Abstract
The elution behaviors of molybdate and tungstate through anion exchange column have been investigated in the various concentration of hydrochloric and perchloric acid. A discussion is made to evaluate the existing these equilibrium and constant according to acidity. In both acids of 0.01-2.0 M concentration range, the existing equilibrium for molybdate and its constant calculated at $20^{\circ}C$ is $10^{18.9}$ for $Mo_8O_2^{4-} + 20H^+ {\rightleftharpoons} 8MoO_2^{2+} + 10H_2O$. In the 3-3.5 M hydrochloric acid it is 0.16 for $MoO_2Cl_2 + Cl^- {\rightleftharpoons} MoO_2Cl^{3-}$ and for the case of tungstate, in the both acids of 0.01-1.0 M concentration range $10^{6.6}$ for $W_{12}O_{39}^{6-} + 6H^+ {\rightleftharpoons} 12WO_3{\cdot}3H_2O$. In higher concentration than 1.0 M both acids the following equilibrium seems to be existed. $12WO_3{\cdot}3H_2O {\rightleftharpoons} 12WO_3 + 3H_2O$