Wyniki wyszukiwania - Biblioteka Nauki

1

Thermodynamics of a 3 - D charged rotating hairy black hole

100%

Naji J. , Heydari S. , Amjadi A.

Open Physics

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2014

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tom 12

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nr 9

687-692

EN

In this paper, we consider a charged rotating black hole in three dimensions with a scalar charge, and discuss thermodynamics quantities. We find effects of the black hole parameters on the temperature, entropy, free energy, total energy and specific heat. We also investigate the stability of the black hole and study phase transition. We consider the first law of thermodynamics and find that satisfied.

2

Thermomechanics of Shells with Sigular Curves

100%

Makowski J. , Pietraszkiewicz W.

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2002

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tom nr 528/1487

1-100

EN

We formulate rigorously the global and local laws of mechanics and thermodynamics for shells with singularities at some stationary or moving curves in the shell base surface (itself not necessarily smooth). The laws are derived in an exact manner from underlying laws of continuum thermomechanics written in the integral - impulse form for the shell-like body. Our formulation is sufficiently general to include not only traditional applications to reversible problems of regular shells, but also those modeling irreversible and non-smooth processes in irregular shells. We assume that the shell-like body is represented in the physical space by the base surface' which in a reference configuration is only Lipschitz continuous with almost smooth boundary. By a moving singular curve we mean a one-parameter family of piecewise smooth surface curves which transverse the reference configuration of the shell base surface and across which various thermomechanical field variables may suffer jump discontinuities. However, all the fields are assumed to be regular enough for the generalized surface transport and gradient-divergence theorems to be applicable. As a result of complex transformations presented in the report, at regular points of the reference base surface and for almost all time instants we obtain five local laws of shell thermomechanics: the balance of mass, linear momentum, angular momentum, and energy as well as the entropy inequality. From the transformations we also obtain, corresponding to the laws of shell thermomechanics, five continuity conditions at regular points of every singular surface curve. Additionally, we discuss exact 2D shell kinematics and exact 2D shell strain measures. The principal features of the derived field equations and side conditions are: 1) the classical expressions for the linear and angular momenta are not assumed from the outset (they must be given by appropriate constitutive equations), 2) there is no classical splitting of the total energy into the sum of internal and kinetic energies (such a splitting is considered as a part of constitutive theory), 3) the entropy source and the entropy influx are not directly related to temperature, 4) there are two additional terms in the equation of energy balance which represent the interstitial working (they require a suitable constitutive prescription). We show that within the general shell thermomechanics the constitutive equations are needed for the surface stress tensor, the surface couple tensor, the specific total energy, the specific entropy, and the heat influx vector fields. But additionally we need the constitutive prescription for the linear and angular momenta vectors, as well as possibly for several other supplementary field variables. General expressions for the constitutive equations are given through response functionals of the histories of motion and temperature fields. For spatially first-grad "simple" shells we propose reduced forms of constitutive equations in the spatial and material representations. We also discuss additional constitutive assumptions which would allow us to eliminate temperatures, heats and entropy influxes at the upper and lower shell faces, as well as fields describing the interstitial working, the extra entropy source and the extra entropy flux. We derive the reduced dissipation inequality for shells and use it to develop thermodynamically consistent constitutive equations appropriate for heat conducting and thermo-visco-elastic shells. Particular forms of constitutive equations for thermoelastic, isothermal or higher-grad shells are proposed. By introducing thermodynamic potentials we also discuss constitutive nature of representing the total shell energy density as the sum of potential, kinetic and interstitial energy densities. Finally, we propose general and some specific forms of the kinetic constitutive equations for the linear and angular momenta. The results presented in this report may be considered as an introduction to a variety of thermomechanical problems of the regular and irregular shells, which might be formulated and solved already in the near future.

3

On the Navier-Stokes equations for water

100%

Piekarski S.

