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The anion transference numbers of aqueous perchloric acid at 25°C have been determined from 0.01 to 0.3M by the moving-boundary method. Confirmation was obtained by cation measurements at 0.1M which showed that low values resulted if the following solution contained traces of acid. Reasons for the variation of moving-boundary measurements with current have been discussed. The transference numbers gave physically more reasonable parameters with the revised 1963 Fuoss-Onsager theory but were fitted less well by it than by the earlier Fuoss-Onsagerand Pitts theories.

Reactions in solution can be heterogeneously catalyzed not only by conductance or e. m. f. electrodes but also by precipitates formed during the titration of qliquots. Attempts to follow a Menschutkin reaction by Volhard titrations revealed serious errors caused by the catalysis of a side reaction by insoluble silver salts.

The cation- and anion-constituent transference numbers of aqueous 0.02M potassium picrate have been measured at 25°C by the moving-boundary method. The large difference (0.014) between the results and the predictions of the Debye-Huckel-Onsager theory, and similar anomalies in the literature, are consistent with the existence of picrate ion dimers (Pi22−) with a formation constant of 4(±2) liter-mole−1.

Summary The rate of leaching of lead from platinized platinum electrodes has been studied, and was found to require the presence of both acid and oxygen. The results indicate that only the lead in the top 2 or 3 atomic layers of the deposit dissolves and that it is largely present there in the form of PbO; most of the dissolution occurs within an hour. The potentials of lead-containing platinized platinum electrodes behave in a non-Nernstian manner in the presence of lead nitrate.

Summary The variation of the mass specific area of platinized platinum with deposition potential from −56 to +594mV (NHE) has been studied at constant mass degrees of platinization (10 and 5 mg cm−2). Maximum mass specific area was obtained at a deposition potential of approximately, 150 mV (NHE) where the average current density of platinization was ca. 27 mA cm−2. At deposition potentials more cathodic than about 140 mV (NHE) a coupled reduction reaction led to the simultaneous evolution of hydrogen. This was accompanied by a sharp drop in mass specific area. The coulombic efficiency of the deposition process passed through a maximum, as predicted1, at a potential of about 120 mV (NHE).

Computer calculations have been carried out to test how well the variation with concentration of moving boundary transference numbers is described by 3 theories: the standard Fuoss–Onsager transference equation, a transference equation based on the revised 1963 Fuoss–Onsager electrophoretic expression, and the Pitts conductance equation arranged into its transference form. The fit of all three theories leaves something to be desired. Many aqueous transference data are less than adequately described by the theoretical equations, and several sets of non-aqueous results are fitted well only by use of distances of closet approach (a) that are physically unreasonable, even absurd. The revised Fuoss–Onsager theory often produces more sensible a values but at the price of poorer fitting to the experimental data. Suggestions are made as to why the theoretical equations apply less well to transference numbers than they do to conductances.

It has been shown that, contrary to common belief, the more accurate Fuoss and Onsager (1963) electrophoretic term often differs significantly from the term B2√c/(1 +κa) normally employed in the conductance equation. The 1963 term incorporates a complex function F(b) for which an extended and revised numerical table is given.

The viscosity Bη coefficients of 18 solutes in 100 % sulphuric acid at 25°C have been calculated from the published viscosity data of Gillespie and Wasif. Seven of the solutes possess negative Bη coefficients indicative of structure-breaking.

Computer calculations have been carried out to test how well the variation with concentration of moving boundary transference numbers is described by 3 theories: the standard Fuoss–Onsager transference equation, a transference equation based on the revised 1963 Fuoss–Onsager electrophoretic expression, and the Pitts conductance equation arranged into its transference form. The fit of all three theories leaves something to be desired. Many aqueous transference data are less than adequately described by the theoretical equations, and several sets of non-aqueous results are fitted well only by use of distances of closet approach (a) that are physically unreasonable, even absurd. The revised Fuoss–Onsager theory often produces more sensible a values but at the price of poorer fitting to the experimental data. Suggestions are made as to why the theoretical equations apply less well to transference numbers than they do to conductances.

The reduction of [Co(en)3]3+ ions in the presence of carbon black has been studied at 40 °C in aqueous solu-tions containing iodide ions. The reduction is accompanied by the oxidation of iodide ions, and no cobalt(II) is produced in their absence. Measurements have been made of the amounts of [Co(en)3]3+ and of I– ions adsorbed on the carbon surface, the variation of pH, and the effects of adding various electrolytes.

It has been shown that, contrary to common belief, the more accurate Fuoss and Onsager (1963) electrophoretic term often differs significantly from the term B2√c/(1 +κa) normally employed in the conductance equation. The 1963 term incorporates a complex function F(b) for which an extended and revised numerical table is given.

The McKay equation for radioactive exchange has been applied to optical-isomerisation reactions. A modified equation has been derived to take into account a first-order chemical side reaction. All these processes show first-order kinetics and concentration-dependence studies are required to establish the mechanism. An equation has also been derived to describe the redistribution of optical activity between bulk and adsorbed states. Experiments carried out on the racemisation of (+)589-tris(ethylenediamine)cobalt(III) tri-iodide in aqueous solution at 40 °C catalysed by a carbon black have shown the surface reaction to be rate determining. The rate is second order in adsorbed [Co(en)33+] and first order in adsorbed [I–]. The racemisation does not proceed through a cobalt(II) intermediate under the experimental conditions employed.

Co(NH3)5Br2+ in aqueous acid solution reacts more rapidly in the presence of various solids. The only effect of platinized platinum is to cause reduction of the complex to cobalt(II). With mercury(II) sulphide or silver(I) bromide present, a significant fraction of the enhanced rate is due to reduction. Addition of charcoal in various forms brings about partial reduction of aqueous Co(NO2)63– and of aqueous ammoniacal Co(NH3)63+.

The effect of over 50 different solids (including sulphides, halides, oxides, metals, and non-metals) on aqueous solutions of the salts (+)589[Co(en)3]X3(X = I or ClO4) has been investigated. The degrees of racemisation, adsorption, and reduction of the complex ion have all been followed. Thermodynamic arguments are presented that help to explain the role of the anion. The catalytic efficacies of the solids have been examined in the light of Pearson's theory of soft and hard acids and bases.