Edward S. Amis

A study of transference and solvation phenomena—III Lithium chloride in water-ethanol and ethanol solvents

Abstract For 99·7 weight per cent ethanol in water the transference number of chloride ion, ta, in lithium chloride decreases rapidly below a concentration of about 0·40 mole/l. It would have to decrease more rapidly at very low concentrations of salt in this solvent to check the value 0·56 recorded in the literature for ta in 0·001 to 0·0025 molar solutions of this salt in ethanol. In water fa decreases rapidly with concentration of salt in dilute solutions of lithium chloride. The Hittorf transference numbers studied here in the strongly ethanolic solvent were limited to the concentration range from 0·0714 to 0·6273 m. A discussion is given of the difference in water and strongly ethanolic solvents of the concentration dependence of fa and of tc for lithium chloride. At 1·60 weight per cent lithium chloride a linear decrease of ta with increased weight per cent ethanol was found. The causes of this increase of the relative mobility of Li+ compared to Cl− as the ethanol component of solvent increased is discussed. The grammes of solvent transferred from anode to cathode per faraday of electricity at 1·60 weight per cent lithium chloride has a sine wave-like-dependence on the weight per cent ethanol in the solvent. The frequency and the amplitude of the waves increased with increasing weight per cent ethanol. The shape of this curve is given consideration and alternate exchange of successive solvation layers of the Li+ and Cl− ions seems to be a plausible explanation.

A study of transference and solvation phenomena—I: Uranyl chloride in water, ethanol and water-ethanol solvents☆

Transference and solvation phenomena involving uranyl chloride (UO2Cl2) have been studied at 25·00 ± 0·01°C in water, ethanol and water-ethanol solvents. Transference phenomena as a function of the concentration of UO2Cl2 have been studied at the same temperature in water and in 99·7 weight per cent ethanol in water. The transference number of the anion in both water and in 99·7 weight per cent ethanol extrapolates to 0·64 and the cation to 0·36 at infinite dilution of the UO2Cl2. The transference number of the anion as a function of concentration reaches a maximum of unity at about 19·5 weight per cent UO2Cl2 and then decreases sharply with further increase of salt concentration. The maximum in water is explained as possibly arising from [UO2Cl3·solvent]− and [UO2Cl·solvent]+ ions of equal mobility. The dependence of anion transference number on solvent composition is qualitatively in agreement with the dependence, with respect to uranium (VI) ion, of the order of the electron exchange reaction between uranium (VI) and uranium (IV) ions. The plot of the moles of water per faraday transported from anode to cathode gave a sine-like curve when plotted against weight per cent ethanol in the solvent. The shape of this curve was explained on the basis of the alternate removal of layers of water of hydration on the UO2Cl3− and UO2Cl+ ions and the successive replacement of these hydration layers with ethanol.

A STUDY OF TRANSFERENCE AND SOLVATION PHENOMENA. II. SILVER PERCHLORATE IN WATER, WATER-ETHANOL, AND ETHANOL SOLVENTS

Abstract For water solvent the transference number of silver ion in silver perchlorate decreases slowly but linearly with decreasing concentration of the salt and extrapolates to 0·488 ± 0·005 at infinite dilution. This value agrees quite well with values for dilute solutions recorded in the literature. The moles of water carried per mole of cation increases with decreasing weight per cent silver perchlorate as is to be expected and is in agreement with the decrease of the transference number with increasing weight per cent ethanol. There was first a small linear decrease of transference number of the silver ion with increasing weight per cent ethanol out to about fifty-five weight per cent ethanol. Then there is an accelerated rate of decrease of the transference number up to about eighty-five weight per cent ethanol when the rate of decrease again decelerates. The solvation data indicate that silver ion carries an excess of water compared to the perchlorate ion while the perchlorate ion seems to carry alcohol molecules in an amount equal to or greater than the silver ion depending on how the basis of comparison is determined. These data might be interpreted as showing selective solvation of silver and perchlorate ions by water and ethanol, respectively.

