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41.
Chloramine-B has been used as an oxidizing agent in hydrochloric acid medium for the indirect volumetric estimations of hydrogen peroxide, lead dioxide, manganese dioxide, selenium dioxide, sodium formate, sodium sulphide, sodium metavanadate, potassium iodate and copper sulphate using iodine monochloride as a catalyst and pre-oxidiser. Chloroform is used as an indicator. It is coloured pink owing to the liberation of iodine during the titration and becomes light pale yellow at the end-point because of the formation of iodine monochloride. 相似文献
42.
Krishna Raman Surendra S. Parmar Shiva P. Singh 《Journal of heterocyclic chemistry》1980,17(5):1137-1139
A series of 1-(5-phenyl-2H-tetrazol-2-ylacetyl)-4-substituted thiosemicarbazids were prepared as possible antiinflammatory agents. Their antiproteolytic activity was reported. 相似文献
43.
Summary The macrocycles 2,10-dimethyl-3,4,8,9,15-pentaazabicyclo-[9.3.1]-pentadeca-1 (15),2,9,11,13-penta-ene-5,7-dione (L) and 2,11-dimethyl-3,4,8,9,10,16-pentaazabicyclo[10.3.1]-hexadeca-1 (16),2,10,12,14-penta-ene-5,8-dione (L) were prepared and characterized by elemental, i.r. and mass spectral data. The macrocycles react with various metal(II) chlorides to yield complexes of the types [MLCl2H2O] (M = Mn, Co, Ni, Cu or Zn), [MLCl2H2O] (M = Mn, Ni, Cu or Zn) and [Co3L2Cl4]Cl2. The complexes were characterized by physico-chemical and spectroscopic methods. 相似文献
44.
45.
The dielectric constant ?' and loss tangent tan δ of chlorobenzene-cis-decalin mixtures have been measured in the temperature range 77 K to 330 K and frequency range 0.1 to 100 kHz. On cooling, ?' increases with decreasing temperature upto about 135 K, after which it drops rapidly with decreasing T followed by a slow decrease. This indicates that the liquid mixture goes to an amorphous phase which transforms to a glass phase of restricted dipole rotation below Tg; however, the peak in ?' is due to relaxation in the amorphous phase (α relaxation) and does not give an exact Tg. On heating, the behaviour of the cooling curve is retraced upto 160 K, after which ?' drops suddenly to a value lower than that at 77 K in the glass phase. This indicates the transition to a crystalline phase in which dipole rotational freedom is completely lost. The crystalline phase changes to a eutectic liquid phase of high ?' at a temperature (200 K) lower than the melting point of chlorobenzene and cis-decalin. Dielectric dispersion is observed only in the glass and amorphous phases. The dielectric relaxation time is independent of the concentration of chlorobenzene. 相似文献
46.
The red complex formed by copper (II) and phenanthraquinone monothiosemicarbazone has an absorption maximum at 530 nm with a molar absorptivity of 14000 cm?1 mole?1. The pH range for the determination is 1.1–6.6. Optimum range of concentration for accurate determination is 0.50–3.47 ppm of copper (II) in 50% methanol medium. The limits of interference due to foreign ions have been studied. The method has been successfully employed for the determination of copper in various samples of milk. 相似文献
47.
The excess Gibb's free energy of mixing, GE, for ethyl iodide+toluene at 25°C have been obtained from the measured vapor pressuure data. The HE and GE values for ethyl iodide+toluene are positive throughout the ethyl iodide concentration range and GE>HE. The results have been analyzed in terms of Flory and ideal associated model theory of nonelectrolyte solutions. It has been observed that the ideal associated model approach which assumes the presence of AN and A2B molecular species describes well (within±10 J-mol–1 in the worst case) the general dependence of HE on XA (mole fraction of ethyl iodide) over the whole composition range for ethyl iodide+toluene mixtures. The equilibrium constants for A+A AB and 2A+BA2B reactions along with the enthalpies of formation of AB and A2B molecular species have been calculated. 相似文献
48.
CNDO MO calculations are carried out for four acrylates, H2C=C (R1)-COO (R2) with R1=H, Me and R2=Me, Et for dipole moment determination using the Pople-Segal expression.7 Energy minimization for various conformers in each molecular system was achieved by the gradient method. Dipole moments for comparatively stable conformers of each of the molecules considered are reported. Theoretically calculated energy values are used to arrive at the equilibrium geometry and the corresponding dipole moments are compared with the experimental values in each system considered. 相似文献
49.
Kulwant Singh Kawaldeep Vijay Kumar 《Journal of Radioanalytical and Nuclear Chemistry》1998,231(1-2):45-50
The sum peak at 437 keV (356+81 keV) has been measured in various chemical and physico-chemical environments. The fact that
the intensity ratio of the sum peak to its single peak changes with the circumstances in which the radioactive source is placed
is used to observe the effect of the chemical environment on directional correlation coefficients of 351–81 keV cascade in133Ba−133Cs decay and to detect the variations in the electric field gradient in different barium compounds. The sum peak method has
been found to be useful in describing the chemical influences onG
22 parameters and hence in the study of electric field gradients. 相似文献
50.
Summary Thermodynamic effective fixed charge densities of mercuric phosphate and carbonate parchment supported membranes were evaluated by a number of methods particularly those ofTeorell-Meyer-Sievers, Altug andHair andKobatake et al. The value of the permselectivity was obtained for the two membranes based onKobatake et al. procedure. Membrane transport number was calculated using a modified Nernst relation and compared with the values determined by the TMS method. The theoretical predictions for membrane potential usingKobatake et al. equation are borne out quite satisfactorily by our experimental results for both membrane.
With 8 figures and 3 tables 相似文献
Zusammenfassung Es wurden die Dichte der fixierten Ladungen von Quecksilberphosphat und Quecksilberkarbonat-Niederschlagsmembranen nach den Methoden vonTorell-Meyer-Sievers, Altug undHair undKobatake bestimmt. Weiterhin wurden Durchlässigkeit und Transportzahlen ermittelt und mit Werten der TMS-Methode verglichen. Theoretische Voraussagen über das Membranpotential nach den Gleichungen vonKobatake stimmen mit den experimentellen Ergebnissen überein.
With 8 figures and 3 tables 相似文献