INDEX Gibbs free energy

Temperature, Heat capacity. Pressure, Dielectric constant. Density, Boiling point. Viscosity, Concentration, Refractive index. Enthalpy, Entropy, Gibbs free energy. Molar enthalpy. Chemical potential. Molality, Volume, Mass, Specific heat. No. of moles. Free energy per mole. 

State functions derivable therefrom (such as ASd or AHd) are the fundamental quantities of interest, the arbitrariness of K or Kq causes no difficulty other than being a nuisance. It should be remembered that, once a choice of units and of standard state has been made, a value of /C or 1 implies that AG is a large negative quantity, and hence, that AGd is also likely to be large and negative. Thus, equilibrium will be established after the pertinent reaction has proceeded nearly to completion in the direction as written. Conversely, for values of K, or Kq equilibrium sets in when the reaction is close to completion in the opposite direction. Thus, the equilibrium constant serves as an index of how far and in what direction a reaction will proceed, and this prediction does not depend on the arbitrariness discussed earlier. It should be clear that the equilibrium constants do not in themselves possess the same fundamental importance as the differential Gibbs free energies. However, the full utility of equilibrium constants will not become clear until some illustrative examples are provided below. 

The Universal Quasi-chemical Theory or UNIQUAC method of Abrams and Prausnitz divides the excess Gibbs free energy into two parts. The dominant entropic contribution is described by a combinatorial part ( ). Intermolecular forces responsible for the enthalpy of mixing are described by a residual part ( ). The sizes and shapes of the molecule determine the combinatorial part, which is thus dependent on the compositions and requires only pure component data. Since the residual part depends on the intermolecular forces, two adjustable binary parameters are used to better describe the intermolecular forces. As the UNIQUAC equations are about as simple for multi-component solutions as for binary solutions, the UNIQUAC equations for multicomponent solutions are given below. Species are identified by subscript i, subscript j is a dummy index. Here, is a relative molecular surface area and r, is a relative molecular volume. Both of these quantities are pure-species parameters. 

Understand the relationships among Gibbs free energy, chemical potential, reaction quotients (Q), the equilibrium constant, and the saturation index SI). 

E = constant in scaling equation G = Gibbs free energy h = scaling function defined by Equation 8 M = molecular weight n = index of refraction P = pressure... 

Adiabatic temperature rise values were obtained in this study as a index of thermal hazard prediction of MEKPO. Feasible reactions at every MEKPO decomposition steps were identified from the possible reaction clusters by obtaining Gibbs free energy of reaction. And for each feasible reaction, enthalpy of reaction, heat capacity values and adiabatic temperature rise were assessed. Thermal inertia and MEKPO mixture composition ratio were considered. Adiabatic temperature rise values for each reaction condition were easily obtained, and by this, it is shown that this approach in this study can be a good methodology to get both qualitative and quantitative risk assessment result for hazardous undesirable reaction. The results were compared with the experimental and simulation data from the reference, and the errors were less than reasonable range. 

The Gibbs free energy is mostly used to describe chemical processes because the usual laboratory situation corresponds to constant p and T. Using (4.1.23) the irreversible evolution of G to its minimum value can be related to the affinities of the reactions and the reaction velocities d t /dt (in which the index k identifies different reactions)... 

A crystal is surrounded at equilibrii n by flat, atomically smooth, low-index faces or, in Frank s classification, by singular faces. These faces in equilibrium forms are defined by the Gibbs definition of the equilibrium form requiring a minimum of the surface free energy of the crystal at constant volume (see Section 5.1). 

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