Interaction of basalt with orthophosphoric acid

Physicochemical modeling is used to study the decomposition of basalt by orthophosphoric acid. The equilibrium compositions of the liquid and solid phases of the Al-Fe-Ca-Mg-Na-Si-P-O-H system are calculated. The effects of the acid concentration and solid-to-liquid ratio on the composition of reaction products and the degrees of extraction of iron, aluminum, magnesium, calcium, sodium, and silicon into solution are determined. Conditions for selective extraction of the components into liquid phase are estimated.     

Temperature dependence of the electrical conductivity of orthophosphoric acid in porous glass

Temperature dependence of the proton conductivity of a 85 wt % solution of orthophosphoric acid in a set of porous glasses with predominant channel radii of 4.5, 9, 19, and 74 nm was studied. A method for saturating a wide-pore glass with a dehydrated acid is suggested. This method provides a conductivity on the order of 10⁻⁴–10⁻³ ohm⁻¹ cm⁻¹ in the temperature range 373–473 K.     

Synthesis of anodic silicon oxide films in water-organic solutions containing orthophosphoric acid

Variations in electrophysical properties of anodic silicon oxide at the surface of semiconductor silicon are studied as a function of the composition of electrolytic solutions containing orthophosphoric acid and the conditions of reaching the final formation potential. The optimum conditions for the formation of anodic SiO₂ coatings that include phosphorus-containing admixtures are determined, the coatings being intended for application as diffusates in nanoelectronics.     

Determination of cadmium in orthophosphoric acid by graphite furnace atomic absorption spectrometry

Summary Cadmium has been determined in analytical-reagent grade orthophosphoric acids by direct graphite furnace atomic absorption spectrometry with Zeeman background correction. The detection limit was 3.0 pg cadmium, corresponding to 1.0 g/l of cadmium in the concentrated acid. Most of the acids analyzed contained 2–5 g/l of cadmium. The method was checked using electrochemical preconcentration of cadmium, followed by flame atomic absorption spectrometry.     

The first ionization constant from 25 to 200°C and 2000 bar for orthophosphoric acid

The ionization constant of orthophosphoric acid, determined by conductivity measurements, decreased from 7.11×10^–3 at 25°C to 6.2×10^–4 mol-kg^–1 at 200°C. The pressure effect to 2000 bar was also measured and the ratio K₂₀₀₀/K₁ is 2.7 at 25°C and 3.7 at 200°C. The standard partial molar volume change for the ionization at 1 bar, , changes from –16.1 at 25°C to –33.3 cm³-mol^–1 at 200°C. The partial molar compressibility change for the ionization, , varies from –3.8×10^–3 to –8.3×10^–3 cm³-mol^–1 bar^–1 over the same temperature range.     

Esterification with orthophosphoric acid of cellulose samples with different extents of structural heterogeneity

Modification of cellulose samples with different extents of structural heterogeneity by esterification with orthophosphoric acid in the temperature range 140?C160??C was studied. The reaction yielded cellulose phosphates containing 3.2?C6.0 wt % P, with the ion-exchange capacity of 2.2?C3.0 mg-equiv g^?1. Introduction of phosphorus into cellulose leads to a slight decrease in the structural heterogeneity. The polymer with the lower ordering index is characterized by the higher phosphorus content, which suggests that the reaction mainly occurs in the amorphous part of the polymer.     

Change in the volume of orthophosphoric acid solutions in the neutralization with solutions of various bases

Volume changes in the reactions of orthophosphoric acid neutralization with solutions of NaOH, NH₄OH, and tris(hydroxymethyl)methanamine in the mixed solvent H₂O-dimethylformamide were studied by dilatometric titration. Volume effects of the reaction depending on the mixed solvent composition and base strength were discussed.     

葡萄酒中微量高锰酸钾含量的测定

利用碱性氧化铝对葡萄酒脱色后,用分光光度法对其中高锰酸钾含量进行测定。在30℃、pH=8.5条件下,用4.0 g碱性氧化铝对20 m L样品进行振荡脱色2 h,脱色率可以达到95%以上,此法的测定准确度较高。     

Study of kinetic regularities and mechanism of methyl methacrylate radical polymerization in the presence of orthophosphoric acid

Photoinitiated homophase polymerization of methyl methacrylate (MMA) at 25°C in the presence of a complexing agent, orthophosphoric acid (H₃PO₄), was studied. It was found that in addition to the increase in initial polymerization rates and molecular weights of PMMA the system MMA/H₃PO₄ reveals postpolymerization that does not retard with time and is accompanied by an increase on average molecular weight. Macroradicals, lifetimes of which grow considerably in the presence of the complexing agent, are shown to be responsible for the termination-free postpolymerization in this system by the living chain mechanism. The effect of various factors on the kinetics of postillumination polymerization was studied. A drastic decrease in the rate of bimolecular termination of poly(methyl methacrylate) radicals was shown to be related to the change in conformational properties and to the association of propagation chains via complexing with H₃PO₄. The mechanism of polymerization in this system was discussed.     

Temperature dependence of protonic conductivity of porous glasses saturated with solutions of cesium dihydroorthophosphate in orthophosphoric acid

Wide-pore-glass plates saturated with solutions of cesium dihydroorthophosphate in orthophosphoric acid demonstrate a monotonic rise in the protonic conductivity in the temperature range 373–523 K, with σ ≥ 10^–2 Ω^–1 cm^–1 reached.     

Thermodynamics of aqueous solutions of orthophosphoric acid from the freezing point to 298.15°K

The osmotic coefficients of aqueous phosphoric acid have been determined at 298.15°K, at 273.15°K, and at the freezing point, and for concentrations from about 10^?4 m to 15 m. Phosphoric acid is incompletely dissociated even at very low concentrations, but it was possible to derived mean activity coefficients for the species H⁺ and H₂PO ₄ ^? by treating phosphoric acid as a 1-1 electrolyte.     