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2006

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tom Vol. 31, No. 2

265-271

EN

In general, the existence of entropy imposes restrictions on the constitutive functions in the Navier-Stokes equations. In this paper, it is shown that if the energy per unit mass is a function of the temperature Τ only, then the pressure p is an arbitrary function of the density ρ multiplied by the temperature Τ. However, for many fluids with the properties radically different than ideal gases (the best example here is water) the pressure as a function of ρ and Τ is not of the form p0(ρ)Τ. Therefore the energy density per unit mass in the Navier-Stokes equations for water should depend also on the mass density and the explicit form of this dependence requires further discussion.

4

Elements of thermodynamics in RNA evolution.

100%

Kierzek E. , Biała E. , Kierzek R.

Acta Biochimica Polonica

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2001

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tom 48

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nr 2

485-493

EN

The paper presents some aspects correlating thermal stability of RNA folding and the occurrence of structural motifs in natural ribonucleic acids. Particularly, the thermodynamic stability of 2'-5' and 3'-5' linked RNA and the contribution of unpaired terminal nucleotides (dangling ends) in secondary (2D) and tertiary (3D) structures of RNA are discussed. Both examples suggest that during evolution nature selected sequences and structures of RNA which are the most thermally stable and efficient for their biological function.

5

Axiomatic formulation of thermodynamics ideal gas laws

80%

Grzesikiewicz W. , Wakulicz A.

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2006

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tom Vol. 13, No. 2

103-110

EN

The relationships between physical quantities determining thermodynamic state of an ideal gas are analysed in the paper. It will be proved that such relationships can be obtained based on convex analysis of the formula describing specific energy of the gas. This formula is expressed as a functional with specific volume and specific entropy being its constrains. The resulting constitutive equations of ideal gas, determining pressure and temperature as a function of entropy and specific volume, are given. It will be proved that the equation of the ideal gas formulated by Clapeyron, can be easy obtain from the constitutive equations, eliminating the variable describing entropy. Moreover, it will be shown that the functional of specific energy of ideal gas is convex. Because of this mathematical property of the functional, Legendre transform is used in order to determine three conjugated functionals, i.e. enthalpy, free enthalpy and free energy. The method of description of thermodynamic relationships to be introduced herein, differs from well-known classic handbook’s presentations. Moreover, it permits a better understanding of the structure of thermodynamics equations.

6

Chronopotentiometry as a method for determining stability constants of metal complexes

80%

Kublanovsky V. S. , Litovchenko K. I. , Nikitenko V. N.

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1998

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tom Vol. 72, nr 12

2556-2563

EN

The complex formation of cadmium(II) with ethylenediaminetetraacetate (H4Edta), iminodiacetate (H2Imda) and glycine (HGl) has been studied by chronopotentiometry. It has been found that cadmium(II) forms with the above ligands complex ions of the compositions: CdHEdta(-), CdHEdta(2-), CdImda, Cd(Imda)(2-/2), CdGl(+) and CdGl2. The stability constants of the above complexes have been determined.

7

Druga zasada termodynamiki w analizie obiegów lewobieżnych. Część 4. Analizy liczbowe obiegów ziębniczych

80%

Nanowski D.

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2006

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tom nr 5

190-193

PL

Artykuł stanowi czwartą część cyklu publikacji, w którym w oparciu o drugą zasadę termodynamiki opisano jednostopniowy obieg lewobieżny przy pomocy odpowiednich przyrostów entropii oraz związanych z nimi przyrostów pracy napędowej, generujących rzeczywiste procesy nieodwracalne. W części pierwszej cyklu przedstawiono podstawowe zależności termodynamiczne, które wykorzystano do analizy obiegów ("TCHK" nr 4/2005). W części drugiej opisano wielkości charakteryzujące obieg lewobieżny, a także relację Gouy'a-Stodoli oraz pojęcie sprawności egzergetycznej ("TCHK" nr 6-7/2005). W części trzeciej omówiono rzeczywiste oddziaływania termiczne czynnika obiegowego i źródeł ciepła w obiegu Carnota pompy ciepła, a także znaczenie dochłodzenia ciekłego czynnika ("TCHK" nr 10/2005). W części czwartej autor prezentuje analizę liczbową efektywności energetycznej dla obiegu idealnego Carnota oraz nieodwracalnych obiegów chłodniczych Rankine'a i Lindego.

