The temperatures and evaporation rates of surfactant-contaminated droplets were determined under controlled conditions. The surfactants used were sodium stearate, sodium palmitate, sodium myristate and sodium laurate. The drops were suspended on fine glass fibres or thermocouples in an environmental cell maintained at known temperature and humidity, and the evaporation rate was determined by optical measurement of the change of diameter with time. The results showed an early evaporation following a "clean" model, with a relatively sharp transition to a regime of "contaminated" evaporation kinetics. Simultaneous measurements of temperature and evaporation rate showed that the contaminants had no effect on heat transfer, i.e. their effect was limited to forming an additional mass transfer resistance. This mass transfer resistance increased strongly with initial surfactant concentration. Surfactants with longer carbon chains produced higher resistances, but after a longer delay. The partial differential equations describing surfactant diffusion within an evaporating drop were set up and solved, and an approximate analytical solution was shown to agree well with a numerical solution. By assuming that the surfactants retarded evaporation at the drop surface both by presenting a diffusional resistance to water transport and by vapour pressure lowering, a model was constructed to predict the evaporation behaviour of contaminated drops. It predicted the results obtained with sodium stearate well, but was unable to explain the results for shorter chain surfactants which were complicated by their adsorption behaviour at the surfactant-water interface. This model of single drop evaporation was extended to describe the evaporation of contaminated aerosols and used in an attempt to explain the measurements of Raper et al. (1982). Their results could not be explained quantitatively by a surfactant contaminant (though a surfactant would have produced similar qualitative features) and were probably caused by experimental error.

The heat of neutralization, ΔH_-N, of perchloric acid with sodium hydroxide has been determined at 10 and 40° in a low ionic strength, μ, region using a nonisothermal, constant-temperature-environment solution calorimeter. Correction of the data to infinite dilution by extrapolation of a plot of ΔH_-N vs μ^0.5 gives values at zero ionic strength for the heat of ionization of water of 14.216 and 12.695 kcal/mole, respectively, at 10 and 40° . The data are correlated with those of earlier workers to give an equation allowing the calculation of the heat of ionization of water at zero ionic strength over the temperature range 0-55°. The heat of reaction of tris(hydroxymethyl)aminomethane (THAM) with 0.1 M hydrochloric acid solution has been determined calorimetrically at 10, 25, and 40° C. The experimental conditions suggested by the Standards Committee of the U.S. Calorimetry Conference were followed. ΔH values of -7.644 ± 0.014, -7.104 ± 0.008, and -6.555 ± 0.012 kcal/mole at 10, 25, and 40° C, respectively, are reported. Results of the study are compared with those of other workers, and THAM is recommended for use as an interlaboratory comparison standard for solution calorimetry.

Values of thermodynamic equilibrium constants were obtained by potentiometric measurements with a Beckman Model GS pH meter in aqueous solutions for the following reactions: 1. The step-wise dissociation or protons from CH_3CHNH_3COOH^+ and C_6H_5CH_2CHNH_3COOH^+ at 0, 10, 20, 30, and 40°C. 2. The step-wise formation of bis-alamino copper(II) and bis-phenylalanino copper(II) at o, 10, 20, 30, and 40°C. 3. The step-wise formation of tris-acetylacetonato iron(III) at 30°C. Enthalpy and entropy changes were calculated for the reactions in 1 and 2, above, from the temperature dependence of the equilibrium constants. Measurements were made and data obtained for the reactions in 3 at several different ionic strengths, metal ion concentrations, and pH values. It was found that the addition of a phenyl group to alanine lowers the pK of dissociation of both protons from the acid species of the amino acid. This is attributed to the attraction which the phenyl group has for electrons. The same effect caused the log K of the first step-wise chelate of copper(II) to be lower with phenylalanine than with alanine. The second step-wise chelate of copper(II) with phenylalanine, however, has a higher log K value than the equivalent alanine chelate. This shows that the phenyl group influences the electronegativity of the copper(II) ion in the first chelate. The calculated formation constants of tris-acetylacetonato iron(III) were independent of metal ion concentration and ionic strength but increased as the pH of the measurements decreased. This was attributed to hydrolysis of the iron(III) ion. It was shown that at least qualitative measurements of equilibrium constants maybe made at pH values as low as 1.5 with a Beckman Model GS pH meter. There was no measurable increase in the proton concentration when Fe^+++ was added to solutions containing glycine or alanine. It was concluded from this that chelation does not occur to any great extent between Fe^+++ and these amino acids, although it has recently been reported in the literature that strong chelates are formed between Fe^+++ and simple amino acids. It is possible that complexes, but not chelates, are formed in the reactions of F^+++ with simple amino acids. The reaction of dilute perchloric acid with certain metal ions produces a small amount of Cl^-, indicating that an oxidation-reduction reaction occurs between the perchlorate ion and the metal ion. It was previously thought that dilute perchloric acid is not an oxidizing agent. Most of the calculations necessary in processing the data obtained were programmed for the IBM 650 computer.

No description available.

No description available.

Gas phase kinetics and thermochemistry of several halogenated species relevant to atmospheric, combustion and plasma chemistry were studied using experimental and ab initio theoretical techniques.

Call number: LD2668 .T4 1962 A35

The present work examines line measurements of pressure, temperature, and density in high speed, non-isobaric flows emanating from an underexpanded jet nozzle. Line images of rotational and vibrational Raman spectra are collected for a 8-mm linear laser probe, and are combined onto the same EMCCD detector. Combining the two techniques allows for a single-shot measurement of major species, pressure, and temperature in a turbulent non-isobaric environment that is chemically reacting. Temperature measurements along the laser test section are extracted from the rotational Raman spectrum, whereas major species densities are measured by examining the intensities of their respective vibrational Raman lines. Pressure can be calculated using an equation of state, in every location along the linear laser probe. The technique feasibility is examined by performing measurements of pressure, temperature and density in a non-reacting underexpanded air jet where the chemical composition is constant and known. Future work will extend the technique to chemically reacting supersonic flows with unknown chemical composition.

No description available.

Thesis (Ph. D.)--State University of New York at Binghamton, Department of Geological Sciences and Environmental Studies, 2007. / Includes bibliographical references.