ON THE HYDROLYSIS OF NIOBATES IN 3M K(CL) MEDIUM,

The primary object of the work was to decide whether hexa- or pentaniobates predominate in solution. A series of emf-titrations were carried out in which the total niobium concentration, B, was kept constant whereas the total OH--concentration in excess over NbOH5, --H, was varied. The variation of the activity factors was minimized by adding KCl to the solutions and keeping K 3 M. OH- was obtained from the emf of the cell --Pt, H2 1 atm niobate solution SSE where SE is the reference electrode. From B, --H and OH- the average negative charge per Nb atom was obtained as Z --H--OH-B. Extracted