STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: V. THE DECOMPOSITION OF PARACETALDEHYDE AT HIGH PRESSURES

1934 ◽  
Vol 11 (2) ◽  
pp. 180-189 ◽  
Author(s):  
A. L. Geddes ◽  
C. C. Coffin
Keyword(s):  
Liquid Phase ◽  
Critical Point ◽  
Vapor Phase ◽  
High Pressures ◽  
Heterogeneous Systems ◽  
Homogeneous Reaction ◽  
Reaction Velocity ◽  
First Order ◽  
Gas Reactions ◽  
Liquid Vapor

The homogeneous first order gaseous decomposition of paraldehyde to acetaldehyde has been studied at temperatures from 230 to 254 °C. up to pressures at which the liquid phase makes its appearance, i.e., 12 atm. at 230° and 18 atm. at 254 °C. Over-all velocity constants for the homogeneous reaction in the heterogeneous liquid-vapor system have been determined from these pressures up to the critical point. The data confirm results already published. It is found that in the purely gaseous system increase of pressure tends to diminish the reaction velocity. That the specific reaction velocity in the liquid phase is greater than that in the vapor phase is shown by the fact that the velocity constants of the heterogeneous systems increase progressively with the liquid-vapor ratio. Extrapolation to 100% of liquid gives velocity constants about five times as great as those characteristic of the vapor phase. Peculiarities in the behavior of the system at the critical point and preliminary measurements of the velocity of the trimolecular reverse reaction are described.

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: VII. THE DECOMPOSITION OF ETHYLIDENE DIBUTYRATE AND HEPTYLIDENE DIACETATE

1937 ◽  
Vol 15b (6) ◽  
pp. 247-253 ◽  
Author(s):  
C. C. Coffin ◽  
J. R. Dacey ◽  
N. A. D. Parlee
Keyword(s):  
Activation Energy ◽  
Homologous Series ◽  
Reaction Velocity ◽  
Vapor State ◽  
Specific Reaction ◽  
First Order ◽  
Gas Reactions

Ethylidene dibutyrate and heptylidene diacetate decompose in the vapor state at temperatures between 200° and 300 °C. to form an aldehyde and an anhydride. The reactions are homogeneous, unimolecular, and complete. The activation energy is the same as that previously found for other members of this homologous series. Ethylidene dibutyrate decomposes at the same rate as ethylidene diacetate, and thus provides further evidence that the specific reaction velocity is independent of the size of the anhydride radicals. Heptylidene diacetate decomposes at the same rate as butylidene diacetate. This indicates that after the aldehyde radical has attained a certain size (three or four carbon atoms) the addition of –CH2− groups leaves the specific reaction velocity unchanged. The velocity constants are given by the equations[Formula: see text]

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: XI. THE DECOMPOSITION OF BENZYLIDENE DIACETATE, o-CHLOROBENZYLIDENE DIACETATE AND BENZYLIDENE DIBUTYRATE

1940 ◽  
Vol 18b (8) ◽  
pp. 223-230 ◽  
Author(s):  
N. A. D. Parlee ◽  
J. C. Arnell ◽  
C. C. Coffin
Keyword(s):  
Double Bond ◽  
Steric Factor ◽  
Reverse Reaction ◽  
Breaking Point ◽  
Reaction Velocity ◽  
First Order ◽  
Gas Reactions

Benzylidene diacetate, o-chlorobenzylidene diacetate, and benzylidene dibutyrate decompose unimolecularly at rates given by the equation previously found for crotonylidene diacetate and furfurylidene diacetate, viz., [Formula: see text]. The fact that these esters all have a double bond at the same distance from the breaking point of the molecule is considered significant in connection with their identical reaction velocity, which is about six times that of ethylidene diacetate. Benzylidene diacetate decomposes at the same rate in both the liquid and vapour states to reach an equilibrium given by the equation [Formula: see text]. The reverse reaction with a rate given by [Formula: see text] is characterized by a steric factor of 10−4.

scholarly journals The thermal decomposition of acetaldehyde and the existence of different activated states

