions, corresponding to the human stomach environment, were studied from the point of view of chemical thermodynamics. The Gibbs free energies of formation of various mercury and chlorine compounds, the equilibrium constants, and the electrode potentials of reactions involving these compounds at 37°C were calculated. The potential-pH diagrams of Hg22+-H2O,${\rm{Hg}}_2^{2 + }{\rm{ - }}{{\rm{H}}_2}{\rm{O,}}$ Cl--H2O, and Hg22+-Cl--H2O${\rm{Hg}}_2^{2 + }{\rm{ - C}}{{\rm{l}}^{\rm{ - }}}{\rm{ - }}{{\rm{H}}_2}{\rm{O}}$ systems were plotted. The question of how toxic is calomel when ingested was discussed.

Keywords

• calomel
• human stomach
• mercury chlorides
• pourbaix diagram
• toxicity