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Item Reactions of some simple α- and β-hydroxyalkyl radicals with Cu2+ and Cu+ ions in aqueous solution: A radiation chemical study(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (3), 1978) Buxton, George V; Green, John CItem Ionization of Moderately Strong Acids in Aqueous Solution: Part 2—Further E.m.f. Studies of the Dissociation of the Bisulphatc Ion(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (1), 1973) Covington, A. K.; Dobson, J. V.; Srinivasan, K. V.New measurements on the cell: Pt,H2 | Na2SO4, NaHS04, NaCl | AgCl | Ag have failed to substantiate the original measurements made by Hamer forty years ago and subsequently reanalyscd many times. The range of values for the dissociation constant of the bisulphatc ion (K2 of sulphuric acid) is substantially in agreement with that obtained from the simpler cell in which sodium chloride was omitted and the mercury-mercury(I) sulphate reference electrode was used. K2 = 0.0113 ±0.0005 mol kg-1 at 25°C where the uncertainty arises from a range of reasonable choices for the ion-size parameter.Item Molar Conductivity of Sodium Fluoride in Aqueous Solution at 25°C: Applications of Pitts’ Conductivity Equation(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (4), 1972) Duer, Wayne C.; Robinson, R A; Bates, Roger G.The conductivity of aqueous solutions of sodium fluoride at 25°C has been measured over the concentration range 103c= 0.8–200 mol l.–1 The results for this salt and for five other electrolytes have been analyzed by means of Pitts' full equation, modified to allow for possible incomplete dissociation of the electrolyte. The dissociation constant of a weak electrolyte such as acetic acid can be determined uniquely, independent of the value of the distance parameter a, assigned to it in Pitts' equation. But with less associated electrolytes the dissociation constant KD depends on the value of a which is used; reasonable values of a(3–7 Å) give values of KD for iodic acid between 0.165 and 0.155 mol l.–1 Potassium hexafluorophosphate and sodium fluoride, and even hydrochloric acid and potassium chloride, can be treated as associated electrolytes; only for an electrolyte such as hydrochloric acid, for which there is independent evidence of virtually complete dissociation, can an unequivocal assignment to the class of “completely dissociated electrolytes” be made. For potassium fluorophosphate and sodium fluoride, activity coefficient data suggest that treatment as moderately associated salts is to be preferred.Item Ionic Conductances in Aqueous Solution and an Empirical Conductance Equation(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (6), 1972) Davies, Cecil W.Calculations of ionic conductances in aqueous electrolytes show that the conductance of an ion is influenced by its partner to an extent depending on the mobility difference. The effect is not shown by the conductance of the electrolyte, so conductance theory should be tested against ionic conductances. An empirical equation expresses ionic and salt conductances up to 0.1 M without the aid of arbitrary parameters.Item Excited Singlet and Triplet pK Values of Xanthone in Aqueous Solution(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (6), 1972) Ireland, J. F.; Wyatt, P. A. H.Xanthone, which Ikis a ground state pK of -4.1, is shown to have a pK^j) value of +0.96 by fluorescence intensity measurements and a pK(7\) of +3.0 by triplet-triplet absorption measurements. The unusual order pK(7\) >pK(5i) >pK(5’0) is also reproduced in the Forster cycle values calculated from the absorption, fluorescence, and phosphorescence maxima, though the numbers thus obtained for pK(Ti) and pKGS^) arc 2 to 3 units more positive. Forster’s Cycle applied to the triplettriplet absorption spectra of the protonated and unprotonated species indicates that pK(T2) is —0.7, so that in basic strength the second triplet state lies between So and S1.Item Use of p-Nitroaniline to Determine Protonation Equilibrium Constants of Oxygen-containing Molecules in Aqueous Solution(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (6), 1972) Wells, C. F.Thccriticismscontaincd in a recent paper 1 of the interpretation in termsof protonation equilibria 2,3 involving (H20)4 Haq+ of the changes in optical density of acidic solutions of p-nitroanilinc on addition of organic oxygen containing substrates arc discussed. It is concluded that the effects of activity coefficients arc too small to influence the interpretation, and it is indicated how attacking molecules distinguish between protonated and unprotonated molecules of substrate in oxidation reactions and complexing equilibria. Good agreement is obtained for protonation equilibrium constants between values from this spectrophotometric method and values obtained using a range of other independent techniques.Item Quenching Effects Upon the Life-Time of Protonated 2-Naphthamide Si in Aqueous Solution(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (1), 1972) Hussain, S. Karamat; Wyatt, P. A. H.Fluorescence life-time measurements are reported for the first excited singlet of the protonated 2-naphthamide species in acid solutions in the presence of chloride, perchlorate, and sulphamate ions. Except possibly with the sulphamate anion, the quenching effect of the hydrogen ion is much greater than that of the anions in this particular case. The life-time of [graphic omitted] in the absence of quencher is 29 ns and the quenching constant for H+, 3 × 107 l. mol–1 s–1 at 25°C.Item Reactions of the HO2 Radical in Aqueous Solution with Bromine and Related Compounds(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (8), 1972) Sutton, H C; Downes, M TA flow system has been used to produce HO2 in concentrations up to 38 µM by the radiolysis of oxygen saturated aqueous formate solutions. Rate constants for the following reactions have been obtained by competitive studies, relative to the known rate of reaction of O–2 with tetranitromethane: HO2+ Br2→ H++ O2+ Br–2k=(1.1+0.6–0.4)× 108 M–1 s–1, O–2+ Br2→ O2+ Br–2k=(5.6 ± 0.7)× 109 M–1 s–1, HO2+ Br–3→ H++ O2+ Br–+ Br–2k < 107 M–1 s–1, O–2+ Br–3→ O2+ Br–+ Br–2k=(3.8 ± 0.7)× 109 M–1 s–1, O–2+ HOBr → OH–+ O2+ Br k=(9.5 ± 0.8)× 108 M–1 s–1Item Kinetics of the Reaction between Methyl Iodide and Silver Nitrate in Aqueous Solution(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (10), 1972) Huq, RokeyaThe kinetics of the interactions between silver nitrate and methyl iodide in aqueous solution have been followed using a conductivity technique. The observed second-order rate constant increases with initial concentration of silver nitrate so as to suggest that the true order is between 2 and 3. A simple formulation of the mechanism has been proposed. There is no noticeable change in the rate of reaction due to the initial addition of the product of the reaction, viz., silver iodide. It is concluded that the reaction is essentially homogeneous and that nitrate ion takes no chemical part. The energies of activation are temperature dependent.