Evaluation of Unbonded O—H Groups for HDO in Liquid D2O from Infrared Absorptivity Measurements

1972 ◽  
Vol 50 (11) ◽  
pp. 1655-1665 ◽  
Author(s):  
E. C. W. Clarke ◽  
D. N. Glew
Keyword(s):  
Temperature Dependence ◽  
Equilibrium Constant ◽  
Standard Enthalpy ◽  
Liquid State ◽  
Low Temperatures ◽  
Enthalpy Change ◽  
Weak Band ◽  
Equilibrium Quotient ◽  
Standard Enthalpy Change

Wyss and Falk's infrared absorptivities between 10 and 85 °C for HDO in liquid D2O in the fundamental O—H stretch region have been analyzed numerically and show a statistically significant weak band near 3600 cm−1 at each temperature. This band, the Raman analog of which was reported earlier, confirms the presence of HDO species with unbonded O—H groups in the liquid state. The percentage of HDO species with un-bonded O—H groups is found to be 4.6, 6.1, 10.1, and 11.9, respectively, at 10, 35, 60, and 85 °C.The four predominant HDO species in equilibrium at low temperatures are denned together with their equilibrium constant for the [Formula: see text] bond-rupturing process. A standard enthalpy change of ΔH° = 6800 ± 1100 cal is found for the rupture of one mole of [Formula: see text] bonds. This is in contrast with the apparent enthalpy change of 2900 ± 500 cal, as usually derived from the temperature dependence of the equilibrium quotient. Approximate mole fractions for each of twelve differently bonded HDO species are derived from a model for random H- and D-bond statistics. Results show that the four predominant HDO species give a full interpretation of the absorptivities at 10, 35, and 60 °C but that additional minor species contribute slightly to the absorptivity at 85 °C.

Adsorption of Liquids and Swelling of Wood IV. Temperature Dependence on the Adsorption

Holzforschung ◽  
1999 ◽  
Vol 53 (6) ◽  
pp. 669-674 ◽  
Author(s):  
Kei Morisato ◽  
Hitoshi Kotani ◽  
Yutaka Ishimaru ◽  
Hiroyuki Urakami
Keyword(s):  
Free Energy ◽  
Temperature Dependence ◽  
Standard Enthalpy ◽  
Cell Walls ◽  
Standard Free Energy ◽  
Isosteric Heat ◽  
Enthalpy Change ◽  
Standard Free Energy Change ◽  
Standard Enthalpy Change ◽  
Low Activity

Summary For the purpose of understanding the swelling phenomenon of wood in liquids, the contributions of enthalpic and entropic terms to the standard free energy change of adsorption have been determined by measuring the temperature dependence of adsorption isotherms. The values of standard enthalpy change of adsorption are smaller for alcohols having both proton-accepting and -donating properties than for acetone having only a proton-accepting property. The results are discussed in terms of the proton-accepting power and the cohesive energy of the respective adsorbate liquids. Methanol showed a larger isosteric heat of adsorption to dried wood than to pre-swollen wood, and the amounts of methanol and acetone adsorbed on dried wood exceeded those on swollen wood within the low activity range. These results indicate the presence of more exothermic sites in dried wood than in pre-swollen wood, and of pre-existing spaces and/or parts loosely hydrogen-bonded between wood constituents in the cell walls of dried wood.

The Equilibrium and the Determination of D00 (H—CN)

1975 ◽  
Vol 53 (16) ◽  
pp. 2365-2370 ◽  
Author(s):  
Don Betowski ◽  
Gervase Mackay ◽  
John Payzant ◽  
Diethard Bohme
Keyword(s):  
Free Energy ◽  
Standard Enthalpy ◽  
Transfer Reaction ◽  
Standard Free Energy ◽  
Proton Transfer Reaction ◽  
Enthalpy Change ◽  
Standard Free Energy Change ◽  
Flowing Afterglow ◽  
Standard Enthalpy Change

The rate constants and equilibrium constant for the proton transfer reaction [Formula: see text] have been measured at 296 ± 2 K using the flowing afterglow technique: kforward = (2.9 ± 0.6) × 10−9 cm3molecule−1s−1, kreverse = (1.8 ± 0.4) × 10−10 cm3 molecule1 s−1, and K = 16 ± 2. The measured value of K corresponds to a standard free energy change, ΔG296°, of −1.6 ± 0.1 kcal mol−1 which provides values for the standard enthalpy change, ΔH298°= −1.0 ± 0.2 kcal mol−1, the bond dissociation energy, D00(H—CN) = 124 ± 2 kcal mol−1, and the proton affinity, p.a.(CN−) = 350 ± 1 kcal mol−1.

scholarly journals A method for investigating the effect of temperature on the 695 nm band of insoluble cytochrome c