Chemical forms of iron(III) in solutions of orthophosphoric acid as probed by electronic absorption spectroscopy

It has been demonstrated that a combination of H₂O and H₂PO ₄ ^? groups in the coordination sphere of iron(III) complexes leads to the bathochromic shift and changes the shapes of the ⁶ A _1g ⁶ S-⁴ A _1g , ⁴ E _g transition band and charge transfer bands, whereas the substitution of phosphate ligands for all water molecules does not lead to such changes. The stabilization energies of aquaphosphate complexes have been calculated from the low-energy shifts. Spectrochemical parameters of iron(III) phosphate complexes have been determined.     

Structure of orthophosphoric Acid-N,N-dimethylformamide complexes

Ab initio calculations weere used to obtain the characteristics of the most stable configurations of the (H₃PO₄)₂, DMFA-H₃PO₄, and DMFA-(H₃PO₄)₂ complexes in a vacuum. The changes in the geometric parameters in this series of complexes were analyzed and the energies of intermolecular interactions were estimated. The DMFA-(H₃PO₄)₂ complex was found to be most stable. It was established that the hydrogen bond between the DMFA and H₃PO₄ molecules is formed with the participation of both lone pairs of the oxygen atom of the DMFA molecule.     

The Permanganate Oxidation of Triethylamine; Evidence for the Formation of Manganate Ion in Potassium Permanganate/Triethylamine Reagent

The active oxidant of KMnO_4/Et₃N reagent has been verified as potassium manganate by ultraviolet spectrometry, and the final oxidation product as manganese(IV) oxide by iodometric titration.     

Composition of phosphoric acid solutions obtained when orthophosphoric acid is used as solvent for iron-containing samples by heating: The influence of nitric acid, sulphuric acid and iron(III)

The dissolution of an iron-containing substance in orthophosphoric acid either alone or mixed with nitric acid or nitric acid-sulphuric acid mixture at 270-280 degrees has been examined, to determine the composition of the solutions which are used for analytical determinations. The possibility of condensation of H(3)PO(4) and formation of polyphosphoric acids during the dissolution has been proved. Solutions which may contain pyrophosphoric acid, tripolyphosphoric acid and tetrapolyphosphoric acid have been obtained. The exact composition of these solutions depends on the initial H(3)PO(4) concentration, the heating time, and, in some cases, the presence of nitric acid and sulphuric acid. It is assumed that the nitric and sulphuric acid affect the loss of water and therefore the thermal dehydration of the orthophosphoric acid during the dissolution. No qualitative changes in the phosphoric acid composition have been observed in the presence of Fe(III). Formation of Fe(III) polyphosphates is assumed.     

Preliminary Communications. Micellar phases formed by a solution of l-serine hydrochloride decylester and orthophosphoric acid

Polarizing microscope studies showed that the isotropic solution composed of l-serine hydrochloride decylester and orthophosphoric acid forms micellar cholesteric, nematic and lamellar phases, whereas the solution of the optically inactive ester gives micellar nematic and lamellar phases. The phase transitions were tentatively assigned as the result of two concurrent reactions at which ortho-phosphoserine hydrochloride decylester and orthophosphoric acid monodecylester are produced. Dilution of the optically active and the optically inactive lamellar phases with water gave a cholesteric and a nematic phase, respectively. The nematic director is aligned perpendicular to the glass plate, whereas that of the cholesteric phase is aligned parallel.     

Permanganate oxidation of glycine: Influence of amino acid on colloidal manganese dioxide

Permanganate ion oxidizes glycine in phosphate buffered solutions, and the product obtained was identified as a soluble form of colloidal manganese dioxide. The influence of glycine on the colloidal product shows glycine concentration changes extinction coefficients of the colloidal product, and only when the influence of glycine has been eliminated, the theoretical and experimental reaction rates coincide. The dependence of the rate of flocculation on several experimental variables was also considered.     

Double proton migrations in the associates of formic acid with nitrous,nitric, orthophosphoric,and sulfuric acids

Mechanisms of the proton transfer in dimeric associates of formic acid with nitrous, nitric, orthophosphoric, and sulfuric acids were studied by theab initio (HF/6-31G^**) method. The mechanism of the cooperative (concerted or one-step) proton transfer was shown to occur in all cases. The calculated activation barriers of the proton transfer reactions for the associates investigated are equal to 19.9, 14.2, 13.3, and 10.7 kcal mol^–1, respectively.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2184–2189, September, 1996.     

Convenient Routes for the Preparation of Barium Permanganate and other Permanganate Salts

Two convenient methods were developed to transform KMnO₄ into barium permanganate and other permanganate salts via BaMnO₄ or Mn₂O₇ intermediates. Pure BaMnO₄ was prepared by the reaction of KMnO₄ with KI in the presence of BaCl₂ and NaOH. Hydrothermal reaction of barium manganate with excess carbon dioxide for 1.5 h at 100 °C led to barium‐permanganate with almost quantitative yield. Mn₂O₇ was prepared by means of the reaction of KMnO₄ and sulfuric acid monohydrate in a two‐phase (CCl₄‐H₂SO₄.H₂O) system. In the presence of excess barium carbonate and catalytic amount of water barium permanganate could be obtained with a moderate yield. Similarly, other permanganate salts (Zn, Cd, Cu, Mg, Ca, Ni, Al, Fe, Ce, rare earth metals) were prepared by substituting the BaCO₃ for the appropriate metal oxides, hydroxides or carbonates.