Chemical potential of hydrogen

Photosystem II Inhibitors. The PSII complex usually is assumed to be that stmctural entity capable of light absorption, water oxidation, plastoquiaone reduction, and generation of transmembrane charge asymmetry and the chemical potential of hydrogen ions (41). The typical PSII complex... 

An incidental conclusion discussed in Section 5 is that exposure of freshly etched silicon surfaces to a given ambient of plasma products seems always to produce a chemical potential of hydrogen just beneath the surface that varies only modestly (no more than a factor ten) over a wide range of the bulk donor or acceptor doping. 

The chemical potential of hydrogen in the gas phase, at equilibrium with the dissolved hydrogen in the solid, is given by Equation 2 where gh2 is the standard (1 atm) chemical potential of gaseous hydrogen. At small hydrogen concentrations in the metal, mh is given by Equation 3, (II, 25) where the next-... 

In electrochemistry we make it a rule that the standard chemical potential ju. of hydrogen ions is set zero as the level of reference for the chemical potentials of all other hydrated ions. The standard chemical potentials of various hydrated ions tabulated in electrochemical handbooks are thus relative to the standard chemical potential of hydrogen ions at unit activity in aqueous solutions. Table 9.3 shows the numerical values of the standard chemical potential, the standard partial molar enthalpy h°, and the standard partial molar entropy. 5 ,° for a few of hydrated ions. 

However, //(H ) is not a very convenient independent variable because it is a function of both the temperature and the concentration of hydrogen ions. The differential of the chemical potential of hydrogen ions is given by... 

Some individuals have advocated reporting of acidity of body fluids in terms of hydrogen ion concentration instead of pH. Their rationale is that pH is a measure of the chemical potential of hydrogen ions rather than a measure of the concentration of the ions,. Because chemical potential is a function of the activity coefficient, which is not known with certainty, the antilog of pH cannot be assumed to equal the hydrogen ion concentration. pH values should be treated as primary variables and reported as measured. 

Table I. Tee Change of Chemical Potential of Hydrogen Gas on Dilution With Nitrogen...

As indicated they are concentration cells, without liquid junctions, containing mixtures of electrolytes. Since the electrodes of the two halfcells are reversible to the chloride and hydrogen ions, the operation of such a cell involves per faraday of current the removal of one mol of hydrogen chloride from one of the two solutions and the reappearance of the same amount in the other, the mechanism being exactly that described for cell (22) of Chapter 6. The potential of the cell is therefore a measure of the difference of the chemical potential of hydrogen chloride in the two solutions, according to the equation ... 

A promoter zone, in which the adsorbed promoter increases the chemical potential of hydrogen sufficiently to significantly impact the reaction kinetics... 

The chemical potential of hydrogen is defined with respect to Ph2- < —0.6 eV implies that no hydrogen is present. The chemical potential of HgS is determined with respect to the chemical potential of S in MoSg. A/xs = 0 implies a high HgS partial pressure. 

Flere the following notation is used, cl and cj atomic concentration at interstitial or trap sites i and iQ molar chemical potential of hydrogen within the binary mixture hydrogen/steel and the temperature-depending, pure substance contribution at reference pressure p = 0 p = Tr(ff/3) hydrostatic stresses (pressure) Vn molar volume of FI in solid solution M = cMI mobility of H with M = D/ d i/dc) = D/(RT), (D diffusion coefficient) R = 8.314 J/mol K universal gas constant and J diffusion flux of FI. 

Let fi be the chemical potential of hydrogen chloride in the vapour phase. For equilibrium with the solution... 

However, energetic preference of clusters versus monovacancies does not necessarily mean more abundance of the former. To illustrate these, grand-canonical probabilities were calculated using Equation. 11.24. The chemical potential of hydrogen in the hydride is assumed to be identical to the potential per atom in the gas phase (equilibrium condition) ... 

The chemical potential of hydrogen is the energy required to move a hydrogen atom from inHnity into the lattice. Let O be the total stress tensor, H the expansion tensor of one hydrogen atom, Cq the volumetric concentration (mol m ) in the initial reference state, and C the concentration in the current state. The primary cause for the elastic interaction between hydrogen and hydrostatic stress Helds is a Hrst-order dilatation-al interaction, which gives rise to the chem-... 

The two electrodes are connected to a voltmeter (a), or to an external resistive load (b), or to an external power source (c). As long as the chemical potential of hydrogen is different at the two sides (electrodes) of the cell, a driving force for hydrogen transport across the PCM exists and the cell may operate in one of the following modes [29] ... 

Such effects lead to modified solubilities of components (or for charged particles to modified surface charges) in stressed solids. One example that has been considered in some detail in the literature is hydrogen solubility in metals or alloys In iron, in which hydrogen is mobile in the interstitial lattice, the chemical potential of hydrogen is adequately decreased by applying tensile stress and increased by applying compressive stress [6,107]. 

For a proton-electron transfer reaction, a computational standard hydrogen electrode potential can be used directly. To do this, we take advantage of the equivalence of the chemical potential of hydrogen gas and the proton-electron... 

---