1975 ◽  
Vol 149 (1) ◽  
pp. 169-177 ◽  
Author(s):  
T A Moore ◽  
C Greenwood
Keyword(s):  
Ionic Strength ◽  
Cytochrome C ◽  
Computer Analysis ◽  
Standard Enthalpy ◽  
Entropy Change ◽  
Enthalpy Change ◽  
Effect Of Temperature ◽  
Standard Entropy ◽  
Ferricytochrome C ◽  
Standard Enthalpy Change

A method is described for computer analysis of simple spectrophotometric changes in particulate systems, and this has been applied to the bleaching of the 695 nm band of insoluble ferricytochrome c by temperature. The results show that insolubilization has no effect on the standard enthalpy change but lowers the value for the standard entropy change. This effect appears to be independent of the concentration of the gel matrix to which the cytochrome c is bound, but dependent on the ionic strength of the surrounding solution.

Mass spectrometric study of the reaction of BF3 with B2O3; the identification and heat of formation of B2OF4

1970 ◽  
Vol 48 (16) ◽  
pp. 2484-2487 ◽  
Author(s):  
D. R. Bidinosti ◽  
L. L. Coatsworth
Keyword(s):  
Temperature Dependence ◽  
Equilibrium Constant ◽  
Flow Reactor ◽  
Mass Spectrometric Study ◽  
Heat Of Formation ◽  
Enthalpy Change ◽  
Mass Spectrometric ◽  
Molecular Flow ◽  
Spectrometric Study ◽  
Kcal Mole

The reaction of BF3 with B2O3 in a molecular flow reactor has been studied with a mass spectrometer. Over the temperature range 930–1300 K the reaction has been found to produce B2OF4 with the stoichiometry[Formula: see text]From the temperature dependence of the equilibrium constant the enthalpy change for this reaction was determined to be 18.5 ± 3 kcal/mole and ΔHf0 (B2OF4) calculated to be −454 ± 2 kcal/mole at 1100 K.

TEMPERATURE DEPENDENCE BEHAVIOR OF ELECTRICAL RESISTIVITY IN NOBLE METALS AT LOW TEMPERATURES

2014 ◽  
Vol 5 (3) ◽  
pp. 982-992 ◽  
Author(s):  
M AL-Jalali
Keyword(s):  
Experimental Data ◽  
Electrical Resistivity ◽  
Temperature Dependence ◽  
Concentration Dependence ◽  
Low Temperatures ◽  
Noble Metals ◽  
Phonon Scattering ◽  
Theoretical Models ◽  
Residual Resistivity ◽  
Electron Phonon Scattering

Resistivity temperature – dependence and residual resistivity concentration-dependence in pure noble metals(Cu, Ag, Au) have been studied at low temperatures. Dominations of electron – dislocation and impurity, electron-electron, and electron-phonon scattering were analyzed, contribution of these mechanisms to resistivity were discussed, taking into consideration existing theoretical models and available experimental data, where some new results and ideas were investigated.

TI/PIMC METHOD WITH THE TAKAHASHI–IMADA APPROXIMATION FOR THE EQUILIBRIUM CONSTANT OF THE O + HCl ⇌ OH + Cl REACTION

2013 ◽  
Vol 12 (04) ◽  
pp. 1350026 ◽  
Author(s):  
MARCIN BUCHOWIECKI
Keyword(s):  
Monte Carlo ◽  
Temperature Dependence ◽  
Equilibrium Constant ◽  
Path Integral ◽  
Thermodynamic Integration ◽  
Partition Functions ◽  
Integration Path ◽  
Path Integral Monte Carlo

The thermodynamic integration/path integral Monte Carlo (TI/PIMC) method of calculating the temperature dependence of the equilibrium constant quantum mechanically is applied to O + HCl ⇌ OH + Cl reaction. The method is based upon PIMC simulations for energies of the reactants and the products and subsequently on thermodynamic integration for the ratios of partition functions. PIMC calculations are performed with the primitive approximation (PA) and the Takahashi–Imada approximation (TIA).

93Nb Nuclear Spin-Spin Relaxation in the Low-Dimensional Antiferromagnet Fe0.25NbS2

2007 ◽  
Vol 62 (10-11) ◽  
pp. 627-632
Author(s):  
Noriaki Okubo
Keyword(s):  
Temperature Dependence ◽  
Spin Relaxation ◽  
Nuclear Spin ◽  
Low Temperatures ◽  
Fast Decay ◽  
Low Dimensional

93Nb nuclear spin-spin relaxation has been examined in the low-dimensional antiferromagnet Fe0.25NbS2 between 4.2 K and 300 K. The relaxation is characterized by two T2’s. The temperature dependence is discussed together with the origin of the disappearance of the fast decay at low temperatures.

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