Energy hydrogen fluoride

Another near resonant process is important in the hydrogen fluoride laser, equation (A3.13.37), where vibrational to vibrational energy transfer is of interest ... 

The bond dissociation energy of the hydrogen-fluorine bond in HF is so great that the above equilibrium lies to the left and hydrogen fluoride is a weak acid in dilute aqueous solution. In more concentrated solution, however, a second equilibrium reaction becomes important with the fluoride ion forming the complex ion HFJ. The relevant equilibria are ... 

It is known that the order of acidity of hydrogen halides (HX, where X = F, Cl, Br, I) in the gas phase can be successfully predicted by quantum chemical considerations, namely, F < Cl < Br < I. However, in aqueous solution, whereas hydrogen chloride, bromide, and iodide completely dissociate in aqueous solutions, hydrogen fluoride shows a small dissociation constant. This phenomenon is explained by studying free energy changes associated with the chemical equilibrium HX + H2O + HjO in the solu-... 

The last example represents a fairly rare elimination of hydrogen fluoride in preference to hydrogen chloride, a reaction that deserves a more detailed discussion A comparison of bond dissociation energies of carbon-halogen bonds shows that the carbon-fluorine bond is much stronger than the carbon-chlorine, carbon-bromine, and carbon-iodme bonds 108-116, 83 5, 70, and 56 kcal/mol, respec-... 

The following table lists the predicted bond energy of hydrogen fluoride computed with various methods using the 6-311-H-G(3df,3pd) basis set. We chose this basis set because it is near the basis set limit for this problem errors that remain can be assumed to arise from the method itself and not from the basis set. 

Add the energies of propane and fluorine atom (at left (the reactants), and then the energies of 1-propyl radica (or 2-propyl radical) and hydrogen fluoride (th( products). Are these reactions exothermic or endothermic If the former, then calculate the relative concentrations 0 1-propyl radical and 2-propyl radical that would exist ii an equilibrium mixture at 298 K. Use equation (1). 

Hydrogen abstraction reactions potential surfaces for, 25-26,26,41 resonance structures for, 24 Hydrogen atom, 2 Hydrogen bonds, 169,184 Hydrogen fluoride, 19-20, 20,22-23 Hydrogen molecules, 15-18 energy of, 11,16,17 Hamiltonian for, 4,15-16 induced dipoles, 75,125 lithium ion effect on, 12... 

Hirata and Iwata, 1998, extended these studies to linear oligomers and an infinite linear hydrogen fluoride polymer. Also this study substantiates the applicability of the BLYP and B3LYP functionals, for which reasonable agreement with experiment has been found with respect to structure, binding energies and vibrational frequencies of the species explored. 

Another important question deals with the intramolecular and unimolecular dynamics of the X-—RY and XR -Y- complexes. The interaction between the ion and molecule in these complexes is weak, similar to the intermolecular interactions for van der Waals molecules with hydrogen-bonding interactions like the hydrogen fluoride and water dimers.16 There are only small changes in the structure and vibrational frequencies of the RY and RX molecules when they form the ion-dipole complexes. In the complex, the vibrational frequencies of the intramolecular modes of the molecule are much higher than are the vibrational frequencies of the intermolecular modes, which are formed when the ion and molecule associate. This is illustrated in Table 1, where the vibrational frequencies for CH3C1 and the Cr-CHjCl complex are compared. Because of the disparity between the frequencies for the intermolecular and intramolecular modes, intramolecular vibrational energy redistribution (IVR) between these two types of modes may be slow in the ion-dipole complex.16... 

Hummer, John J., John M. Googin, Ph.D, Michael W. Knazovich, Paul R. Wasilko, and Janice West, 1992. "Report of Investigation of Accidental Release of Hydrogen Fluoride from the Y-12 Plant Oak Ridge, Tennessee, January 24, 1992," Martin Marietta Energy Systems, Inc., Oak Ridge, TN, March 1992. 

In fluorine thermochemistry, two key heat values frequently occur. They are the dissociation energy of difluorine, required for evaluation of fluorine bond energies and the heat of formation of hydrogen fluoride, a product in hydrolysis, hydrogenation, fluorine combustion, or neutralization reactions. These values have been difficult to measure and have changed considerably over the years. A recommended set of values has been reported in recent CODATA bulletins (60) which are collected in Table I together with older values and corrections to update them. 

Various fluorinations, which need principally much energy for the generation of the reagent fluorine, are carried out electrochemically in liquid hydrogen fluoride, even in an industrial scale [66]. Owing to the extreme toxicity and the corrosive medium, special precautions are necessary. 

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