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The effect of ionic strength on the rate constant ratios k(eS +Ag+)/k(eS +NzO) and k(es +H+)/ k(eS +N20) has been studied in the y-radiolysis of methanol. The different magnitudes of this effect in systems containing Ag+ and H+ ions emphasize the importance of ion size in the Brsnsted-Bjerrum treatment of ionic reactions in this solvent. The data presented are consistent with the solvated electron in methanol having unit negative charge and an effective diameter of 5 A.The Bramsted-Bjerrum theory of ionic reactions combined with the extended Debye-Hiickel theory leads to eqn. (I),where k is the rate constant of product formation in reaction (2), a,, a b and a+ are the mean effective diameters in A of the ions A% and Bzb and the activated complex respectively, p is the ionic strength, a = 1-825 x 106 (DT)-*,

Initial and final (steady-state) thermoelectric powers have been determined for the strong acids HCl, H2S04, HClO4 and HNO3 at a series of concentrations by the use of quinhydrone electrodes at a mean temperature of 25°C. From these values have been determined entropies of transport and transported entropies as well as their concentration dependence. By extrapolation the standard transported entropy of the hydrogen ion has been determined as 5-1 cal/mole deg. Support for the results has been found in other data.

The temperature dependence of the electrolytic hydrogen-deuterium separation factor, SD, was studied on bright platinum bead electrodes as a function of overpotential in 1.2N HCI-10% D20 over the temperature range of 2~176As expected, SD decreased with increasing temperature at a given overpotential. At each temperature, SD increased as the overpotential corrected for /R-drop, *lcorr, increased from 1--25 mV] to about 1--300 mVI; from --300 mV to about --500 mV, the experimental limit, (which corresponds to ~avpl --~ 1.2V) SD remained constant within the ___5% reproducibility of the measurements. This behavior is attributed to a possible change in the mechanism of the hydrogen evolution reaction as In|is increased. The temperature coefficient of SD is independent of nr within the experimental error. The Arrhenius activation energy difference between the hydrogen-deuterium and the hydrogen producing reactions, -~EA, is positive; -~EA decreases as l*lcorrl increases, but reaches a plateau value for ~corr --~1--300 mV]. Conversely, the Arrhenius pre-exponential factor ratio, AH2/AHD, increases over the same range of overpotentials before reaching a plateau value for ~corr ~ 1--300 mV[. Comparison with published work is made.Key words: hydrogen, deuterium, separation factor, isotope separation, effect of temperature on, electrolysis, water, heavy water.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 139.80.123.36 Downloaded on 2015-03-15 to IP [C.A. 57: l1901a]. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 139.80.123.36 Downloaded on 2015-03-15 to IP

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