Indirect polarographic determination of stability constants

Zinc, complexes of glycollic and lactic acids were studied by an indirect polarographic method using cadmium as the indicator ion. The half-wave potentials of cadmium complexes shift to more positive values in the presence of zinc. From this shift, the formation function, -n, for zinc was obtained as a function of ligand concentration and the stability constants were calculated.     

Surface segregation and surface electronic interactions in PtCu

Photoemission and Auger electron spectroscopy on Pt_0.98Cu_0.02 show that the (110) face has over twice as much Cu surface segregation as the (111) face. The Cu 3d-derived surface “density of states” differ strikingly in peak shape and in width (by 0.5 eV). The centroids, compared with bulk Cu d states, are shifted by more than 0.3 eV towards the Fermi level. This is the first experimental correlation between surface segregation and surface bonding.     

Velocity gradient driven flute instabilities in plasmas

The effect of velocity gradient across the magnetic field on the low frequency flute modes is examined in detail, using the normal mode analysis. It is shown that some new type of instabilities driven primarily by the velocitygradient arise and these excited modes eventually attain the convective saturation. The onset of plasma turbulence due to these instabilities may possibly be one of the major contributors for anomalous heating process and enhanced plasma resistivity.     

Polarography of bismuth in oxalate and thiourea media

The polarography of bismuth in the presence of thiourea and oxalate is discussed. Measurements could not be made in thiourea medium due to the dissolution of mercury. The reduction was irreversible in oxalate medium and the kinetic parameters as well as the stability constant of the predominant species were calculated from the formal potentials measured by amalgam polarography. The mixed complexes were not formed and the reduction was quasi-reversible in the presence of both the ligands.     

The chromic acid oxidation of hydroxy acids—Catalysis by manganous ions

Kinetic data for the catalysis by manganese (II) of the chromic acid oxidation of α-hydroxy and α-keto acids over a range of Mn (II) concentrations are reported. A first order dependence on Mn(II) in the lower concentration regions with an upper limit is noticed. The results are explained on the basis of a slow rate determining decomposition of an Mn (III)—substrate complex which is formed by the oxidation of an Mn (II)—substrate species formed initially. The enhanced positive catalysis by Mn (II) in the case of Cr (VI) oxidation of pyruvic acid over that of lactic acid is attributed to an independent mechanistic path.     

On the polarography of zinc in ethylenediamine medium

Polarography of zinc in ethylenediamine medium has been carried out. The equilibrium potentials have been determined by amalgam polarography. The standard rate constant for the electrode reaction and the stability constants of the complexes have been calculated.     

Indirect polarographic determination of stability constants

The stability constants of cadmium thiosulphate complexes have been determined in 25% methanol medium. The stability constants of thiosulphate complexes of zinc and lanthanum have been determined by the indirect method using cadmium as the indicator ion.     

Effect of complexing agents on the disproportionation of uranium (V)

The effect of lactate, thiocyanate, sulphate, oxalic acid and fluoride on the disproportionation of uranium (V) formed at the dropping mercury electrode has been studied. The rate constants for the disproportionation reaction are calculated and the results are discussed on the basis of the stability of the complexes.     

Electron impact induced hydrogen migrations in organic molecules: IV—novel hydrogen transfers in alkyl o-methoxybenzoates

Simultaneous hydrogen transfers—one from the methoxy group and the other from the alkyl group—to both the oxygen atoms of the ester function result in the formation of a common ion at m/z 152 in the alkyl o-methoxybenzoates on electron impact. Expulsion of the formyl radical from this ion leads to a fragment resembling the protonated benzoic acid. Another novel feature in these compounds is the loss of H₂O from the [M? R]⁺ ion which arises through an ortho effect during a secondary fragmentation process.