Properties and stability of supersaturated chromium amalgam

Supersaturated chromium amalgam as concentrated as 1.5 M, has been prepared electrochemically. The resulting amalgam has a mirror-like shine and behaves like plasticine. The stability of supersaturated (up to 10 mM) chromium amalgam was investigated in 1 and 5 M solutions of NaClO4, in the range of −20 to 60°C, using double potential step chronocoulometry (DPSC). The results enabled us to determine the conditions in which the oxidation of Cr(Hg) is diffusion controlled. In the millisecond time scale, this usually occurs at concentrations lower than 1 mM Cr3+ Cr(Hg) decomposes more rapidly at increased temperature and concentration of chromium in the amalgam, and, in the first stage, forms inactive clusters (probably Cr3). The energy of activation of this reaction was determined as Ea = 36.2 kJ mol .