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1.
N. Binke L. Rong Y. Zhengquan W. Yuan Y. Pu Hu Rongzu Y. Qingsen 《Journal of Thermal Analysis and Calorimetry》1999,58(2):403-411
The kinetics of the first order autocatalytic decomposition reaction of highly nitrated nitrocellulose (HNNC, 14.14%N) was studied by using thermogravimetry (TG). The results show that the TG curve for the initial 50% of mass-loss of HNNC can be described by the first order autocatalytic equation
and that for the latter 50% mass-loss of HNNC described by the reaction equations
and
This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
2.
C Paz-Ramos C A Cerdeiriña J Troncoso L Romaní 《Journal of Thermal Analysis and Calorimetry》2006,83(2):263-268
In the search of a useful
method for determining excess enthalpies as a function of temperature Calvet
calorimetry was employed. To this end, excess molar enthalpies
at 298.15 and 333.15 K and excess molar heat capacities
within 283.15–333.15 K were
determined for the 1-decanol+n-decane system
over the whole composition range. An isothermal flow Calvet-type calorimeter
was used for
measurements, whereas
were determined by means of a Setaram
Micro DSC calorimeter. Excess enthalpies within 283.15–333.15 K were
indirectly obtained through the integration of
(T) data using
at 298.15 K. The results obtained at 333.15 K agreed with those
determined directly, implying the thermodynamic consistency of the measured
data and, therefore, the reliability of the indirect method. 相似文献
3.
Minewaki K. Kato T. Yoshida H. Imai M. 《Journal of Thermal Analysis and Calorimetry》1999,57(3):753-758
We have investigated effects of shear flow on the structure of lamellar phase in hepta(oxyethylene glycol)—n—hexadecylether—water system using small-angle neutron scattering (SANS) under shear flow at the shear rates (
) from 10–3 s–1 to 50 s–1. In the range
=10–2 ~1 s–1, significant changes have been observed in both intensity and position of the reflection peak. Small-angle X-ray scattering without shear has been also measured at various concentrations and temperatures. It has been suggested from these results that the shear flow causes contraction of lamellar domains and formation of a new domain composed of disrupted bilayers which grows rapidly with increasing shear rate and reconstructs original microstructures.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
4.
Enthalpic relaxation has been used to model the development of the glass transition in polymers, using kinetic parameters
determined separately. For this purpose the Kohlrausch-Williams-Watt stretched exponential function, relating the extent of
relaxation, Φ(t), to time t and an average relaxation time, τa, i.e.
where β is inversely related to the breadth of the relaxation spectrum, has been adopted. The relaxation time dependence
on temperature was taken to follow the modified Arrhenius relationship,
where T is the storage and T′ the fictive temperature, X is the structure factor and ΔH the activation enthalpy. Both have
been found to describe the process of enthalpic relaxation in polymer glasses and a direct comparison has been made with the
change in specific heat observed with different cooling rates in DSC experiments. The effect of variables, such as activation
enthalpies, pre-exponential factors, and the non-linear factors such as X and β on the observed Tgs and the temperature range over which the transition occurred have been determined.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
The Pitzer model is applied to simulate various single- and multistage modifications of the industrial conversion process
by repetitive thermochemical equilibrium calculations. In this work, good agreement between simulated values and operating data was found because the Pitzer model accurately predicts the solubility of the various salts involved in different stages of the process operating from 0 to 120°C. 相似文献
6.
The solubility of siderite (FeCO3) at 25°C under constant CO2 partial pressure [p(CO2)] was determined in NaCl solutions as a function of ionic strength. The dissolution of FeCO3(s) for the reaction
has been determined as a function of pH = – log[H+]. From these values we have determined the equilibrium constant for the stoichiometric solubility to FeCO3(s) in NaCl
These values have been fitted to the equation
with a standard error of s = 0.15. The extrapolated value of log(K
o
sp) – 10.9 in water is in good agreement with data in the literature (– 10.8 to – 11.2) determined in solutions of different composition and ionic strength.The measured values of the activity coefficient, T(Fe2+) T(CO3
2–), have been used to estimate the stability constant for the formation of the FeCO3 ion pair, K*(FeCO3). The values of K*(FeCO3) have been fitted to the equation (s = 0.09)
The value of log[K
o(FeCO3)] in water found in this study (6.3 ± 0.2) is slightly higher than the value found from extrapolations in 1.0 m NaClO4 solutions (5.9 ± 0.2). These differences are related to the model used to determine the activity coefficients of the Fe(II) and carbonate species in the two solutions. 相似文献
7.
The equilibrium constant for the hydrolytic disproportionation of I2
has been determined at 25°C and at ionic strength 0.2 M(NaClO4) in buffered solution. The reaction was followed in the pH range where the equilibrium concentration of I2, I–, and IO3
–are commensurable, i.e., the fast equilibrium
is also established. The equilibrium concentrations of I2and I3
–were determined spectrophotometrically, and the concentrations of all the other species participating in process (1) were calculated from the stoichiometric constraints. The constants determined are \log K_1 = -47.61\pm 0.07 and \log K_2 = 2.86 \pm 0.01. 相似文献
8.
The example of the sequence of reactions
and the steady-state approximation are used to present a demonstration of the fact that the evolution of the reaction rates
under non-isothermal conditions depends on the ratio of the activation energies and on the heating rate. At the same time,
it is shown that, under isothermal conditions, the ratio of the activation energies plays no role.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
9.
