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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.
Z. L. Zhang M. H. Zhong J. Liu F. M. Liu Z. Z. Wang F. P. Zhong F. Wu 《Journal of Thermal Analysis and Calorimetry》1999,58(2):421-433
In this work some calorimetric measurements were also carried out on the electrorefining silver by using different current densities with a Calvet type microcalorimeter at room temperature. The ratio (R) of the measured heat (
m) to the input electric energy (
in) and the excess heat (
ex), i.e., difference between
m and
in during the electrorefining process, were discussed in terms of general thermodynamics. It was found that the R and
ex for silver were related with the current density or cell voltage employed in the experiment. The results obtained here also indicate that the heat generation under different conditions, such as different currents or voltages may be caused partially by the irreversibility of the process or by some unknown processes.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
4.
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
5.
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
. A self-function recursion equation, fi=b1fi+1+b2fi+2, was obtained through the perfect non-linear function
. A linear equation, i/i+1=b1+b2i+2/i+1, was obtained by using the self-function recursion equation. The rate constants of bacterial growth k1, the time constant of the calorimeter k, the generation times G, and the pre-exponential factors A were obtained from the power—time curve equations.Power—time curve equations of bacterial growth in the log phase are expressed for V.metschnikovii as =1.05(e0.0228t–e–0.0175t), and for V. bollisae as =1.58(e0.0278t–e–0.0170t).This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
6.
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
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.
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
9.
H. R. Galleguillos-Castro F. Hernández-Luis L. Fernández-Mérida M.A. Esteso 《Journal of solution chemistry》1999,28(6):791-807
Activity coefficients for sodium chloride in the NaCl + Na2SO4 + H2O ternary system were determined from emf measurements of the cell
at 15, 25, 35, and 45°C and at total ionic strengths from 0.1 to 6 mol-kg–1. These activity coefficient were analyzed by using the Harned rule and the treatments of Scatchard–Rush–Johnson and Pitzer. The analysis of activity coefficients at trace concentration was also achieved and qualitatively interpreted by considering the ionic interactions that can take place in the mixed system. Finally, the excess Gibbs energy of the mixtures was calculated and qualitatively analyzed against the composition of the system. 相似文献
10.
The Apparent Molal Volume and Compressibility of Seawater Fit to the Pitzer Equations 总被引：1，自引：0，他引：1
The density and compressibility of seawater salt solutions for ionic strengths 0to 0.8 m, temperatures 0–40°C, and applied pressure 0 to 1000 barare fitted tothe Pitzer equations. The apparent molal volumes and compressibilities (X) arefitted to equations of the form
where I is the ionic strength, m is the molality of seasalt, A
X is the Debye—Hückelslope for the volume (X = V) or compressibility(X = ) and g(y) = (2/y
2)[1 – (1 + y)exp(x)] where y = 2I
0.5. The Pitzer parameters (0)X,(1)X, and C
Xare fitted to functions of temperature and pressure in the form
where a
ij are adjustable parameters, Y
X is the Pitzer parameter, T is the temperaturein K, T
R = 298.15 K, and P is the applied pressure in bars (P = 0 at 1 atm or1.013 bar). The standard deviations of the seawater fits are 8.3×10–6 cm3-g–1for the specific volumes, 0.0007×10–6 bar–1 for the compressibilities, and0.63×10–6 K–1 for the thermal expansibilities. At 25°C, the measured densitiesof seawater are compared to the calculated values using Pitzer coefficients forthe major sea salts. The results agree with the measured values to within 45×10–6g-cm–3. 相似文献
11.
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
12.
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:
It is proposed that the reaction proceeds through formation of a dianionic tetrahedral intermediate. 相似文献
13.
A new approximation is proposed to the integral of the Boltzmann factor:
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相似文献
14.
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:
15.
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:
16.
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.
17.
The kinetics and mechanism of chromium(VI) oxidation of L-methionine in acidic medium have been studied spectrophotometrically. The reaction proceeds via the formation of a transient intermediate (max = 410–420 nm) which decomposes by a proton catalyzed pathway. The rate law is:
18.
Virender K. Sharma Fabien Casteran Frank J. Millero Concetta De Stefano 《Journal of solution chemistry》2002,31(10):783-792
The sulfur-containing biomolecule, cysteine has a role in physiological and natural environment because of its strong interactions with metals. To understand these interactions of metals with cysteine, one needs reliable dissociation constants for the protonated cysteine species [
CH(CH2SH)COOH; H3B+]. The values of dissociated constants, p
, for protonated cysteine species (H3B+ H+ + H2B, K
1; H2B H+ + HB–,K
2; HB– H+ + B2–,K
3) were determined from potentiometric measurements in NaCl solutions as a function of ionic strength, 0.5–6.0 mol-(kgH2O)–1 and between 5, and 45°C. The equations
19.
Compensation effect as a consequence of vibrational energy transfer in homogeneous and isotropic heat field 总被引：1，自引：1，他引：0
Nicolina Pop Gabriela Vlase T. Vlase N. Doca A. Mogoş A. Ioiţescu 《Journal of Thermal Analysis and Calorimetry》2008,92(1):313-317
By kinetics of decomposition of solids in both isothermal and non-isothermal conditions, the compensation effect (CE) is rather
a rule.
The topic of this work is to suggest an activation mechanism which leads to the dependences similar with CE.
The solid is assimilated to a system of the harmonic oscillator with a Bose-Einstein energy distribution.
Considering an activation process due to a vibrational energy transfer from a homogeneous and isotropic field of thermic oscillators
to the solid-state oscillator, the thermodynamic functions are in the relationship
20.
The Pitzer model is applied to simulate various single- and multistage modifications of the industrial conversion process
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