Filters
Results 1 - 1 of 1
Results 1 - 1 of 1.
Search took: 0.016 seconds
AbstractAbstract
[en] Radiopolarography has been applied to the study of two elements (barium and radium) which is difficult by classical polarography because of their strong electropositivity. Various parameters have been considered: nature, concentration and pH of supporting electrolyte. In any case of investigated mediums, the reduction to the metallic state reaction appeared to be reversible. An important variation of the barium half-wave potential E 1/2 with the ionic strength μ of the solution, imposed by LiCl used as supporting electrolyte, has been observed. It gives the possibility to estimate, for μ = 0, E 1/2 (Ba) = - 1.916 V/S.C.E. and E 1/2(Ra) = - 1.852 V/S.C.E. The values of barium and radium half wave potentials, obtained with a good accuracy in LiCl (or LiClO4) 0.1 M medium, have been used to establish the amalgamation energy Δ2(M) of these elements. A linear variation of Δ2(M) with the metallic radius of the 2a elements has been obtained. On the other hand, by making the concentration of the complex forming agent (Cit3-) vary in the solution, we have a shift in the half wave potential from which we can deduce the stability constant of the complexe and its composition (BaCit-; pK1=2). At last, nature and concentration of the supporting electrolyte (between 5.10-2 M and 5M) have a determining influence on the extent of the polarogram plateau. This plateau is limited by an 'hollow effect' preceding the supporting electrolyte discharge. An interpretation of this effect is suggested which is based on the Stern model
[fr]
La radiopolarographie a ete appliquee a l'etude de deux elements difficilement accessibles par polarographie classique, en raison principalement de leur forte electropositivite: le baryum et le radium. Divers parametres ont ete consideres: nature, concentration et pH de l'electrolyte support. Dans tous les cas de milieux envisages, la reaction de reduction a l'etat metallique de ces elements est apparue reversible. Une variation importante du potentiel de demi-vague E 1/2 du baryum avec la force ionique μ de la solution, imposee par l'electrolyte support LiCl (5,10-2 M < Csub(LiCl) < 45 M), a ete observee. Elle rend possible l'estimation, pour μ = 0, de E (Ba) = - 1,916 V/E.C.S. et de E 1/2 (Ra) = - 1,852 V/E.C.S. Les valeurs du potentiel Esub(1/2) de Ba et Ra, obtenues avec une bonne precision en milieu LiCl (ou LiClO4) 0,1 M, ont ete utilisees pour evaluer l'energie d'amalgamation Δ2(M) de ces elements. Une variation lineaire de Δ2(M) avec le rayon metallique R(M) des elements 2a a ete obtenue. Par ailleurs, en faisant varier la concentration d'ions complexants (Cit3-) dans la solution, on a un deplacement de E 1/2 a partir duquel on peut deduire la formule du complexe (BaCit-) et sa constante de dissociation (pK1= 2). La nature et la concentration de l'electrolyte support (entre 5,10-2 et 5 M) ont, enfin, une influence determinante sur l'etendue du palier de diffusion des radiopolarogrammes, limite par un 'effet de creux' precedant la decharge de L'electrolyte support. Une interpretation de cet effet est proposee sur la base du modele de SternOriginal Title
Radiopolarographie du baryum et du radium
Source
1979; 69 p; These (3e Cycle).
Record Type
Report
Literature Type
Thesis/Dissertation; Numerical Data
Report Number
Country of publication
ACTINIDE NUCLEI, ALKALI METAL COMPOUNDS, ALPHA DECAY RADIOISOTOPES, BARIUM ISOTOPES, BETA DECAY RADIOISOTOPES, CHLORIDES, CHLORINE COMPOUNDS, CURIUM ISOTOPES, DATA, DATA FORMS, DAYS LIVING RADIOISOTOPES, ELECTRON CAPTURE RADIOISOTOPES, EVEN-EVEN NUCLEI, EVEN-ODD NUCLEI, HALIDES, HALOGEN COMPOUNDS, HEAVY NUCLEI, INFORMATION, INTERMEDIATE MASS NUCLEI, ISOMERIC TRANSITION ISOTOPES, ISOTOPES, LITHIUM COMPOUNDS, MINUTES LIVING RADIOISOTOPES, NUCLEI, NUMERICAL DATA, RADIOISOTOPES, RADIUM ISOTOPES, SPECTRA, YEARS LIVING RADIOISOTOPES
Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue