Equilibri di idrolisi ad alta temperatura

L’idrolisi di molti ioni metallici dà spesso luogo alla formazione di specie mono e polinucleari. Nel caso di cationi quali Ga(III), Al(III), Cr(III) le difficoltà riscontrate nella raccolta dei dati sono essenzialmente dovute alla lentezza degli equilibri in studio; ciò ha causato disaccordo tra i dati di letteratura sia sulla natura delle specie formate che sulla loro stabilità. In assenza di un opportuno catalizzatore per lo studio a temperatura ambiente, l’unico modo per aumentare la velocità delle reazioni è aumentare la temperatura, in modo tale da ottenere stati di reale equilibrio. Un aumento della temperatura rende complicata la termostatazione dei reattivi e la loro aggiunta dall’…

la semicella Zn(Hg)/Zn++ ed alcune sue applicazioni analitiche

Unusual oxidation states of cations in aqueous solutions

Trimethylplatinum(IV) complexes with ON bidentate ligands

Abstract Complexes of the trimethylplatinum(IV) moiety with bidentate monobasic salicylaldimines C 6 H 5 (OH)CHNR (R = ethyl, propyl, phenyl) have been prepared and characterized by IR, UV and NMR spectra and magnetic susceptibility measurements. The complexes are dimeric with double PtOPt bridges, and the metal appears to be pseudo-octahedrally hexacoordinated.

The complex formation equilibria between Cd(II), Pb(II) and iminodiacetic acid in NaClO4 0.93 Mw at 25°C

The Formal Redox Potential of the Ti(IV, III) Couple at 25 °C in 1 M HCl 2 M NaCl Medium

The formal redox potential of the Ti(IV, III) couple has been determined at 25 degrees C in 1 M HCl, 2 M NaCl aqueous medium, by emf measurements of a junction-free cell with glass and mercury electrodes. Ti(III) and Ti(IV) concentrations were changed by controlled electrolysis. The mean value of the searched formal potential, in a large range of total titanium concentration, is 9 +/- 1 mV against the molar hydrogen electrode in the same ionic medium.

Le proprietà acide dello ione uranile in soluzione acquosa LiClO4 3,6 molale a 75 e 100°C

Chelating behaviour of diacetylbisbenzoylhydrazone with SnIV, PbII and PbIV

Determinazione spettrofotometrica simultanea della durezza calcica e totale in acque potabili

The Formal Potential of the Ti(IV-III) Couple at 25°C in the TiCl4, TiCl3, HCl, NaCl Mixtures at 3 M tital Cl-.

The acidic properties of the uranyl ion in LiClO4 aqueous solutions 3.6 molal at 75 and 100°C

Adduct formation by sub-coordinated metal complexes—VI. Synthesis and pyridine adducts of some nickel(II) chelates formally tri-coordinated

Voltammetric determination of platinum il leaves of Nerium oleander L. ; Preliminary data on assessment of air quality in the Palermo

Stati di ossidazione insoliti di cationi metallici in soluzione acquosa

Complex Formation of the Uranyl (UO22+) Ion with the Diethylene Triaminopentaacetate (DTPA) Ligand at 25 °C in 3 M Sodium Perchlorate

The complex formation between the uranyl (UO22+) ion and the diethylene triaminopentaacetate ligand (DTPA) has been investigated at 25 °C, in a 3 M sodium perchlorate medium. The overall protonation constants βjH of the free ligand have been previously determined in this ionic medium: six protonated species (HjA), with j ranging from 1 to 6, together with the free anion A5− have been identified in the concentration range from (3·10−3 to 13·10−3) mol·kg−1. Four complex species, H2UO2A−, HUO2A2−, UO2A3−, and UO2AOH4−, have been identified in the total uranyl concentration range from (1.1·10−3 to 5.7·10−3) mol·kg−1, and their overall stability constants determined, keeping the metal to ligand …

The formal redox potential of the Yb(III,II) Couple at 0°C in 3.22 molal NaCl medium

Following our previous investigations on aqueous solutions of hypooxidized and iperoxidized species, we managed, by lowering the temperature of the solutions to 0 degrees C, to obtain, by electrochemical methods, Yb(II) and Yb(III) mixtures, enough stable to determine by a potentiometric method the formal redox potential of the Yb(IlI, II) couple. Its value, in a large range of total Ytterbium concentration, is -1233 +/- 3 mV against the molal hydrogen electrode in the 3.22 m NaCl medium.

Il potenziale formale della coppia Ti(IV,III) a 25°C nel mezzo HCl 1 M NaCl 2 M

Nell’ambito delle diverse coppie ossidoriduttive di un elemento in soluzione acquosa, vengono indicate come ipoossidate le specie appartenenti a quelle coppie il cui potenziale standard è inferiore a quello di riduzione dell’acqua ad idrogeno, e come iperossidate le specie che fanno parte di coppie con valore del potenziale di riduzione superiore a quello dell’ossigeno ad acqua. Si tratta in entrambi i casi di specie termodinamicamente poco stabili che si trasformano rispettivamente nella forma ossidata con evoluzione di idrogeno e nella forma ridotta con evoluzione di ossigeno. Tali processi sono modulati dall’attività idrogenionica della soluzione (Figura 1). Figura 1. Intervallo di stabi…

The possible use of the half cell Zn(Hg)/Zn2+ in ionic equilibria studies

Dioxouranium(VI) hydrolysis at 75 and 100°C in 3.6 molkg-1 LiClO4

This work concerns the acidic properties of uranyl ion UO22+ at 75 and 100 °C in 3.6 molal (molkg-1 solvent) LiClO4 aqueous medium. The investigation was carried out by a coulometric-potentiometric technique. Direct and reverse acid base titrations were carried out in order to check the achievement of actual equilibrium conditions. Moreover, in order to reveal oversaturation conditions, a further check was carried out on clean saturated hydrolyzed solutions.

Gli spot test nell'analisi sistematica di alcuni cationi

Batch experiments for the determination of the Ti(IV,III) couple in 1 moldm-3 HCl, 2 moldm-3 NaCl medium at 25°C

The determination of the Ti(IV, III) redox couple formal potential in 1 M HCl 2 M NaCl medium at 25°C through batch experiments involving the preparation of Ti(IV) and Ti(III) mixtures via the reaction of Ti(IV) with Zinc amalgam, has been carried out with emf measurements in order to verify the correctness of the previous value that the authors obtained by a coulometric-potentiometric investigation in the same conditions. The results from the two independent methods are in good agreement: 9 ± 1 mV the first and 9 ± 2 the average batch result.

Il potenziale redox della coppia Ti(IV,III) a 25°C nel mezzo HCl 1 M NaCl 2 M

The determination of mineral acidity excess in solutions containing Ga(III), Al(III), Bi(III)

Abstract A new procedure is proposed to carry out volumetric determinations of the strong acid content of a solution in the presence of inorganic cations such as Ga 3+ , Al 3+ , Bi 3+ which, showing in aqueous solution an acidic behaviour, introduce non negligible interferences in these determinations. Before the acid–base titration, an equivalent amount of a ligand, such as dihydrogen ethylendiamino tetraacetate is added, in order to strongly complex the cation masking it toward the successive addition of a strong base. Interferences are thus removed, and the volumetric determination of the strong acid excess plus the hydrogen ions set free from the ligand, as a consequence of the complex …

The complex formation equilibria between Zn(II) and iminodiacetic acid (IDA) in NaClO4 1 M at 25°C

Il sistema Bismutile-DTPA in NaClO4 3 M a 25°C

The Vanadyl-Diethilenetriaminopentaacetate system in aqueous 3 M NaClO4