Hydrogen, dissociation

Butler D A and Hayden B E 1995 The indirect channel to hydrogen dissociation on W(100)c(2 2)Cu—evidence for a dynamical precursor Chem. Phys. Lett. 232 542... 

That is, hydrogen dissociates in the presence of the catalyst, forming hydrogen ions and giving up electrons to the anode. The hydrogen ions are transported across the membrane to the cathode. At the cathode, hydrogen ions react with oxygen to form H2O. 

It is common knowledge that, in the case of the hydrogen molecule studied in a minimal basis set, the correlation error can be explained by the existence of ionic species in the hydrogen dissociation products ... 

Okada, M., Ogura, S., Dino, W.A., Wilde, M., Flikutani, K. and Kasai, T. (2005) Reactivity of gold thin films grown on iridium Hydrogen dissociation. Applied Catalysis A General, 291, 55-61. 

At elevated temperatures, molecular hydrogen dissociates into the atomic form, which can readily enter and diffuse through the steel. Under these conditions, the diffusion of hydrogen in steel is more rapid. As discussed in Section 4, Forms of High Temperature Hydrogen Attack, hydrogen may react with the carbon in the steel to cause either surface decarburization or... 

An alternative approach by Zhu et al. (1990) yielded a similar activation energy (for P), while providing new information on the donor-hydrogen dissociation reaction. With electrical measurements they studied the electric-field induced migration of hydrogen that is thermally released from PH... 

Steiner and Rideal45 determined the Arrhenius parameters for (22), log k22 = 10.86 — 5200/4.58 T, from a study of the HCl-catalysed ortho-para hydrogen reaction in the temperature range 600-770°. When allowance is made for the better data for the hydrogen dissociation available to Steiner and Rideal, their results agree well with earlier work by Rodebush and Klingelhoefer46. 

The H2 + l)2 equilibration reaction was much faster than the diene hydrogenation, so that the rate-limiting step is not the hydrogen dissociation. The Pt behaves as a bifunctional... 

Basically, only thermal, not photolytic, mechanisms are considered. The dissociation energy of hydrogen is less than that of oxygen, so the initiation can be related to hydrogen dissociation. Only a few radicals are required to initiate the explosion in the region of temperature of interest, that is, about 675 K. If hydrogen dissociation is the chain s initiating step, it proceeds by the reaction... 

The hydrogen dissociation energy ) [Equation (15)] amounts to 3.1 kcal mor [TZ(3dl/,lp) CCSD(T) + ZPVE + BSSE], which is much less than for GeH (10 kcal mor ). 

The acidity of a C-H bond is influenced by the hybridization state of the carbon atom attached to the acidic hydrogen. Dissociation of the acid generates an anion whose lone pair of electrons is held in a hybridized orbital. We can consider sp orbitals to have more s character than sp orbitals, and similarly sp orbitals to have more character than sp orbitals (see Section 2.6.2). Since orbitals are closer to the nucleus than p orbitals, it follows that electrons in an p-hybridized orbital are held closer to the nucleus than those in an sp orbital those in an sp orbital are similarly closer to the nucleus than those in an sp orbital. It is more favourable for the electrons to be held close to the positively charged nucleus, and thus an p-hybridized anion is more stable than an p -hydridized anion, which is more stable than an p -hybridized anion. Thus, the acidity of a C-H bond decreases as the character of the bond decreases. 

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