EN

This is the third part of the article consisting of five parts dealing with non-conventional thermodynamic analysis of the refrigeration cycles. On the basis of the second law of thermodynamics the refrigeration cycle has been described by means of the differences of entropy and appropriate works as effects of irreversible processes. Basic thermodynamic relationships useful for the analysis of the cycles have been presented in the first part of the paper ("TCHK" No. 4/2005). In the second part the basic quantities characterizing of the refrigeration cycles such as: work of the cycle, Gouy-Stodola relationship and exergy efficiency have been presented ("TCHK" No. 6-7/2005). In the third part of the paper real thermal impact of working medium and heat sources in Carnot cycle of heat pump as well as an effect of refrigerant subcooling have been presented ("TCHK" No. 10/2005). In the present part the numerical analysis of the thermal efficiency for ideal Carnot cycle as well as non-reversible Rankine and Linde cycles have been presented.

8

On non-equilibrium entropy in continuum thermodynamics of materials with memory

80%

Huet C.

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1999

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tom Vol. 51, nr 2

123-154

EN

Based on previous works of the author, the fundamentals of some basic concepts and methods currently used in the formulation of constitutive equations for linear or non-linear dissipative materials are revisited. The principles of the local state - or local equilibrium state - frequently used as the basis of Thermodynamics of Irreversible Processes in connection with the problem of the definition of a non-equilibrium entropy - are discussed, with emphasis laid on materials with memory exhibiting - as in linear or non-linear viscoelasticity - a delayed response to a constant loading. A adiabatic relaxation experiment is defined, from which it is shown that the usual formulation of the local state principle is too strong, since the set of relations which holds in equilibrium, and which makes use of macroscopic variables only, can never be applied without modification out of equilibrium. The same holds for the non-equilibrium Gibbs equation generally associated with the corresponding formalism when written with the real stress and temperature involved in the process. For dissipative behaviour of the differential type of order one, called also Markovian behaviour, a non-equilibrium entropy can be defined and some of the equilibrium relations can be applied to non-equilibrium situations. From this, a basic thermodynamic classification of rheological behaviour is obtained. In the non-Markovian case, the results are applied to the method of internal variables. A criterion for identifying suitable internal variables is obtained. They should correspond to Markovian behaviour when directly stimulated.

9

Synthesis of New Thia-Derivative Salens, Their Complexes with Copper(II) and Analytical Application for Potentiometric Sensors

80%

Saghatforoush L. A. , Ershad S. , Karim-nezhad G. , Aminkhani A. , Kabiri R.

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2007

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tom Vol. 81, nr 12

2069-2069

EN

Three new salen derivative ligands (L1, L2 and L3), containing mixed-ligand donor sets of NSNO, have been synthesized. The thermodynamics of complexation reaction between new synthesized salens and copper(II) ion in acetonitrile solution was studied by conductometric method. Formation constants of the resulting 1:1 complex was determined from the conductance-moleratio data. The results have shown that the new salens, as a neutral chelating agent formed selective and stable complex with Cu(II) ion. Thus, the L1 new salen compound was used as neutral ion carrier in the construction of a Cu2+-PVC membrane electrode. The influence of some exper i mental parameters such as membrane composition, nature and amount of plasticizer, additive and concentration of internal solution on the potential response of the Cu2+-sensor were investigated. The electrode exhibits a Nernstian response for Cu2+-over wide concentration range (5.0×10-6-1.0×10-1 M) with a slope 29.7š0.5 mV/decade and detection limit 1.0×10-6 M. It could be used in a pH range of 4.0-8.0. The electroe shows excellent discriminating ability to wards Cu2+ ion with regard to several alkaliand alkaline earth metal ions. It has a fast response time of about 20 s. The proposed sensor as an indicator electrode was used success fully in the potentiometric titra tion of Cu2+-ions with EDTA.

