Franca Castellani

Solubility data of some sodium salts in molten urea: Part I

Abstract Liquid-solid equilibrium temperatures were measured over the concentration ranges allowed by the thermal stability of urea in binary systems between the amide and some sodium salts (NaSCN, NaNO 3 , NaCIO 4 and HCOONa). Experimental results are given in terms of phase diagrams and on the basis of the trend of Δ T /(vmK) vs. m .

Acetamide-ammonium sulfamate : a reactive binary system in molten state

Molten mixtures of acetamide and ammonium sulfamate (indicated here AS) are reacted at mole fractionXAS<0.35 to produce (NH4)2SO4 and CH3CN. The experimental conditions and analytical methods adopted are given and a kinetic mechanism is proposed.ZusammenfassungAcetamid und Ammoniumsulfamat (AS) wurden in Schmelzen mit dem MolenbruchXAS umgesetzt, um (NH4)2SO4 und CH3CN zu erhalten. Es werden die angewendeten Reaktionsbedingungen und analytischen Verfahren sowie ein kinetischer Mechanismus gegeben.

Silver iodide complexes in molten acetamide

Abstract Titrations of silver by chloride, bromide and iodide ions are carried out on molten acetamide solvent at temperature of 87°C; by these data the solubility products of silver halides have been computed. The presence of the complex species AgI, AgI2− and AgI32− has been found in the reaction between silver and iodide; the relative complexation constants have been calculated by graphical and numerical methods.

Potentiometric determination of nitrite with an ammonia gas sensor

Abstract Nitrite is converted completely to nitrogen by sulfamic acid, the excess of which is determined after conversion to ammonia by acid hydrolysis. Equal aliquots of sample are treated with increasing amounts of sulfamic acid, and potentials are measured after the hydrolysis. Nitrite in the range 1.5 × 10 -5 –2 × 10 -2 mol l -1 can be determined with errors less than 2%.

Analysis of gases dissolved in a concentrated aqueous solution of sodium trifluoroacetate

Systems composed of water and sodium trifluoroacetate cannot be considered to be binary systems; in fact, oxygen and nitrogen are strongly soluble in these solutions, so that the resulting mixture shows reactive properties on organic substances. As a preliminary study, the chemical analysis of gases present in the liquid mixture composed of water and CF3COONa (mole ratio = 2.92: 1) has been carried out.The solubility of O2 and N2 at 21.5 °C and 711 Torr in an 18.9986 mol kg–1 aqueous solution of CF3COONa was measured. The result shows that these gases are strongly trapped in the employed solvent, the solubility being ∼550 times greater than in water.

Ternary system composed of H2O, N-methyl morpholin N-oxide and NaSCN: Ultrasonic investigation.

Abstract Longitudinal and transversal wave measurements in one ternary mixture composed of water, N-methyl morpholine N-oxide and sodium trifluoroacetate show aggregation phenomena. The aggregates are more stable in comparison with solutions studied previously.