Hydrolysis of the thorium(IV) ion in sodium nitrate medium

The hydrolysis of the thorium(IV) ion in sodium nitrate medium was studied by the emf method at 25 °C. The data show that the extent of the thorium hydrolysis depends both on the concentration of thorium and the sodium nitrate medium. Thus, at a definite pH, the extent of the hydrolysis of thorium increases with increasing its concentration, but decreases with increasing concentration and the hydration energy of the medium ions. The stability constants of complexes Th 2 (OH) 2 6+ , Th 3 (OH) 5 7+ , and Th 6 (OH) 15 9+ also slightly differ going from one concentration of sodium nitrate to another. The observed effect of the medium is in agreement with the linear free energy relationship proposed for the metal ion hydrolysis.