1933 ◽  
Vol 141 (843) ◽  
pp. 41-55 ◽  
Keyword(s):  
High Pressures ◽  
Initial Pressure ◽  
Bimolecular Reaction ◽  
Bimolecular Reactions ◽  
First Order ◽  
Straight Line ◽  
Gas Reactions ◽  
Pass Through ◽  
Low Pressures ◽  
Kinetics Of

Homogeneous thermal gas reactions were at one time tacitly assumed to possess a definite order, unimolecular and bimolecular reactions, for example, being sharply distinguished. The kinetics of the decomposition of acetalde­ hyde, CH 3 CHO = CH 4 + CO, over the pressure range of 100 to 400 mm. were found to satisfy the criterion of a bimolecular reaction, namely, that the reciprocal of the time for half change (1/ t 1/2 ) )plotted against the initial pressure ( p 0 ) gave a straight line inclined to the axes. The line, however, did not pass through the origin, as may be seen in fig. 1 of the present paper. This indicated the presence of some first order reaction, the nature of which was not determined. Subsequently, in accordance with the collision theory of activation and deactivation, it was shown that certain reactions, sometimes called quasiummolecular, change their order from the second at low pressures to the first at high pressures. This apparently was the reverse of the behaviour shown by acetaldehyde.

STUDIES ON HOMOGENEOUS FIRST ORDER GAS REACTIONS: VIII. THE DECOMPOSITION OF TRICHLORETHYLIDENE DIACETATE AND TRICHLORETHYLIDENE DIBUTYRATE

1937 ◽  
Vol 15b (6) ◽  
pp. 254-259 ◽  
Author(s):  
N. A. D. Parlee ◽  
J. R. Dacey ◽  
C. C. Coffin
Keyword(s):  
Activation Energy ◽  
Experimental Error ◽  
Acid Anhydride ◽  
Exchange Energy ◽  
Reaction Velocity ◽  
First Order ◽  
Measurable Rate ◽  
Gas Reactions

Trichlorethylidene diacetate and trichlorethylidene dibutyrate have been found to decompose at temperatures between 200° and 290 °C. at a measurable rate to give chloral and an acid anhydride. The reactions are homogeneous and of the first order, and have the same specific velocity in both the liquid and vapor states. The activation energy is identical (within experimental error) with that previously found for non-chlorinated members of this series of esters. The two compounds decompose at the same rate, in agreement with the hypothesis that the anhydride radicals do not easily exchange energy with the bonds that break. This reaction velocity, which is somewhat smaller than that of ethylidene diacetate at any temperature, is given by the equation [Formula: see text].

First-order liquid-liquid phase transition in compressed hydrogen and critical point

2019 ◽  
Vol 150 (20) ◽  
pp. 204114 ◽  
Author(s):  
Chunling Tian ◽  
Fusheng Liu ◽  
Hongkuan Yuan ◽  
Hong Chen ◽  
Anlong Kuan
Keyword(s):  
Phase Transition ◽  
Liquid Phase ◽  
Critical Point ◽  
Liquid Phase Transition ◽  
First Order

scholarly journals Water liquid-vapor equilibrium by molecular dynamics: Alternative equilibrium pressure estimation

2016 ◽  
Vol 9 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Michal Ilčin ◽  
Martin Michalík ◽  
Klára Kováčiková ◽  
Lenka Káziková ◽  
Vladimír Lukeš
Keyword(s):  
Molecular Dynamics ◽  
Liquid Phase ◽  
Vapor Phase ◽  
Border Effect ◽  
Simple Method ◽  
Equilibrium Pressure ◽  
Vapor Equilibrium ◽  
Vaporization Heat ◽  
Pressure Estimation ◽  
Liquid Vapor

Abstract The molecular dynamics simulations of the liquid-vapor equilibrium of water including both water phases — liquid and vapor — in one simulation are presented. Such approach is preferred if equilibrium curve data are to be collected instead of the two distinct simulations for each phase separately. Then the liquid phase is not restricted, e.g. by insufficient volume resulting in too high pressures, and can spread into its natural volume ruled by chosen force field and by the contact with vapor phase as vaporized molecules are colliding with phase interface. Averaged strongly fluctuating virial pressure values gave untrustworthy or even unreal results, so need for an alternative method arisen. The idea was inspired with the presence of vapor phase and by previous experiences in gaseous phase simulations with small fluctuations of pressure, almost matching the ideal gas value. In presented simulations, the first idea how to calculate pressure only from the vapor phase part of simulation box were applied. This resulted into very simple method based only on averaging molecules count in the vapor phase subspace of known volume. Such simple approach provided more reliable pressure estimation than statistical output of the simulation program. Contrary, also drawbacks are present in longer initial thermostatization time or more laborious estimation of the vaporization heat. What more, such heat of vaporization suffers with border effect inaccuracy slowly decreasing with the thickness of liquid phase. For more efficient and more accurate vaporization heat estimation the two distinct simulations for each phase separately should be preferred.