10

Hydrodynamic cavitation: from theory towards a new experimental approach

80%

Lucia U. , Gervino G.

Open Physics

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2009

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tom 7

|

nr 3

638-644

EN

Hydrodynamic cavitation is analysed by a global thermodynamics principle following an approach based on the maximum irreversible entropy variation that has already given promising results for open systems and has been successfully applied in specific engineering problems. In this paper we present a new phenomenological method to evaluate the conditions inducing cavitation. We think this method could be useful in the design of turbo-machineries and related technologies: it represents both an original physical approach to cavitation and an economical saving in planning because the theoretical analysis could allow engineers to reduce the experimental tests and the costs of the design process.

11

Molecular interaction in Langmuir monolayers - statistical thermodynamics approach

80%

Dynarowicz-Łątka P. , Jawień W. , Minones Trillo J. , Vila Romeu N. , Conde Mouzo O.

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1998

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tom Vol. 46, No. 2

195-206

EN

A regular solution theory for a two-dimensional system with three components of different molecular sizes, adapted from statistical thermodynamics, is used to derive equations describing parameters related to the molecular interactions in mixed Langmuir monolayers. The theory has been applied by examining interactions at the interface for the mixed system of 1-hexadecanol and 1,16-hexadecanediol spread at the water/air interface, basing on experimental data of surface pressure/area (/area (p/A) isotherms. The obtained results show that the attractive forces between film-forming molecules are much stronger than those between particular amphiphiles and water.

12

On the thermodynamics of phase transitions in metal hydrides

80%

Vita A.

Open Physics

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2012

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tom 10

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nr 1

86-95

EN

Metal hydrides are solutions of hydrogen in a metal, where phase transitions may occur depending on temperature, pressure etc. We apply Le Chatelier’s principle of thermodynamics to a particular phase transition in TiHx, which can approximately be described as a second-order phase transition. We show that the fluctuations of the order parameter correspond to fluctuations both of the density of H+ ions and of the distance between adjacent H+ ions. Moreover, as the system approaches the transition and the correlation radius increases, we show -with the help of statistical mechanics-that the statistical weight of modes involving a large number of H+ ions (‘collective modes’) increases sharply, in spite of the fact that the Boltzmann factor of each collective mode is exponentially small. As a result, the interaction of the H+ ions with collective modes makes a tiny suprathermal fraction of the H+ population appear. Our results hold for similar transitions in metal deuterides, too. A violation of an -insofar undisputed-upper bound on hydrogen loading follows.

13

Thermodynamics of Solubility of Solids in Liquids

80%

Buchowski H. , Książczak A.

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1999

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tom Vol. 73, nr 10

1631-1663

EN

The most important results of the experimental and theoretical studies of solid-liquid-vapor equilibria carried out in the Department of Physical Chemistry at Warsaw University of Technology between 1975-1995 are reported. The thermodynamic expressions for the solvent activity, the solubility and the excess functions of mixing along the liquids of an eutectic system have been derived by integration of Gibbs-Duhem relation.

14

Planck-scale corrections to Friedmann equation

80%

Awad A. , Ali A.

