Chemical bonding energy

The adsorption of nonelectrolytes at the solid-solution interface may be viewed in terms of two somewhat different physical pictures. In the first, the adsorption is confined to a monolayer next to the surface, with the implication that succeeding layers are virtually normal bulk solution. The picture is similar to that for the chemisorption of gases (see Chapter XVIII) and arises under the assumption that solute-solid interactions decay very rapidly with distance. Unlike the chemisorption of gases, however, the heat of adsorption from solution is usually small it is more comparable with heats of solution than with chemical bond energies. 

The flash lamp teclmology first used to photolyse samples has since been superseded by successive generations of increasingly faster pulsed laser teclmologies, leading to a time resolution for optical perturbation metliods tliat now extends to femtoseconds. This time scale approaches tlie ultimate limit on time resolution (At) available to flash photolysis studies, tlie limit imposed by chemical bond energies (AA) tlirough tlie uncertainty principle, AAAt > 2/j. 

Next, there is present, within the molecule, chemical energy which is related to the forces which hold the atoms together in the molecule. This is referred to as chemical bond energy. 

If, now, we continue warming the substance sufficiently, we will reach a point at which the kinetic energies in vibration, rotation, and translation become comparable to chemical bond energies. Then molecules begin to disintegrate. This is the reason that only the very simplest molecules—diatomic molecules—are found in the Sun. There the temperature is so high (6000°K at the surface) that more complex molecules cannot survive. 

Dynein, kinesin, and myosin are motor proteins with ATPase activity that convert the chemical bond energy released by ATP hydrolysis into mechanical work. Each motor molecule reacts cyclically with a polymerized cytoskeletal filament in this chemomechanical transduction process. The motor protein first binds to the filament and then undergoes a conformational change that produces an increment of movement, known as the power stroke. The motor protein then releases its hold on the filament before reattaching at a new site to begin another cycle. Events in the mechanical cycle are believed to depend on intermediate steps in the ATPase cycle. Cytoplasmic dynein and kinesin walk (albeit in opposite... 

A detailed calculation would be very difficult, but classical arguments are used to arrive at an approximation. The chemical bond energy is hard to guess, but it is noted that it saturates quickly with n, so that it can mostly be treated as an additive parameter (at least when n l). The change in the electrostatic energy is simply taken as the difference in the potential energy of a sphere of radius a (size of A+) and that of a sphere of radius b (cluster size) in a medium of dielectric constant K. This energy also saturates—that is, tends to a finite... 

Typical chemical bonds used to formulate energetic materials are C-NOj, N-NOj, O-NO2, N-N, and 0-0 bonds. When such bonds are broken in molecules due to thermal decomposibon or reactions with other molecules, molecules of the gases CO2 and N2 are formed, as shown in Fig. 2.1. The difference between the bond energy of the energetic material and that of the gas molecules is released as heat energy. The chemical bond energies of typical bonds found in molecules related to combustion are shown in Table 2.1.11-3]... 

Table 2.1 Chemical bond energies of the constituent bonds of energetic materials.

When reactant R of an energetic material reacts to generate product P, heat is released (or absorbed). Since the chemical bond energy of R is different from that of P, the energy difference between R and P appears as heat. The rearrangement of the molecular structure of R changes the chemical potential. The heat of reaction at... 

The heats of formation, AHy, are dependent on the chemical structures and chemical bond energies of the constituent molecules of the reactants and products. Equation (2.2) indicates that the higher the value of AHyu for the reactants and the lower the value of AHj p for the products, the higher the H xp that will be obtained. 

Atoms are held together in molecules by chemical bonds. Energy is required to break these bonds. The energy that is consumed to break one mole of a covalent bond in a molecule in the gaseous state is known as Bond Energy. 

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