Thermodynamic affinity, definition

Wettability of a solid surface definition and assessment The concept of wettability of a solid by a liquid is directly related to the wetting processes. This concept is specially useful in the fields of detergency, lubrication or enhanced oil recovery. In the context of the oil industry, proposals were made by Briant and Cuiec (1972) for the experimental assessment of wettability, which was defined in terms of the thermodynamic affinity of a solid surface for a liquid. 

Note that the definition of electron affinity does not follow the usual thermodynamic convention in ihat a positive electron affinity is exothermic. See Chapter 2. 

Equations 27 and 28 permit a simple comparison to be made between the actual composition of a chemical system in a given state (degree of advancement) and the composition at the equilibrium state. If Q K, the affinity has a positive or negative value, indicating a thermodynamic tendency for spontaneous chemical reaction. Identifying conditions for spontaneous reaction and direction of a chemical reaction under given conditions is, of course, quite commonly applied to chemical thermodynamic principle (the inequality of the second law) in analytical chemistry, natural water chemistry, and chemical industry. Equality of Q and K indicates that the reaction is at chemical equilibrium. For each of several chemical reactions in a closed system there is a corresponding equilibrium constant, K, and reaction quotient, Q. The status of each of the independent reactions is subject to definition by Equations 26-28. 

Using a novel ligand one may conveniently calculate the difference in affinity, designated by AAG, based upon the actual precise measurement of two vital parameters viz., thermodynamic cycle, and affinity of the ligand, in a definite structure of an established drug-receptor complex. 

Note that all these abovementioned expressions for the standard affinity and the standard thermodynamic functions of micellisation were based on the definition of the CMC as an inflection point in the dependence ai(ctoti) given by Eqs. (5.53) and (5.54). If we use other definitions of the CMC, the corresponding relations will be different. 

The heats of adduct formation with many Lewis acids have been measured experimentally in the gas phase using the technique of ion cyclotron resonance [10]. The absolute proton affinity (PA) of a gaseous base molecule has a precise thermodynamic definition in relation to the negative of the enthalpy variation for a hypothetieal reaction of attachment of an isolated proton to a molecule M in the gas phase. 

The absolute proton affinity (PA) of a base molecule in the gas phase has a precise thermodynamic definition in relation to the enthalpy variation of the hypothetical reaction... 

The first non systematic introduction of thermodynamics in Chemical Kinetics is due to the second couple of scientists previously cited Augustus George Vernon Harcourt (1834-1919) and William Esson (1839-1916). Harcourt was an important chemist, member of the Royal society and president of Chemical society, Esson a mathematician and Savilian professor of Geometry. They worked at University of Oxford in a period particularly fruitful for Sciences in Britain. It is the peak of positivism and at the time different sciences, included chemistry, got clearly distinct university courses. Their activity covered a period of fifty years and represented the main passage from natural philosophy speculations to modern scientific reasoning. Influenced by Van t Hoff they will definitively abandon ambiguous terms like Affinity and Chemical Forces. 

A = A - A is the over-all affinity of the reaction, cf. (4.24). Quite a similar transformation is performed in the case of a diffusion 2-port such that by comparison of (7.39) or (7.41) with the definition of generalized thermodynamic forces and fluxes in (3.79) we eventually may write... 

Motion is explained by the Newtonian concept of force, but what is the driving force for chemical change Why do chemical reactions occur, and why do they stop at certain points Chemists called the force that caused chemical reactions affinity, but it lacked a clear definition. For the chemists who sought quantitative laws, a definition of affinity, as precise as Newton s definition of mechanical force, was a fundamental problem. In fact, this centuries-old concept had different interpretations at different times. It was through the work of the thermochemists and the application of the principles of thermodynamics as developed by the physicists, notes the chemistry historian Henry M. Leicester, that a quantitative evaluation of affinity forces was finally obtained [1, p. 203]. The thermodynamic formulation of affinity as we know it today is due to Theophile De Bonder (1872-1957), the founder of the Belgian school of thermodynamics. 

We have defined a thermodynamic state function for the linear system in (2.6, 2.5), and for the nonlinear system in (2.13, 2.12), in each case in terms of species-specific affinities and the kinetic rates in the forward and reverse reactions. (We labeled these state functions there with (j) and cj), respectively, but use here the common label cf)). With two definitions, one for the net rate of the reaction... 

---