What is equilibrium

Introduction What is Equilibrium Concepts of frustrated Equilibrium... 

What is equilibrium constant Which factors affect the equilibrium constant ... 

What is equilibrium film pressure What is its physical signi ficance ... 

The course of a surface reaction can in principle be followed directly with the use of various surface spectroscopic techniques plus equipment allowing the rapid transfer of the surface from reaction to high-vacuum conditions see Campbell [232]. More often, however, the experimental observables are the changes with time of the concentrations of reactants and products in the gas phase. The rate law in terms of surface concentrations might be called the true rate law and the one analogous to that for a homogeneous system. What is observed, however, is an apparent rate law giving the dependence of the rate on the various gas pressures. The true and the apparent rate laws can be related if one assumes that adsorption equilibrium is rapid compared to the surface reaction. 

However, there is a much more profound prior issue concerning anliannonic nonnal modes. The existence of the nonnal vibrational modes, involving the collective motion of all the atoms in the molecule as illustrated for H2O in figure A1.2.4 was predicated on the basis of the existence of a hannonic potential. But if the potential is not exactly hannonic, as is the case everywhere except right at the equilibrium configuration, are there still collective nonnal modes And if so, since they caimot be hannonic, what is their nature and their relation to the hannonic modes ... 

In calculations of pore size from the Type IV isotherm by use of the Kelvin equation, the region of the isotherm involved is the hysteresis loop, since it is here that capillary condensation is occurring. Consequently there are two values of relative pressure for a given uptake, and the question presents itself as to what is the significance of each of the two values of r which would result from insertion of the two different values of relative pressure into Equation (3.20). Any answer to this question calls for a discussion of the origin of hysteresis, and this must be based on actual models of pore shape, since a purely thermodynamic approach cannot account for two positions of apparent equilibrium. 

What is the effect on the solubility of AgCl if HNO3 is added to the equilibrium solution defined by reaction 6.29 ... 

The equilibrium constant for an acid-base indicator is determined by preparing three solutions, each of which has a total indicator concentration of 1.35 X lQ-5 M. The pH of the first solution is adjusted until it is acidic enough to ensure that only the acid form of the indicator is present, yielding an absorbance of 0.673. The absorbance of the second solution, whose pH was adjusted to give only the base form of the indicator, was measured at 0.118. The pH of the third solution was adjusted to 4.17 and had an absorbance of 0.439. What is the acidity constant for the acid-base indicator ... 

In discussing Fig. 4.1 we noted that the apparent location of Tg is dependent on the time allowed for the specific volume measurements. Volume contractions occur for a long time below Tg The lower the temperature, the longer it takes to reach an equilibrium volume. It is the equilibrium volume which should be used in the representation summarized by Fig. 4.15. In actual practice, what is often done is to allow a convenient and standardized time between changing the temperature and reading the volume. Instead of directly tackling the rate of collapse of free volume, we shall approach this subject empirically, using a property which we have previously described in terms of free volume, namely, viscosity. 

Whenever you have to report on the structure of an alloy - because it is a possible design choice, or because it has mysteriously failed in service - the first thing you should do is reach for its phase diagram. It tells you what, at equilibrium, the constitution of the alloy should be. The real constitution may not be the equilibrium one, but the equilibrium constitution gives a base line from which other non-equilibrium constitutions can be inferred. 

Suppose you take two flasks, one containing pure water and the other a buffer solution maintained at a pH of 7.0. If you add 0.1 mole of acetic acid to each one and the final volume in each flask is 1 L, how much acetic acid is present at equilibrium How much acetate ion In other words, what is the extent of ionization of acetic acid in an unbuffered medium and in a buffered one ... 

The free-energy change of the glycogen phosphorylase reaction is AG° = +3.1 kj/mol. If [P ] = 1 mM, what is the concentration of glncose-1-P when this reaction is at equilibrium ... 

A prediction of AE /AEq to within 0.1 kcal/mol may produce a AG /AGq accurate to maybe 0.2 kcal/mol. This corresponds to a factor of 1.4 error (at T = 300 K) in the rate/equilibrium constant, which is poor compared to what is routinely obtained by experimental techniques. Calculating AG /AGq to within 1 kcal/mol is still only possible for fairly small systems. This corresponds to predicting the absolute rate constant, or the equilibrium distribution, to within a factor of... 

Whereas only a few atomie jumps may be neeessary to enable ehanges in the equilibrium degree of SRO, without atomie movement over long distanees ehanges in LRO may not be suffieient to reaeh equilibrium. This ean lead to a eompetition between inerease of SRO in the matrix and formation of the new LR0-phase when lowering the temperature below an order/disorder phase boundary. In those cases, thermal and/or meehanieal pretreatment of the sample is of erueial importanee for what is observed in the sample. 

What is the equilibrium pressure of hydrogen sulfide if those of hydrogen and sulfur gases are 0.103 atm and 0.417 atm, respectively ... 

At a certain temperature, K is 0.040 for the decomposition of two moles of bromine chloride gas (BrCl) to its elements. An equilibrium mixture at this temperature contains bromine and chlorine gases at equal partial pressures of0.0493 atm. What is the equilibrium partial pressure of bromine chloride ... 

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