Regularities of praseodymium oxide dissolution in acids

The regularities of Pr2O3, Pr2O5 and Pr(OH)3 interaction with inorganic acids are studied. pH of the solution and oxidation-reduction potential registrated at 20±1 deg C are the working parameters of studies. It is found that the amount of all oxides dissolved increase in the series of acids - nitric, hydrochloric and sulfuric, in this case for hydrochloric and sulfuric acid it increases in the series of oxides Pr2O3, Pr2O5 and Pr(OH)3. It is noted that Pr2O5 has a high value of oxidation-reduction potential with a positive sign in the whole disslolving range. A low positive value of a redox potential during dissolving belongs to Pr(OH)3 and in the case of Pr2O3 dissloving redox potential is negative. The schemes of dissolving processes which do not agree with classical assumptions are presented