THE INFRARED SPECTRUM AND THERMAL DECOMPOSITION OF HYDRAZINE PERCHLORATE HEMIHYDRATE

1966 ◽  
Vol 44 (20) ◽  
pp. 2435-2443 ◽  
Author(s):  
P. W. M. Jacobs ◽  
A. Russell-Jones
Keyword(s):  
Infrared Spectrum ◽  
Reaction Mechanisms ◽  
Low Temperatures ◽  
Room Temperature ◽  
Kcal Mole ◽  
Absorption Bands ◽  
Kinetics Of Decomposition ◽  
Salt Melts ◽  
Chemical Equation ◽  
Kinetics Of

The infrared spectrum of hydrazine perchlorate hemihydrate (HPH) has been determined and an assignment of the absorption bands made. Invacuo, HPH will partially dehydrate even at room temperature; when heated the remainder of the half-mole of water is lost at 61 °C. The dehydrated salt melts at 138 °C and decomposition ensues. The kinetics of decomposition may be followed in the temperature range 180–280 °C. The activation energy is 36.3 kcal/mole. At low temperatures the decomposition is represented by the chemical equation[Formula: see text]but when the temperature is high enough the rate of decomposition of the ammonium perchlorate formed becomes appreciable also. Possible reaction mechanisms are discussed.

The photochemical and thermal decompositions of hydrogen sulphide

1953 ◽  
Vol 216 (1126) ◽  
pp. 344-361 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Quantum Yield ◽  
Hydrogen Sulphide ◽  
Low Temperatures ◽  
Room Temperature ◽  
Large Fraction ◽  
Kcal Mole ◽  
Hydrogen Atoms ◽  
Photochemical Decomposition ◽  
Bimolecular Mechanism

The photochemical decomposition of hydrogen sulphide has been investigated at pressures between 8 and 550 mm of mercury and at temperatures between 27 and 650° C, using the narrow cadmium line ( λ 2288) and the broad mercury band (about λ 2550). At room temperature the quantum yield increases with pressure from 1.09 at 30 mm to 1.26 at 200 mm. Above 200 mm pressure there was no further increase in the quantum yield. Temperature had little effect on the quantum yield at λ 2550, but there was a marked increase in the rate of hydrogen production between 500 and 650° C with 2288 Å radiation. This may have been caused by the decomposition of excited hydrosulphide radicals. The results are consistent with a mechanism involving hydrogen atoms and hydrosulphide radicals. The mercury-photosensitized reaction is less efficient than the photochemical decomposition, the quantum yield being only about 0.45. The efficiency increased with temperature and approached unity at high temperatures and pressures. This agrees with the suggestion that a large fraction of the quenching collisions lead to the formation of Hg ( 3 P 0 ) atoms. The thermal decomposition is heterogeneous at low temperatures and becomes homogeneous and of the second order at 650° C. The experimental evidence suggests the bimolecular mechanism 2H 2 S → 2H 2 + S 2 . The activation energies are 25 kcal/mole (heterogeneous) and 50 kcal/mole (homogeneous).

Variation of sticking probabilities with temperature and coverage, and desorption spectra for nitrogen on tungsten films

1967 ◽  
Vol 297 (1450) ◽  
pp. 321-335 ◽  
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Continuous Distribution ◽  
Kcal Mole ◽  
Initial Value ◽  
Precursor State ◽  
Heats Of Adsorption ◽  
Sticking Probabilities ◽  
Increasing Temperature ◽  
Pressure Changes

From 78 to 150°K, and at coverages < 8 x 10 14 molecules/cm 2 , the sticking probability s of nitrogen on tungsten films (= 0·9) is independent of both temperature and coverage, whereas at temperatures above 150°K it is a function of both these variables. These results are interpreted in terms of a physically adsorbed precursor state with a heat of adsorption of ca . 3 kcal/mole. It is concluded that only a fraction of molecules colliding with the surface enter this state and that it is this fraction which determines the initial value of s at low temperatures. The decrease of s with increasing temperature above 150°K is a consequence of the inactivity of some planes, such as the (110), at the higher temperatures. Desorption spectra were obtained by warming films from 78°K to room temperature and recording the subsequent pressure changes as a function of time. From these data the distribution of site energies for the weakly held adsorbate (the αγ state) was evaluated, indicating a continuous distribution with heats of adsorption varying between 6 and 20 kcal/mole.

