Heats of formation of RuO4, RuO42−, and related compounds

1969 ◽  
Vol 47 (4) ◽  
pp. 581-586 ◽  
Author(s):  
E. E. Mercer ◽  
D. T. Farrar
Keyword(s):  
Sodium Periodate ◽  
Heats Of Formation ◽  
Basic Solution ◽  
Heat Of Reaction ◽  
Kcal Mole ◽  
Heats Of Reaction ◽  
Related Compounds

The heat of reaction of ruthenium metal with bromine in basic solution, according to the equation[Formula: see text]has been measured calorimetrically. In addition, the heat of oxidation of barium ruthenate hydrate by sodium periodate to form RuO4(aq) has been determined. From these heats of reaction, and several other heats measured here, the heats of formation of several ruthenium species have been calculated. The more important of these are: Na2RuO4(aq), ΔHf = −224.1 ± 0.8; RuO42−(aq), ΔHf = −109.4 ± 1.0; RuO4(aq), ΔHf = −57.5 ± 1.1; RuO4(l), ΔHf = −57.0 ± 1.1 kcal/mole.

The solubility of potassium from soil illites. V. Interlayer hydrogen ions; heats of reaction; and synopsis

Soil Research ◽  
1967 ◽  
Vol 5 (2) ◽  
pp. 203 ◽  
Author(s):  
BM Tucker
Keyword(s):  
Calcium Chloride ◽  
Calcium Ions ◽  
Temperature Rise ◽  
Chloride Solution ◽  
Calcium Chloride Solution ◽  
Hydrogen Ion ◽  
Heat Of Reaction ◽  
Hydrogen Ions ◽  
Kcal Mole ◽  
Heats Of Reaction

When potassium is readsorbed at interlayer sites in soil illites after displacement in calcium chloride solution, hydrogen ions are released in proportions ranging from 1/6 to 1/10 of the potassium adsorbed. This supports the conclusions of earlier work that release of potassium by calcium ions from these sites requires the intervention of hydrogen ions in the approximate ratio of one hydrogen ion to three calcium ions. The release of potassium increased about 1.4 times for a temperature rise from 10 to 30�C. The heat of reaction was 3 or 4 kcal/mole potassium released. This is consistent with a reaction between ions and charged sites as the heats of many ionic reactions are of this magnitude; and it appears to be less than the heats of decomposition of the clay mineral lattice. A summary of the findings of Parts I-V of this series appears in the Synopsis

A calorimetric study of periodate species in aqueous solution

1968 ◽  
Vol 46 (16) ◽  
pp. 2679-2683 ◽  
Author(s):  
E. E. Mercer ◽  
D. T. Farrar
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Sodium Periodate ◽  
Ionization Constant ◽  
Periodic Acid ◽  
Heats Of Formation ◽  
Calorimetric Study ◽  
Kcal Mole ◽  
Acid Ionization Constant ◽  
Acid Ionization

Heats of several reactions involving sodium periodate, NaIO4(c), have been measured in an isothermal jacketed calorimeter. The apparent acid ionization constant of periodic acid was redetermined at an ionic strength of 0.13. From these data the following values for heats of formation at 25.00° have been calculated: NaIO4(c), −105.15 ± 0.30; IO4−(aq), −38.8 ± 0.4; H5IO6(aq), −188.9 ± 1.0; H4IO6−(aq), −186.3 ± 1.0 kcal/mole.

