ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 27, Number 3
JKCSEZ 27(3)
June 20, 1983 

Effect of metallic salts added to the α-Fe2O3-HCl or α-Fe2O3-H2SO4 reaction systems were investigated by colorimetric and gravimetric determinations. While reductive salts exhibited remarkably enhanced reaction rate, non-reductive salts showed inhibitive results. We supposed that the improvement of dissolution rate of α-Fe2O3 by the addition of FeCl2, a reductive salt, to the α-Fe2O3-HCl system can be attributed to the formation of chloro-bridge between Fe3+ and Fe2+, and therefore some partial electronic charge transfer from Fe2+ to Fe3+ on the surface of α-Fe2O3 will be easily achieved through the bridged bond. The transferred charge to the surface will reduce the positive charge of initial Fe3+, and also result to reduce the lattice energy of that site. Assuming tothat there is a linear relationship between the lattice energy change and the change of activation energy of the reaction system, the transferred partial electronic charge to Fe3+ of α-Fe2O3 surface was calculated to be ca. 0.36e.