Enthalpies of Mixing for the Liquid System Formic Acid + Acetic Acid

1979 ◽  
Vol 34 (5) ◽  
pp. 659-660
Author(s):  
R. Haase ◽  
H.-J. Jansen ◽  
K. Puder ◽  
B. Winter
Keyword(s):  
Acetic Acid ◽  
Formic Acid ◽  
Mole Fraction ◽  
Excess Enthalpy ◽  
Liquid System ◽  
Short Description ◽  
Enthalpies Of Mixing ◽  
Calorimetric Measurements ◽  
C 30 ◽  
Increasing Temperature

Abstract After a short description of the evaluation of the calorimetric measurements, we give the results for the enthalpies of mixing in the liquid system formic acid + acetic acid. The molar excess enthalpy H̄E has been determined as a function of the mole fraction x of acetic acid at 18 °C, 20 °C, 25 °C, 30 °C, and 40 °C. The function H̄E (x) is always positive and nearly symmetric (with a maximum at about x = 0.5) and increases with increasing temperature. A three-parameter fit of the function H̄E (x) has been achieved for each temperature.

Enthalpies of Mixing for Binary Liquid Mixtures of Acids

1983 ◽  
Vol 38 (12) ◽  
pp. 1400-1401 ◽  
Author(s):  
R. Haase ◽  
H.-J. Jansen ◽  
B. Winter
Keyword(s):  
Acetic Acid ◽  
Formic Acid ◽  
Propionic Acid ◽  
Entire Range ◽  
Excess Enthalpy ◽  
Liquid Mixtures ◽  
Binary Liquid ◽  
Calorimetric Measurements ◽  
Liquid Systems ◽  
C 30

Abstract For the binary liquid systems formic acid + acetic acid, formic acid + propionic acid, and acetic acid + propionic acid, we give the results of new calorimetric measurements of the molar excess enthalpy H̄E at 25 °C, 30 °C, 40 °C, and 60°C, covering the entire range of compositions. H̄E is always positive, increases linearly with the temperature, and is slightly asymmetric with respect to the mole fraction x. The composition at the maximum of the function H̄E(x) is independent of the temperature.

scholarly journals Notizen:Mischungsenthalpien beim flüssigen System Wasser + Essigsäure / Heats of Mixing for the Liquid System Water + Acetic Acid

1972 ◽  
Vol 27 (10) ◽  
pp. 1527-1529 ◽  
Author(s):  
R. Haase ◽  
P. Steinmetz ◽  
K.-H. Dücker
Keyword(s):  
Acetic Acid ◽  
Power Series ◽  
Liquid System ◽  
Heat Of Mixing ◽  
Pure Liquid ◽  
Calorimetric Measurements ◽  
Heats Of Mixing ◽  
Free Parameters ◽  
C 30 ◽  
System Water

Calorimetric measurements of the heats of mixing for the liquid system water+acetic acid at 17 °C, 20 °C, 25 °C, 30 °C, 40 °C, and 50 °C show that there is a change of sign in the function H̅E(x), where H̅E denotes the molar heat of mixing and x the mole fraction of acetic acid. The process of mixing the pure liquid components is weakly exothermic for low acid concentrations, but strongly endothermic for high acid concentrations. The function H̅E can be approximately represented by the usual power series with respect to x, five free parameters at each temperature being necessary.

scholarly journals Verdampfungsgleichgewicht und thermodynamisehe Funktionen des flüssigen Systems Wasser + Essigsäure / Vapour-Liquid. Equilibrium and Thermodynamic Functions of the Liquid System Water + Acetic Acid

1973 ◽  
Vol 28 (10) ◽  
pp. 1740-1742 ◽  
Author(s):  
R. Haase ◽  
M. Pehlke ◽  
K.-H. Dücker
Keyword(s):  
Acetic Acid ◽  
Composition Dependence ◽  
Excess Enthalpy ◽  
Excess Entropy ◽  
Liquid System ◽  
Gibbs Function ◽  
Liquid Equilibrium ◽  
Molar Excess ◽  
C 30 ◽  
System Water

Vapour pressures and vapour compositions of the liquid system water + acetic acid have been measured at 25 °C, 30 °C, 35 °C, 40 °C, and 45 °C in the whole range of compositions. The dimerization of acetic acid in the vapour being taken into account, the molar excess Gibbs function ḠE is derived from the measurements. Earlier measurements of the molar excess enthalpy HE are combined with the -GE values to give the molar excess entropy SE. The “symmetry rule” (Haase, 1951) concerning the composition dependence of ḠE, -HE, and S̄E has been confirmed.