A thermodynamic study of the dimerization of cyclopentadiene

1968 ◽  
Vol 21 (7) ◽  
pp. 1789 ◽  
Author(s):  
AG Turnbull ◽  
HS Hull
Keyword(s):  
Liquid Phase ◽  
Rate Constant ◽  
Vapour Pressure ◽  
Boiling Point ◽  
Strain Energy ◽  
Order Rate Constant ◽  
Adiabatic Calorimeter ◽  
Thermodynamic Study ◽  
Heats Of Formation ◽  
Kcal Mole

The heat of dimerization of cyclopentadiene to endo-dicyciopentadiene in the liquid phase at 25� was measured in an adiabatic calorimeter to be -9.22 � 0.3 kcal/mole monomer. The rate of dimerization in the liquid phase at 25� was followed with a dilatometer and the initial second-order rate constant found to be 4.99 x 10-5. mole-l min-l. The vapour pressure of endo-dicyclopentadiene, measured by a boiling point method in the range 77.5-149.6�, gave the relation (p in torr): RInp ? 11342/T -2.6505In T + 54.7855 The standard heats of formation of solid, 31.1 � 0.5 kcal/mole, and gaseous, 42.2 � 0. 6 kcal/mole, endo-dicyclopentadiene were derived, and the strain energy and dimerization equilibria discussed.

Diazen und andere Distickstoffhydride: Bildungswärmen, Dissoziationsenergien, Auftrittspotentiale, Protonenaffinitäten [1] / Diazene and other Dinitrogen Hydrides: Heats of Formation, Dissoziation Energies, Appearance Potentials, Proton Affinities [1]

1979 ◽  
Vol 34 (10) ◽  
pp. 1385-1390 ◽  
Author(s):  
Nils Wiberg ◽  
Gerd Fischer ◽  
Heinz Bachhuber
Keyword(s):  
Hydrogen Atom ◽  
Proton Affinity ◽  
Heat Of Formation ◽  
Heats Of Formation ◽  
Proton Affinities ◽  
Kcal Mole ◽  
Energy Data

AbstractIonisation and appearance potentials were obtained for diazene HN = NH (prepared by thermolysis of TOSN2H2M, M = Li, Na, K), isodiazene H2N = N (prepared by thermolysis of TOSN2H2CS and N2H4 microwave radiolysis, respectively), and other hydrides N2Hn (cf. Table I). The following energy data (kcal/mole) have been determined for diazene: heat of formation (32), enthalpy of isomerisation to isodiazene (13), NN-dissoziation energy (122), NH-dissoziation energy (81), hydrogen atom affinity (45), proton affinity (176).

Heats of Reaction of Natural Rubber with Sulfur

1970 ◽  
Vol 43 (6) ◽  
pp. 1275-1293 ◽  
Author(s):  
N. Bekkedahl ◽  
J. J. Weeks
Keyword(s):  
Hydrogen Sulfide ◽  
Standard Deviation ◽  
Natural Rubber ◽  
Volume Change ◽  
Side Reaction ◽  
Enthalpy Change ◽  
Heat Of Reaction ◽  
Use Of Data ◽  
Heats Of Reaction

Abstract An adiabatic copper calorimeter was used to determine the heats of vulcanization of pale crepe natural rubber with sulfur for mixtures varying in composition from 0 to 32 per cent added sulfur. The side reaction that produces hydrogen sulfide was avoided by using reaction temperatures near 155° C. Heats of reaction at 25° C and at 155° C are reported. The enthalpy change at 25° C for compounds containing up to about 18 per cent sulfur is given in joules per gram of vulcanizate by the equation, ΔH25=−21.1·S with a standard deviation of 11 J/g. Here S is the percentage of combined sulfur. Above 18 per cent sulfur the heat of reaction at 25° C remains approximately constant at 380 ± 8 J/g. A comparison is made between the heat of vulcanization and the volume change on vulcanization, both as functions of combined sulfur, by making use of data in the literature.

Ionisierungs- und Auftrittspotentialmessungen an Dialkylsulfoxiden

1975 ◽  
Vol 30 (3) ◽  
pp. 340-346
Author(s):  
Peter Potzinger ◽  
Heinz-Ulrich Stracke ◽  
Wolfgang Küpper ◽  
Klaus Gollnick
Keyword(s):  
Dissociation Energy ◽  
Heats Of Formation ◽  
Kcal Mole ◽  
Dissociation Energies ◽  
Fragment Ions ◽  
A Value

Ionisation- and appearance potentials of some dialkylsulfoxides and their major fragment ions were determined. In addition to the determination of dissociation energies in the ions and heats of formation of the ions and ionic fragments, a value of 66 kcal/mole for the C-S dissociation energy in neutral dialkyl sulfoxides was obtained.