A STUDY OF TRANSFERENCE AND SOLVATION PHENOMENA. IV. POTASSIUM CHLORIDE IN WATER AND WATER-ETHANOL SOLVENTS

Abstract Transference and solvation phenomena for the ions of cesium chloride in water have been studied. Transference of the ions of cesium chloride has also been studied as a function of solvent composition in ethanol-water mixtures up to 83 wt% ethanol. These data are presented graphically and discussed on the basis of complex ionic species and selective solvation. The cation transference number has a sine-line relationship to solvent composition that has been observed in previous studies.

The rates of the electron exchange reaction between U(IV) and U(VI) ions in water, ethylene glycol and water-ethylene glycol solvents

Abstract The rate of the electron exchange reaction between U(IV) and U(VI) ions was studied at 25° in water, glycol and water-glycol solvents, and at various concentrations of U(IV), U(VI), and hydrochloric acid. The order of the reaction with respect to each of these substances was found to depend on the composition of the solvent. The rates of the reaction in the water-glycol were slower by factors of from two to about four orders of magnitude than were the rates of the reaction in the water-ethanol and water-acetone system. This slowing down of the reaction in water-ethylene glycol as compared to water-ethanol and water-acetone is attributed to the replacement of water in the inner solvation layer of the uranyl ion by the ethylene glycol.

The rates of the electron exchange reactions between U(IV) and U(VI) ions in water and water-acetone solvents

Abstract The rate of the electron exchange reaction between U(IV) and U(VI) ions was studied at 25° in water and water-acetone mixtures containing 30, 60, and 90 per cent by volume acetone, and at various concentrations of U(IV), U(VI), and hydrochloric acid. The order of the reaction with respect to each of these solutes was found to depend strongly upon the composition of the solvent. A departure in the trend of the rate dependence on hydrogen ion concentration was found for more dilute acid concentrations in sixty volume per cent acetone. Comparisons of the kinetics of the reaction in acetone-water and in ethanol-water are made. Mechanistic and kinetic discussions are included.

The electron exchange reaction between uranium (IV) and thallium (III) in water-methanol media☆

Abstract The kinetics of the reaction U(IV) + Tl(III) → U(VI) + Tl(I) were studiedat 15, 20, and 25° in 25, 50, and 75 weight per cent methanol-water-perchloric acid solutions. Orders with respect to U(IV), Tl(III) and perchloric acid were found to depend strongly on the solvent composition. Specific velocity constants and thermodynamic quantities of activation are presented. A mechanistic expression is developed to account for these orders in 25 per cent methanol solutions. The effect of variation of ionic strength and the specific effects of various anions and cations on the rate were examined in 75 per cent methanol solutions. The salt effects are strikingly different from those found in aqueous solutions.

A study of transference and solvation phenomena—VI: Hydrochloric acid in water and water-ethanol solvents

Abstract Transference and solvation phenomena for the ions of hydrochloric acid in water, 99·7 weight per cent ethanol, and water-ethanol solvents have been studied. The transference number of the cation as a function of acid concentration in water and in 99·7 weight per cent ethanol and as a function of solvent composition are presented graphically and discussed in relation to Grotthus and ordinary conduction of the hydrogen ion and in relation to relative solvation of hydrogen and chloride ions. The amount of solvent transferred from anode to cathode is also presented graphically and discussed in relation to the transference numbers of the ions.

Kinetics of the reduction of neptunium(V) with iodide ion

Abstract The rate law for the reaction, NpO2+ + I− = Np4+ + 1 2 I 2 , may be expressed as d Np4+/dt = k[NpO2+][I−]1.5[H+]2.5. At 25† and in 3·29 M HCl, the rate constant is 10·27 × 10−2l. 4mole−4min−1. The apparent activation energy is 28,300 cal mole−1. A possible mechanism is suggested.

Kinetics of the reduction of neptunium (V) with uranium (IV) in aqueous perchlorate and chloride media

Abstract The kinetics of the reduction of neptunium (V) with uranium (IV) has been studied in aqueous perchlorate and chloride media. The reaction was found to be complex. A possible mechanism has been suggested which explains the observed kinetics in both the cases. Specific velocity constants and activation energies have been determined and compared with the values found in a separate study of neptunium (IV)-uranium (IV) reaction in similar media.