Energy transfer thermodynamic estimates

Thermodynamic estimates of the driving force for energy transfer, by either the Forster or Dexter mechanism, may be made from the following ... 

The first and second laws are concise statements of constraints that Nature imposes on energy transfers involved in any process. As such, they can be used in several ways to obtain quantitative information about processes that connect a given initial state to a given final state. A typical engineering question is to determine the amounts of Q and W needed for a proposed change of state. If the process path is known or can be reliably estimated, then Q and W may be computed directly, without recourse to the laws of thermodynamics. But in most situations, the process path is unknown and in fact unknowable then, our strategy would be to invoke the first and second laws, so that we may perform the analysis solely in terms of system-dependent state functions. Variations on this problem are also common for example, we may know an initial state and need to identify the final state that would result when known amounts of Q and W cross the boundary. 

The use of these expressions is effectual only in cases where there is no extensive deviation in the system behavior due to charge transfer overpotential or other kinetic effects.(l) The calculated threshold or thermodynamic energy requirement (2 ) (AG in the previous equation) is often much lower than actually encountered, but is still useful in estimating an approximate or theoretical minimum energy required for electrolysis. Part of the difficulty in applying thermodynamics to many systems of industrial interest may reside in an inability to properly define the activities or nature of the various species involved in the... 

Methanol and Water. Methanol and water mixtures have been a popular choice for workers interested in free energies of transfer of ions from water into a mixed solvent. Such mixtures exhibit a drop in dielectric constant with increasing methanol content. Hence the electrical term must be estimated in order to compare spectroscopic and thermodynamic quantities. Feakins and Voice (28) have presented new data and revised earlier data for the alkali metal chlorides. In advance of carefully determined and extrapolated emf data for fluorides, using the solid state fluoride selective electrode based on lanthanum fluoride, some data of moderate accuracy have been presented (27). On the... 

Upon electronic excitation the redox properties of either the electron donor (D) or the acceptor (A) are enhanced. The feasibility of an electron transfer can be estimated from a simple free reaction energy consideration as customary in the frame of the Rehm-Weller approach (Eq. (1)) [11], where Efy2 (P) and 4) represent the oxidation and reduction potential of the donor or the acceptor, respectively. AEexcit stands for the electronic excitation energy, whereas Aiscoui indicates the coulombic interaction energy of the products formed (most commonly radical ions). This simplified approach allows a first approximation on the feasibility of a PET process without considering the more complex kinetics as controlled by the Marcus theory [6c]. For exergonic processes (AG<0) a PET process becomes thermodynamically favorable. 

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