Open Physics

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2014

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tom 12

|

nr 4

245-255

EN

Recently, Verlinde proposed that gravity is an emergent phenomenon which originates from an entropic force. In this work, we extend Verlinde’s proposal to accommodate generalized uncertainty principles (GUP), which are suggested by some approaches to quantum gravity such as string theory, black hole physics and doubly special relativity (DSR). Using Verlinde’s proposal and two known models of GUPs, we obtain modifications to Newton’s law of gravitation as well as the Friedmann equation. Our modification to the Friedmann equation includes higher powers of the Hubble parameter which is used to obtain a corresponding Raychaudhuri equation. Solving this equation, we obtain a leading Planck-scale correction to Friedmann-Robertson-Walker (FRW) solutions for the p = ωp equation of state.

15

Thermodynamic parameters of hydrocarbon adsorption on solid surfaces.

80%

Dmitrieva Z. T. , Bylina I. V. , Velikov A. A.

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tom Vol. 9, nr 56

415-420

EN

Using a microcalorimetric technique, kinetic isotherms of adsorption heats have been obtained for aliphatic and aromatic hydrocarbons on the surfaces of polymer and natural sorbents at 293-323 K. Thermodynamic and kinetic parameters, equlibrium character and direction of the process of hydrocarbon sorption have been determined. The relationships between the thermodynamic characteristics and the structure and chemical nature of the adsorbent have been established and revealed.

16

Potentiometric and Thermodynamic Studies of 3-(Trichlorophenylsulphonamido)rhodanine Complexes with Some Metal Ions

80%

Hassanein A.

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2000

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tom Vol. 74, nr 7

903-907

EN

Acid dissociation and complex stability constants of 3-(tricholophenylsulphonamido)rhodanine (TCSR) with some metal ions were determined potentiometrically in 0.1 KCl and 30% (v/v) sthanol-water mixture. The sequence of stability constants is: Th4 UO2+ 2 Cu2+ Ni2+ Co2+ n2+. The dissociation constants pK11 of TcSR and the stability constants log K of their complexes were determined at 298, 308 and 318 K. The corresponding therodynaic paraeters (deltaG, deltaH and deltaS) were derived and discussed. The dissociation process is non-spontaneous, endothermic and entropically unfavourable. The formation of the metal complexes has been found to be endothermic and entropically favourable.

17

Synthesis of a New triazine Derived Macrocycle and a Thermodynamic Study of Its Complexes with Some Transition and heavy Metal Ions in Acetonitrile Solution

80%

Pourghobadi Z. , Seyyed F. , Daghighi-Asli M.

|

2000

|

tom Vol. 74, nr 6

837-846

EN

A synthetic procedure has been developed for the preparation of a new triazine derived macrocycle (13,29-diphenyl-4,7,20,23-tetraoxa-1,10,12,14,16,17,26,28,30,32-decaza-[10,10](2,6)triazinophane). The formation of some transition and heavy etal complexes with the macrocycle was investigated in acetonitrile solution conductometrically at different temperatures. The formation constants of the resulting 1:1 complexes were determined from the molar conductance-mole ratio data and found to vary in the sequence Hg2+ Pb2+ Cd2+ - Ag+ Cu2+ Tl+ Co2+ Ni2+ Zn2+. The enthalpy and entropy of complexation reactions were determined fro the temperature dependence of the formation constants. In all cases, the complexes were found to be enthalpy stabilized but entropy destabilized.

18

Modele teoretyczne do obliczeń współczynników aktywności tlenu w ciekłych stopach Ni-Cu

80%

Jerzak W.

|

2011

|

tom R. 56, nr 7-8

420-424

PL

W artykule przedstawiono sposób wyznaczenia współczynników aktywności tlenu według Raoulta, dla ciekłych stopów Ni-Cu w temperaturach 1773 K i 1823 K o zróżnicowanej zawartości Cu, z wykorzystaniem różnych modeli teoretycznych. Brali wiedzy na temat niektórych parametrów oddziaływania sprawił, iż w artykule zaprezentowano metodykę wyznaczenia dwuskładnikowych parametrów oddziaływania typu Redlich-Kister do modelu opartego na formalizmie kwadratowym. Aby dokonać takiego zabiegu, należało wykorzystać zależności wiążące ze sobą parametry oddziaływania pierwszego rzędu w rozwinięciu według ułamków molowych So(Cu)-eo(Ni) oraz współczynniki aktywności tlenu w ciekłym niklu oraz miedzi. Przeprowadzone obliczenia, połączone z wyborem optymalnych współczynników aktywności tlenu w czystych metalach, pozwoliły na lepsze odwzorowanie wyników eksperymentów od prezentowanych do tej pory w literaturze rozwiązań.