Heat of Reaction Measurements of Sodium Borohydride Alcoholysis

2005 ◽  
Author(s):  
Jinsong Zhang ◽  
T. S. Fisher ◽  
Jay P. Gore ◽  
P. Veeraraghavan Ramachandran
Keyword(s):  
Ethylene Glycol ◽  
Sodium Borohydride ◽  
Aqueous System ◽  
Heat Of Reaction ◽  
New Approach ◽  
On Demand ◽  
Heats Of Reaction ◽  
Prior Literature ◽  
Storage Methods ◽  
The Cost

On-board hydrogen storage has been identified as one of the most challenging technical barriers to the transition from gasoline to hydrogen powered vehicles. The Hydrogen-On-Demand™ system patented by Millenium Cell Inc. uses sodium borohydride and water to generate hydrogen when needed. The system has many advantages over other types of storage methods such as compressed hydrogen, liquid hydrogen and metal hydrides. Nevertheless, the cost of making and regenerating sodium borohydride is too high. A recently filed patent indicates that sodium borohydride alcoholysis (e.g. using ethylene glycol) may offer some advantages over the aqueous system in terms of regeneration, which may significantly reduce the cost to regenerate sodium borohydride. To begin evaluating the energy efficiency of this new approach, this work experimentally characterizes the heat of reaction of sodium borohydride with ethylene glycol. The heat of reaction was measured to be approximately 220 kJ/mol (exothermic). For the sodium borohydride and water reaction, two different heat of reaction values have been reported in prior literature. The present work shows that the heats of reaction for both sodium borohydride hydrolysis and alcoholysis are both near 220 kJ/mol exothermically.

The protonation reactions of catechin, epicatechin and related compounds

1984 ◽  
Vol 37 (4) ◽  
pp. 885 ◽  
Author(s):  
JA Kennedy ◽  
MHG Munro ◽  
HKJ Powell ◽  
LJ Porter ◽  
LY Foo
Keyword(s):  
Time Scale ◽  
Protocatechuic Acid ◽  
Equilibrium Constants ◽  
Basic Solution ◽  
Ionic Mechanism ◽  
Model Compounds ◽  
Specific Solvation ◽  
Experimental Time ◽  
Protonation Sequence ◽  
Related Compounds

The protonation reactions for catechin and epicatechin have been studied at 25�C, I 0.10M (KCl). Equilibrium constants Kn for the protonation steps of the anions L4- have been determined from potentiometric and/or spectrophotometric measurements. The logKn values for the epimers differed significantly only for logKl and logK4 (values for catechin 13.26 � 0.05, 11.26 � 0.06, 9.41 � 0.02, 8.64 � 0.01, and epicatechin 13.40 � 0.05, ll.23 � 0.06, 9.49 � 0.02, 8.72 � .01, n = 1-4 respectively). These differences are ascribed to specific solvation effects or ion associations between K+ and the ligand anions. Epimerization was studied by h.p.l.c., and was found to be minimal over the experimental time scale at pH c. 13.5. The ring on which each stepwise protonation occurs was elucidated by reference to log Kn values measured for the model compounds catechol, 4-methylbenzene-1,2-diol, protocatechuic acid and 3',4'-di-O-methylcatechin. The protonation sequence is B ring, A ring, B ring and A ring. In contrast to earlier results, it has been established that the epimerization of catechin or epicatechin at C2, and the formation of catechinic acid in basic solution, may proceed through a radical rather than ionic mechanism.

Sign in / Sign up

Export Citation Format

Share Document