Spectrophotometric, Potentiometric and Effect of Chloride Ions Study on Hydrolysis of Holmium in 2 M Ionic Strength

The effect of chloride ion on holmium hydrolysis in 2M NaClO4 and 2M NaCl was studied by spectrophotometry and potetiometry. The pCH borderlines of precipitation were determined by the spectrophotometric method. The stability constant of the first hydrolytic species of holmium was determined by spectrophotometric and potentiometric pH titrations whose data were processed with the SQUAD and SUPERQUAD computer programs, respectively. The hydrolysis constants obtained were: log* 1,H = -8.02 ± 0.05 in 2M NaClO4 and log * 1,H = -8.16 ± 0.04 in 2M NaCl. The log10 1,Cl constants for the species HoCl2+ was also calculated for 2M ionic strength and 303K from the hydrolysis constant obtained in both perchlorate and chloride media. This value was log 1,Cl = -0.56.