Dubey Sapna Sharma Neetu Khandelwal Chandra L. Sharma Prem D. 《Transition Metal Chemistry》2003,28(2):176-181
The kinetics of osmium(VIII)-catalyzed oxidation of hypophosphite with hexacyanoferrate(III) in alkaline medium has been studied. The rate is independent of the concentration of the oxidant. The order with respect to hydroxide ion is variable. Rate law (1) conforms with the experimental observations.
The equilibrium constant 'K
1' for step (2)
has been evaluated kinetically to be (21 ± 5.0), (23 ± 5.0), (26 ± 6) and (32 ± 6) at 25, 30, 32 and 35 °C and I = 1.0 mol dm–3 respectively. The energy and entropy of activation were calculated to be (42 ± 2.0) kJ mol–1 and (82 ± 6.0) J K–1 mol–1 respectively. A plausible reaction mechanism has been suggested. 相似文献
10.
11.
The solubility of rhodochrosite (MnCO3) at 25°C under constant carbon dioxide partial pressure p(CO2) was determined in NaCl solutions as a function of ionic strength I. The dissolution of MnCO3(s) for the reaction
has been determined as a function of pH. From these values, we have determined the equilibrium constant for the stoichiometric solubility of MnCO3(s) in NaCl solutions
These values have been fitted to the equation
with a standard error of = 0.1 with Iand concentrations in molalities. The extrapolated value of log K
o
sp(–10.3) in water is in good agreement with literature data (–10.1 to 10.8) determined in solutions of different composition and ionic strength. The measured values of the activity coefficient, T(Mn2+) and T(CO3
2–), have been used to estimate the stability constant for the formation of the MnCO3ion pair, K
*(MnCO3
0). The value of K
0(MnCO3
0) calculated from the values of K
*(MnCO3) by the Pitzer equation ( = 0.1) in this study (4.8 ± 0.1) is in reasonable agreement with literature data. 相似文献
12.
A new approximation is proposed to the integral of the Boltzmann factor:
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相似文献
13.
Khan Zaheer Rafiquee Mohammad Z. A. Niaz Mohammad A. Khan Abdul Aziz Kabir-ud-Din 《Transition Metal Chemistry》1998,23(5):537-540
The kinetics of alkaline hydrolysis of Co(Asn)2, yielding Co(OH)2, NH3 and aspartic acid, have been studied spectrophotometrically, and the effects of CoII and NaOH concentrations on the reaction rate determined. The rate increases with increasing [NaOH], whereas variation of [CoII] has no significant effect. The kinetics of NH3 evolution conform to the rate law:
14.
Rosso Janina A. Villata Laura S. Mártire Daniel O. Capparelli Alberto L. 《Transition Metal Chemistry》1998,23(5):645-648
The molecular oxygen-mediated decomposition of the binuclear complex, prepared from oxomolybdate(V) and L-(+)-cysteine, was studied spectrophotometrically at pH 3.5–5.6. The formation of MoVI was detected. The effects of pH and [O2] on the decomposition kinetics are given by the equation:
15.
The thermal decomposition of zirconium oxyhydroxides prepared by the mixture of aqueous zirconium oxychloride solutions and aqueous solutions of sodium hydroxide or ammonium hydroxide under various conditions has been examined by thermogravimetry, differential thermal analysis, X-ray diffraction study and infrared spectrophotometry. As a result, it is seen that the thermal decomposition of zirconium oxyhydroxide, in which the composition is ZrO2-x(OH)2xyH2O where x2 and 1y<2, proceeds according to the following process:
16.
Jia-Zhen Yang Dian-Zhen Lu Hong-Chang Li Chao-Jun Hou 《Journal of solution chemistry》2003,32(6):559-567
The determination of the second dissociation constant of carbonic acid K
2 in 5, 15, and 25 mass% ethanol—water mixed solvents has been made using cell of the type:
17.
Conditional stability constants of 2-[bis(2-hydroxyethyl)amino]-2(hydroxymethyl)-1,3-propanediol (BT) complexes of trivalent rare earth element (Ln) ions (La, Nd, Eu, Gd, Yb, Dy, Er, Lu) and Y were determined potentiometrically in aqueous NaCl solutions at 30°C and 0.1 M ionic strength. Least-squares fitting shows that, at <0.04 molal BT, the complex LnBT3+ is dominant, with LnBT2
3+ forming a secondary complex, where:
18.
Solubility of Oxygen in Some 1-1, 2-1, 1-2, and 2-2 Electrolytes as a Function of Concentration at 25°C 总被引：1，自引：0，他引：1
The solubility of oxygen has been measured in a number of electrolytes [(LiCl, KCl, RbCl, CsCl, NaF, NaBr, NaI, NaNO3, KBr, KI, KNO3, CaCl2, SrCl2, BaCl2, Li2SO4, K2SO4, Mn(NO3)3)] as a function of concentration at 25°C. The solubilities, mol (kg-H2O)–1, have been fitted to a function of the molality m (standard deviation < 3mol-kg–1)
19.
Zhengping Hao Lidun An Hongli Wang Tiandou Hu 《Reaction Kinetics and Catalysis Letters》2000,70(1):153-160
Based on the structure of characterization of Au/Fe2O3 catalysts, the mechanism of gold activation in supported gold catalysts was proposed as follow:
20.
Z. Xiancheng N. Zhaodong X. Yan Z. Yuanqin Z. Honglin 《Journal of Thermal Analysis and Calorimetry》1999,58(2):279-285
The power-time curves of two species of bacteria, Vibro metschnikovii, Vibro bollisae were determined calorimetrically by using a 2277 bioactivity monitor. The power-time curve equation of bacterial growth in the log phase can be expressed as
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