Gordon Atkinson

Ion Association of LiI in p‐Dioxane—Water Mixtures. I. Conductance Measurements

The conductance of LiI has been measured in p‐dioxane—water mixtures at 25° over the composition range 0%—95% dioxane. The data were analyzed using the Fuoss—Onsager theory to give Λ0, aJ, and KA parameters. Although aJ remains constant over the whole composition range, the Walden product decreases monotonically. Both the Stokes radius and the association constant show markedly different behavior in the range over 80% dioxane.

The CO2-water system. I. Study of the slower hydration-dehydration step

Using pressure-jump, concentration-jump, and stopped-flow methods, we have studied the rate of dehydration (k−1) of carbonic acid as a function of temperature (0–40°C) and ionic strength (0.005–3M NaCl, 3M LiBr) in both H2O and D2O. A new design of pressure-jump cell with reliable temperature control, as well as improved sensitivity in the spectrophotometric detection for stopped flow, enabled k−1 values to be determined with an accuracy better than ±8%, based on a comparison of results obtained using five different techniques. The influence of ionic strength, temperature, and isotope effects are discussed.

An Apparatus for the Determination of Rates of Proton Transfer and Other Very Fast Reactions

SUMMARY An apparatus designed to study the kinetics of very fast reactions, such as proton transfer, using an electric field jump (E-jump) relaxation technique is described. A 10-kV square wave pulse with a pulse duration of 3 μsec is used as the perturbing force. The increase in degree of dissociation of a dilute solution of a weak electrolyte can be followed directly upon application of the pulse. Secondary effects are canceled out by means of a suitable difference method in which the difference in signals is analyzed by a differential amplifier and displayed as an oscilloscope trace. Relaxation times on the order of 10-7 sec, yielding second-order rate constants of 1010 liter mole-1 sec-1, can be investigated by this method.

Simulation of sound absorption spectra of seawater systems

Sound‐absorption spectra of three chemical systems (I: CO2/H2O, II: Mg++/CO2/H2O, III: Mg++/SO4=/CO2/H2O) are simulated on a computer using available, and estimated kinetic and thermodynamic data. System III is used as a simplified model for seawater and is described by a nine‐state mechanism. Using the chemical‐relaxation theory described, six nonzero relaxation times are obtained for III. The relaxation frequency and absorption amplitude of two of the times agree reasonably well with oceanic data, which indicate excess sound absorption in the 1–5‐ and 150‐kHz frequency regions.

Pressure Jump Apparatus for the Study of Fast Reactions

ABSTRACT Fabrication of a new pressure jump cell made entirely from Plexiglas is described. Chemical relaxation effects greater than 50 μsec can be measured when the pressure on a chemical system is suddenly released from 40 atm by means of a bursting phosphor-bronze diaphragm and the resulting conductance change is measured by a Wheatstone bridge arrangement.

Possible Chemical Explanation for Low‐Frequency Absorption in the Sea

Compilation of low‐frequency sound absorption data in the ocean seems to show excess absorption at frequencies below 10 kHz. Here, by excess, we mean absorption in excess of that expected from the high‐frequency relaxation spectrum due to MgSO4 ion association. The excess can be fitted to a single relaxation with a relaxation frequency of 1.25 kHz. We have postulated that the above phenomenon is real and due to another chemical equilibrium or set of equilibriums. Using computer techniques that view the ocean as a set of coupled chemical equilibriums, we have calculated the equilibrium concentrations of all the major species. We have then examined the important equilibriums that could give rise to such a low‐frequency relaxation. Using chemical knowledge about the kinetic and thermodynamic parameters of these equilibriums, estimates of expected relaxation frequencies and amplitudes can be made. The only equilibriums that could give rise to the anomalous relaxation seem to be those that involve association ...