88 research outputs found

    The activity coefficient of sodium chloride in seawater

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    Using a sodium amalgam and silver-silver chloride electrode pair, the mean activity coefficient of sodium chloride in synthetic seawater has been compared with that in pure sodium chloride solutions. Effects of concentration and temperature were measured. The mean activity coefficient in synthetic seawater was found to be slightly higher than in a sodium chloride solution of the same ionic strength. No explanation for this is offered

    The activity coeffiicient of sodium sulfate in seawater

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    The mean activity coefficient of sodium sulfate in artificial seawater has been measured with a sodium amalgam electrode and a lead amalgam-lead sulfate electrode. The value of 0.378 at 25°C and 35‰ salinity, and other data, suggest that a considerable fraction of the sulfate ion is tied up as a sodium sulfate complex

    Phase Behavior of Aqueous Na-K-Mg-Ca-CI-NO3 Mixtures: Isopiestic Measurements and Thermodynamic Modeling

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    A comprehensive model has been established for calculating thermodynamic properties of multicomponent aqueous systems containing the Na{sup +}, K{sup +}, Mg{sup 2+}, Ca{sup 2+}, Cl{sup -}, and NO{sub 3}{sup -} ions. The thermodynamic framework is based on a previously developed model for mixed-solvent electrolyte solutions. The framework has been designed to reproduce the properties of salt solutions at temperatures ranging from the freezing point to 300 C and concentrations ranging from infinite dilution to the fused salt limit. The model has been parameterized using a combination of an extensive literature database and new isopiestic measurements for thirteen salt mixtures at 140 C. The measurements have been performed using Oak Ridge National Laboratory's (ORNL) previously designed gravimetric isopiestic apparatus, which makes it possible to detect solid phase precipitation. Water activities are reported for mixtures with a fixed ratio of salts as a function of the total apparent salt mole fraction. The isopiestic measurements reported here simultaneously reflect two fundamental properties of the system, i.e., the activity of water as a function of solution concentration and the occurrence of solid-liquid transitions. The thermodynamic model accurately reproduces the new isopiestic data as well as literature data for binary, ternary and higher-order subsystems. Because of its high accuracy in calculating vapor-liquid and solid-liquid equilibria, the model is suitable for studying deliquescence behavior of multicomponent salt systems

    Some thermodynamic properties of mellitic acid

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    The determination and occurrence of aluminum in sea water.

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    A method was developed for the determination of aluminum in sea water using oxine as a reagent. Extraction of aluminum oxinate by chloroform from acidic solution was impeded by the presence of fluoride in sea water. The fluoride Interference was less severe in basic solution and it was possible to extract aluminum oxinate from sea water at a pH of 8 with no loss of sensitivity due to the presence of fluoride. Iron and copper were complexed with cyanide in reducing solution and manganese oxinate was removed by extracting it from the chloroform into an aqueous acidic solution. Other interfering ions in sea water were present in amounts too small to be significant. The absorbancy of the aluminum oxinate complex was measured at 395 mμ and compared with a calibration curve. The aluminum concentration in sea water ranged from 2-42 μg./l. Values for coastal water were higher than for oceanic water.Science, Faculty ofChemistry, Department ofGraduat
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