scholarly journals Scaling of Phase Diagram and Critical Point Parameters in Liquid-Vapour Phase Transition of Metallic Fluids

2020 ◽  
Author(s):  
S.V.G. Menon
Keyword(s):  
Phase Transition ◽  
Critical Point ◽  
Phase Diagrams ◽  
Vapor Phase ◽  
Cohesive Energy ◽  
Coupling Parameter ◽  
Thermodynamic Quantities ◽  
Parameter Expansion ◽  
Scaling Variables ◽  
Liquid Vapor

The first objective of this paper is to investigate the scaling behavior of liquid-vapor phase transition in FCC and BCC metals starting from the zero-temperature four-parameter formula for cohesive energy. The effective potentials between the atoms in the solid are determined using lattice inversion techniques as a function of scaling variables in the above formula. These potentials are split into repulsive and attractive parts as per the Weeks-Chandler-Anderson prescription, and used in the coupling-parameter expansion for solving the Ornstein-Zernike equation supplemented with an accurate closure. Thermodynamic quantities obtained via the correlation functions are used to obtain critical point parameters and liquid-vapor phase diagrams. Their dependence on the scaling variables in the cohesive energy formula are also determined. Equally important second objective of the paper is to revisit coupling parameter expansion for solving the Ornstein-Zernike equation. The Newton-Armijo non-linear solver and Krylov-space based linear solvers are employed in this regard. These methods generate a robust algorithm that can be used to span the entire fluid region, except very low temperatures. Accuracy of the method is established by comparing the phase diagrams with those obtained via computer simulation. Avoidance of the 'no-solution-region' of Ornstein-Zernike equation in coupling-parameter expansion is also discussed. Details of the method and the complete algorithm provided here would make this technique more accessible to researchers investigating thermodynamic properties of one component fluids.

scholarly journals Scaling of Phase Diagram and Critical Point Parameters in Liquid-Vapour Phase Transition of Metallic Fluids

2021 ◽  
Vol 6 (1) ◽  
pp. 6
Author(s):  
S.V.G. Menon
Keyword(s):  
Phase Transition ◽  
Critical Point ◽  
Phase Diagrams ◽  
Vapor Phase ◽  
Cohesive Energy ◽  
Coupling Parameter ◽  
Thermodynamic Quantities ◽  
Parameter Expansion ◽  
Scaling Variables ◽  
Liquid Vapor

The first objective of this paper is to investigate the scaling behavior of liquid-vapor phase transition in FCC and BCCmetals starting from the zero-temperature four-parameter formula for cohesive energy. The effective potentials between the atoms in the solid are determined while using lattice inversion techniques as a function of scaling variables in the four-parameter formula. These potentials are split into repulsive and attractive parts, as per the Weeks–Chandler–Anderson prescription, and used in the coupling-parameter expansion for solving the Ornstein–Zernike equation that was supplemented with an accurate closure. Thermodynamic quantities obtained via the correlation functions are used in order to obtain critical point parameters and liquid-vapor phase diagrams. Their dependence on the scaling variables in the cohesive energy formula are also determined. An equally important second objective of the paper is to revisit coupling parameter expansion for solving the Ornstein–Zernike equation. The Newton–Armijo non-linear solver and Krylov-space based linear solvers are employed in this regard. These methods generate a robust algorithm that can be used to span the entire fluid region, except very low temperatures. The accuracy of the method is established by comparing the phase diagrams with those that were obtained via computer simulation. The avoidance of the ’no-solution-region’ of the Ornstein-Zernike equation in coupling-parameter expansion is also discussed. Details of the method and complete algorithm provided here would make this technique more accessible to researchers investigating the thermodynamic properties of one component fluids.

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