EN

The method of estimating the oxygen activity coefficient, according to Raoult, for the liquid Ni-Cu alloys - of a variable Cu content - at temperatures 1773 K and 1823 K is presented in the paper upon four theoretical models. The Ni-Cu alloys, not Cu-Ni alloys, were considered due to the fact that the reference state, for the activity coefficient calculation on the bases of experiments, was pure nickel. Activity coefficients and interaction parameters are the values which can not be directly measured, but can be experimentally determined. However, it should be remembered, that the determination of these values for all liquid alloys at arbitrary temperatures is practically impossible. Therefore several scientists created or modified the previously known models describing systems of the Ni-Cu-O type. Usually models are determined on the given system of elements and transferring them into another system requires new parameters for the model. Calculating the oxygen activity coefficients at an infinite dilution for an arbitrary composition of the Ni-Cu alloy requires the knowledge of these components' interactions in a liquid solution. The method of the determination of binary interaction parameters of the Redlich-Kister model based on the quadratic formalism, is described in this paper. In order to perform such operation, relationships between first order the interaction parameters in expansion abased on the mole fractions and the oxygen activity coefficients in liquid nickel and copper, should be used. The performed calculations - combined with the selection of the optimal values of the oxygen activity coefficients in pure metals - enabled the better representation of the experimental results than the solutions presented so far in the references.

19

Thermodynamics of Substituted Pyrazolone : VI. Potentiometric and Conductometric Studies of Complexes of Some Transition Metals with 4-(4-Acetophenyl)hydrazono-3-methyl-1-phenyl-2-pyrazolin-5-one

80%

El-Bindary A. , El-Sonbati A. , Kera H.

|

2000

|

tom Vol. 74, nr 2

239-244

EN

The dissociation constant of 4-(4-acetophenyl)hydrazono-3-methyl-1-phenyl-2-pyrazolin-5-one (AHMPP) has been determined potentiometrically in 0.1 M KCl and 50% (v/v) ethanol-water mixture. Also, the stepwise stability constants of the formed complexes of Mn2+, Co2+, Ni2+, Cu2+, Zn2+, La3+, Ce3+, UO2+2 and Th4+ with AHMPP have been determined. The stability of the formed complexes follow the sequence: Th4+ UO2+2 Ce3+ La3+ Mn2+ Co2+ Ni2+ Cu2+ Zn2+ The thermodynamic parameters (deltaG, delta H and deltaS) for AHPP and its complexes were evaluated and discussed. The dissociation process is nonspontaneous, endothermic and entropically unfavourable. The formation of the metal complexes has been found to be spontaneous, exothermic or endothermic (depends on the metal) and entropically favourable. The stoichiometries of these complexes were determined conductometrically indicating the formation of 1:1 and 1:2 (etal:ligand) complexes.

20

On the solubility of chain alcohols in supercritical carbon dioxide

70%

Gregorowicz J. , Chyliński K.

|

1998

|

tom Vol. 72, nr 5

877-885

EN

The phase behaviour in the CO2-n-alkanol family was presented and its influence on the solubility measurements was discussed. A linear relationship is suggested between the logarithm of solubility of liquid n-alkanols in supercritical CO2 and the carbon number of the solute. The hypothesis based on experimental data is supported by thermodynamic considerations. Solubilities of 1-hexanol at 311 K and 1-decanol at 313 K were measured in order to extend the group substances studied in this paper.