| Popis: |
The sulfides of Fe, Co and Ni, as obtained by precipitation in aqueous solution at low acidity, are X-ray amorphous. Their Me/S ratio may be altered within very large limits by electrochemical polarization of the suspended sulfide. An apparent equilibrium potential versus the metal or sulfide ions is set up, function of the Me/S ratio. On the sulfur rich side metal depletion is limited by the segregation of rhombic sulfur; on the metal rich side the normal Me/Me++potential is reached at compositions Fe.1.04S, Co9S8, Ni3S2 above these amorphous superactive metal is deposited. The ΔG and ΔH data, obtained from half-cell voltage measurements and enthalpometric titrations, correspond with the literature values for the crystalline compounds indicating that the short-range order is similar in both. Attention is drawn to the interesting difference between the bonding of the metal partner in Co—S and Ni—S in connection with hydrometallurgical developments. |