MOLECULAR REORIENTATION IN FERROELECTRIC LITHIUM HYDRAZINIUM SULPHATE

1967 ◽  
Vol 45 (10) ◽  
pp. 3257-3263 ◽  
Author(s):  
W. D. MacClement ◽  
M. Pintar ◽  
H. E. Petch
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Resonance Absorption ◽  
Spin Lattice Relaxation ◽  
Kcal Mole ◽  
Molecular Reorientation ◽  
Hindered Rotation ◽  
Spin Lattice

The temperature dependence of the spin-lattice relaxation time T1 and of the second moment of the magnetic-resonance absorption signal has been determined for protons in powdered lithium hydrazinium sulphate over the range 80–480 °K. These measurements indicate that the hydrazinium ion is rigid only at very low temperatures. As the temperature is raised, the −NH3 group begins to undergo hindered rotation about the N–N axis with an activation energy of 4.2 kcal/mole and the effect of this motion on the line width becomes pronounced in the region of 85 °K. Further molecular reorientation begins above room temperature and is probably reorientation of the −NH2 group about either the N–N axis or the bisectrix of the H–N–H angle. Above 435 °K the hydrazinium ion begins to tumble about several axes and at 480 °K diffuses through the structure.

Synthesis and kinetics of decomposition of some novel S-nitrosothiols

1999 ◽  
Vol 77 (5-6) ◽  
pp. 550-556 ◽  
Author(s):  
Andrew P Munro ◽  
D Lyn H. Williams
Keyword(s):  
Nitric Oxide ◽  
Room Temperature ◽  
Alternative Pathway ◽  
Copper Catalysis ◽  
Induction Periods ◽  
Kinetics Of Decomposition ◽  
Initial Generation ◽  
Kinetics Of ◽  
Reaction Schemes

TheS-nitrosothiols 2-acetamido-2-deoxy-S-nitroso-1-thio-β-D-glucopyranose 3,4,6-triacetate (GPSNO) and S-nitroso-N-carbamyl-D,L-penicillamine (SNCP) were synthesized by S-nitrosation of the corresponding thiols, isolated, and fully characterized. The nitrosothiol (TGSNO) from 1-thioglycerol was obtained as a red gelatinous liquid, which decomposed rapidly at room temperature and so was not characterized. The kinetics of decomposition of GPSNO showed that there is a surprisingly large thermal pathway overlaid with a Cu2+/RS- catalyzed reaction. The results strongly suggest that the product disulfide complexes Cu2+ (for which there is some spectral evidence), leading to incomplete conversion by that route. Ascorbate also acts as a Cu2+ reductant. Another S-nitroso sugar, S-nitroso-1-thio-β-D-glucose (SNTG), behaved very similarly from solutions generated and used in situ. The decomposition of TGSNO shows induction periods suggesting that slow initial generation of Cu+ (the true catalyst) is taking place. There appears to be also a significant alternative pathway (analogous to that found for GPSNO), where the rate appears to be independent of [Cu2+], but very unusually this pathway is effectively halted by addition of EDTA either at the start of the reaction or at a later time. Reaction schemes are put forward to account for these unusual reaction characteristics.Key words: S-nitrosothiols, nitric oxide, ascorbate, copper catalysis.

Fast kinetics of Mg2+/Li+ hybrid ions in a polyanion Li3V2(PO4)3 cathode in a wide temperature range

2019 ◽  
Vol 7 (16) ◽  
pp. 9968-9976 ◽  
Author(s):  
Muhammad Rashad ◽  
Hongzhang Zhang ◽  
Xianfeng Li ◽  
Huamin Zhang
Keyword(s):  
Wide Temperature Range ◽  
Low Temperatures ◽  
Room Temperature ◽  
Excellent Performance ◽  
Fast Kinetics ◽  
Temperature Range ◽  
Kinetics Of

A Li3V2(PO4)3 based Mg2+/Li+ hybrid battery with excellent performance both at room temperature and low temperatures (0, −10, −20, −30, and −40 °C) is presented.