Notizen: Diffusion in the Liquid System Chloroform + Methyl Acetate

1986 ◽  
Vol 41 (11) ◽  
pp. 1337-1338 ◽  
Author(s):  
R. Haase ◽  
W. Engels
Keyword(s):  
Diffusion Coefficient ◽  
Mole Fraction ◽  
Activity Coefficients ◽  
Linear Relation ◽  
Methyl Acetate ◽  
Composition Dependence ◽  
Liquid System ◽  
C 30

We present and discuss the results of measurements of the diffusion coefficient D and the activity coefficients as functions of the mole fraction x of one of the components in the liquid system chloroform + methyl acetate at 10 °C, 30 °C, and 50 °C. The function D(x) exhibits a pronounced maximum at each temperature, while the kinematic diffusion coefficient D*, considered as function of x, shows a flat minimum, its composition dependence being nearer to a linear relation than that of D(x).

Pretreatment of hardwood chips via autohydrolysis supported by acetic and formic acid

Holzforschung ◽  
2014 ◽  
Vol 68 (4) ◽  
pp. 401-409 ◽  
Author(s):  
Mehmet Sefik Tunc ◽  
Juben Chheda ◽  
Evert van der Heide ◽  
Jerry Morris ◽  
Adriaan van Heiningen
Keyword(s):  
Acetic Acid ◽  
Formic Acid ◽  
Condensation Products ◽  
Increasing Temperature ◽  
Sugar Hydrolysis

Abstract A mixture of US southern hardwood chips was treated with aqueous acetic and formic acid (FA) solutions in a modified Dionex ASE100 extractor. The amount and selectivity of hemicelluloses dissolution increase at higher acetic acid (AA) and FA concentrations, but cellulose remains intact in the residual wood. Even at the highest AA concentration of 100 g l-1, the dissolved hemicellulose fragments are still oligomeric except for arabinose. The formation of lignin-like condensation products (LCPs) and decomposition of dissolved mannose, arabinose, and galactose were observed at the highest AA concentration. Sugar hydrolysis is more pronounced with the addition of FA at increasing temperature. The concentration of xylose in the FA extract is approximately the same as that of xylo-oligomers at 160°C. Formation of LCPs is only observed at 170°C during 10 g l-1 FA treatment. The concentrations of dissolved wood components increase linearly with increased recycling of the FA extract.

Leitfähigkeit des flüssigen Systems Ameisensäure + Essigsäure / Conductivity of the Liquid System Formic Acid + Acetic Acid

1975 ◽  
Vol 30 (3) ◽  
pp. 391-393
Author(s):  
R. Haase ◽  
H. Jaramillo- Giraldo ◽  
K.-H. Dücker
Keyword(s):  
Activation Energy ◽  
Acetic Acid ◽  
Formic Acid ◽  
Molar Volume ◽  
Electric Conductivity ◽  
Composition Range ◽  
Liquid System ◽  
Equivalent Conductivity

Results of measurements of the electric conductivity and of the molar volume for the water-free liquid system formic acid-f-acetic acid are presented. They cover the whole composition range at temperatures between 0 °C and 50 °C. The equivalent conductivity and the activation energy are also given.

