Chemical reaction energy potential

Chemical reaction has potential for both efficient energy conversion and storage. This part shows possibility of efficient thermal energy storage and thermal energy conversion methodologies by chemical reaction. 

Since the whole theme of this book is concerned with unexpected or concealed sources of energy, it is relevant to reiterate that compressed gases may contain a large content of kinetic energy over and above that potentially available from chemical reaction energy possibilities for the gas. A procedure for calculating available kinetic energy from rupture of compressed gas containers is found in... 

In a chemical reaction, energy can neither be created nor destroyed but can interconvert between potential and kinetic forms. 

PROBLEM In a chemical reaction the potential energy of the reactants is 40 kJ/mol, the potential energy of the products is 15 kJ/mol, and the activation energy is 25 kJ/mol. Find the potential energy of the activated complex and the heat of reaction. 

Figure 1. Compound Morse potentials of the form employed by Tsai and Trevino [1-3] to simulate energy release arising from chemical reaction. Energy and bond length are in arbitrary units.

The protons and the neutrons in atomic nuclei are bound together with forces that are much greater than the forces that bind atoms together to form molecules. In fact, the energies associated with nuclear processes are more than a million times those associated with chemical reactions. This potentially makes the nucleus a very attractive source of energy. 

It is known that the potential energy varies as the reaction occurs and presents an energy barrier which should be surpassed for the occurrence of the reaction. Starting from the different energy levels of the reactants and products, which characterizes the transformation reaction enthalpy of a chemical reaction, the potential energy curve varies according to Figure 3.3. 

Chemical Reaction Energy Type Potentially Remarks Critical Processing Parameters ... 

To proceed fiirther, to evaluate the standard free energy AG , we need infonnation (experimental or theoretical) about the particular reaction. One source of infonnation is the equilibrium constant for a chemical reaction involving gases. Previous sections have shown how the chemical potential for a species in a gaseous mixture or in a dilute solution (and the corresponding activities) can be defined and measured. Thus, if one can detennine (by some kind of analysis)... 

The above discussion represents a necessarily brief simnnary of the aspects of chemical reaction dynamics. The theoretical focus of tliis field is concerned with the development of accurate potential energy surfaces and the calculation of scattering dynamics on these surfaces. Experimentally, much effort has been devoted to developing complementary asymptotic techniques for product characterization and frequency- and time-resolved teclmiques to study transition-state spectroscopy and dynamics. It is instructive to see what can be accomplished with all of these capabilities. Of all the benclunark reactions mentioned in section A3.7.2. the reaction F + H2 —> HE + H represents the best example of how theory and experiment can converge to yield a fairly complete picture of the dynamics of a chemical reaction. Thus, the remainder of this chapter focuses on this reaction as a case study in reaction dynamics. 

A number of different experimental methods may be used to energize the unimolecular reactant A. For example, energization can take place by the potential energy release in chemical reaction, i.e. 

Chemical reaction dynamics is an attempt to understand chemical reactions at tire level of individual quantum states. Much work has been done on isolated molecules in molecular beams, but it is unlikely tliat tliis infonnation can be used to understand condensed phase chemistry at tire same level [8]. In a batli, tire reacting solute s potential energy surface is altered by botli dynamic and static effects. The static effect is characterized by a potential of mean force. The dynamical effects are characterized by tire force-correlation fimction or tire frequency-dependent friction [8]. 

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