A shock-tube study of the kinetics of decomposition of sulphur dioxide

1963 ◽  
Vol 276 (1367) ◽  
pp. 461-474 ◽  
Keyword(s):  
Activation Energy ◽  
Triplet State ◽  
Sulphur Dioxide ◽  
Direct Reaction ◽  
Kcal Mole ◽  
Absorption Bands ◽  
True Activation Energy ◽  
Rate Of Increase ◽  
Reaction Theory ◽  
Kinetics Of

The rate of increase in strength of absorption bands of SO has been measured in shock-heated mixtures of sulphur dioxide and argon. Arrhenius-type plots indicate a unimolecular first step of the order d [SO]/d t = k [SO 2 ] [ M ], where [SO], [SO 2 ] and [ M ] are concentrations of [SO], [SO 2 ] and total gas. The apparent activation energy at around 3500 °K is 56 kcal/mole. It is shown that on unimolecular reaction theory, if four harmonic modes of oscillation in the SO 2 molecules contribute to the energy available for transformation, the true activation energy is 74 kcal/mole. This agrees with the energy of excitation to a known triplet state of SO 2 , and on this basis it is suggested that the first steps in the decomposition are SO 2 + M = SO* 2 + M — 73.6 kcal/mole (1) and SO* 2 + SO 2 = SO 3 + SO + 25.6 kcal/mole. (2) Step (2) is spin-allowed, whereas the more direct reaction SO 2 + SO 2 = SO 3 + SO —48 kcal/ mole is spin-forbidden. This is an unusual type of decomposition mechanism and occurs because of the high dissociation energy of SO 2 , because the direct step of low-energy is spinforbidden, and because there is a favourably situated triplet state of the molecule.

scholarly journals MICROSPECTROPHOTOMETRY OF CYTOCHROMES IN THE SINGLE CELL AT ROOM AND LIQUID NITROGEN TEMPERATURES

1965 ◽  
Vol 26 (3) ◽  
pp. 741-746 ◽  
Author(s):  
B. Thorell ◽  
B. Chance ◽  
V. Legallais
Keyword(s):  
Low Temperature ◽  
Single Cell ◽  
Liquid Nitrogen ◽  
Low Temperatures ◽  
Room Temperature ◽  
Single Cells ◽  
Visible Region ◽  
Absorption Bands ◽  
Preliminary Results ◽  
Favorable Conditions

By increasing further the sensitivity of microspectrophotometry, it is now possible to measure, under favorable conditions, the smaller absorption bands of the respiratory pigments of single cells in the visible region of the spectrum. A considerable aid in the distinction between cytochromes is afforded by liquid nitrogen microspectrophotometry. Under favorable conditions, the height of the peaks is increased over 8-fold at low temperatures. In diploid yeast, characteristically sharpened components not resolvable at room temperature are observed at low temperature; and in pentaploid yeast, a hitherto unrecognized pigment is observed at 583 mµ. These preliminary results indicate the feasibility and the value of low temperature microspectrophotometry of biological materials.

Kinetics of Decomposition of Titanium Tetraiodide

1963 ◽  
Vol 16 (1) ◽  
pp. 66
Author(s):  
KM Bowling
Keyword(s):  
Gas Phase ◽  
Electrical Conductance ◽  
Phase Reaction ◽  
Kcal Mole ◽  
Gas Phase Reaction ◽  
First Order ◽  
Kinetics Of Decomposition ◽  
Vapour Concentration ◽  
Counter Current ◽  
Kinetics Of

����� The rate of growth of an incandescent filament exposed to a steady stream of titanium tetraiodide vapour was determined from changes in the electrical conductance of the filament, and used to calculate the rate of decomposition of titanium tetraiodide at 1100-1500�C and at various vapour pressures. The method used eliminates the effects of titanium evaporation, counter-current gaseous diffusion, and the iodide synthesis reaction, which have influenced previous work.�The results show that the rate of decomposition is proportional to the vapour concentration but independent of the surface area for a given length of filament. The decomposition rate varies with temperature according to an Arrhenius-type relationship, leading to a provisional estimate for the energy of activation of 28.6 kcal/mole. Under suitable conditions high deposition rates are obtained. The decomposition appears to proceed as a first-order, homogeneous, gas-phase reaction in a hot reaction zone around the filament, rather than heterogeneously on the surface.

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