Thermodynamic Excess Functions for the Liquid System W ater + Acetic Acid from Calorimetric Data

1977 ◽  
Vol 32 (5) ◽  
pp. 507-510 ◽  
Author(s):  
R. Haase ◽  
M. Pehlke
Keyword(s):  
Acetic Acid ◽  
Composition Dependence ◽  
Liquid System ◽  
Pure Liquid ◽  
Excess Functions ◽  
Molar Excess ◽  
Molar Excess Volume ◽  
Thermodynamic Excess Functions ◽  
C 30 ◽  
System Water

Abstract For the liquid system water + acetic acid, we give the results of new calorimetric measurements regarding the molar excess enthalpy H̅E for 25 °C, 30 °C, 35 °C, 40 °C, 55 °C, and 70 °C, covering nearly the entire range of com­ positions. The experimental data show that H̅E is positive for all compositions and temperatures except in the region of low acid concentrations at temperatures below 55 °C where the process of mixing the pure liquid components is exothermic (H̅E<0). Using values of the molar excess Gibbs function G̅E (always positive) derived from earlier data on vapour-liquid equilibria, we compute the molar ex­cess entropy S̅E which is always negative. The “symmetryrule” concerning the composition dependence of G̅E (as compared to that of H̅E and S̅E) has again been confirmed. The composition dependence of S̅E is similar to that of the molar excess volume.

Zum thermodynamischen Verhalten des flüssigen Systems Wasser + Essigsäure / On the Thermodynamic Behaviour of the Liquid System Water + Acetic Acid

1974 ◽  
Vol 29 (9) ◽  
pp. 1383-1384
Author(s):  
R. Haase ◽  
M. H. Keller ◽  
K.-H. Dücker
Keyword(s):  
Acetic Acid ◽  
Excess Enthalpy ◽  
Excess Entropy ◽  
Liquid System ◽  
Heat Of Mixing ◽  
Gibbs Function ◽  
Molar Excess ◽  
Thermodynamic Behaviour ◽  
Experimental Values ◽  
System Water

Vapour pressures and vapour compositions of the liquid system water+acetic acid have been measured at 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, and 75 °C in the whole range of compositions. The molar excess Gibbs function is derived from the measurements. At 50 °C, where experimental values of the molar excess enthalpy (molar heat of mixing) are available, the molar excess entropy is also given.

Excess molar volumes of binary mixtures of acetic acid and propionic acid with some members of homologous series of alkanes

1991 ◽  
Vol 56 (4) ◽  
pp. 736-744 ◽  
Author(s):  
Ondřej Drábek ◽  
Ivan Cibulka
Keyword(s):  
Acetic Acid ◽  
Propionic Acid ◽  
Alkyl Chain ◽  
Excess Molar Volumes ◽  
Liquid Mixtures ◽  
Entire Concentration Range ◽  
Molar Volumes ◽  
Binary Liquid ◽  
Alkane Molecule ◽  
Increasing Temperature

Excess molar volumes of binary liquid mixtures of (acetic or propionic acid = hexane) at 25 and 35°C, and (acetic or propionic acid + heptane or octane) and (acetic acid + dodecane) at 25°C, measured with a tilting dilution dilatometer, are reported. The excess volumes are positive over the entire concentration range for all mixtures and increase with increasing length of an alkane molecule, decrease with increasing of the alkyl chain in a molecule of carboxylic acid, and increase with increasing temperature.

Confirmatory Tests for Aflatoxin B1

1964 ◽  
Vol 47 (5) ◽  
pp. 801-803 ◽  
Author(s):  
Peter John Andrellos ◽  
George R Reid
Keyword(s):  
Acetic Acid ◽  
Thin Layer ◽  
Formic Acid ◽  
Thionyl Chloride ◽  
Aflatoxin B1 ◽  
Trifluoroacetic Acid ◽  
Reaction Products ◽  
Confirmatory Tests ◽  
Aflatoxin B ◽  
Layer Chromatography

Abstract Three confirmatory tests have been devised to identify aflatoxin B±. Portions of the isolated toxin are treated with formic acid-thionyl chloride, acetic acid-thionyl chloride, and trifluoroacetic acid, respectively, and aliquots of the three fluorescent reaction products are spotted on thin-layer chromatography plates. Standards treated with each of the three reagents, plus an untreated standard, are spotted on the same plate, and after development the spots are compared under ultraviolet light.

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