Chemical reactions endothermic

Exothermic chemical reactions Endothermic processes pressure Material handling and transfer Enclosed or indoor process units Access relief pressure Drainage and spill control Toxic materials Sub-atmospheric Operation in or near flammable range Dust explosion... 

FIGURE 2.15 Time dependence of endothermic heat related to an irreversible chemical reaction. Endothermic heat of pads soaked in pH 4, pH 11 buffer solutions, slurries, and DIW was measured using MDSC. 

Endothermic process A process that adsorbs energy. Examples Endothermic chemical reaction Endothermic phase change. See also Exothermic process. 

Reactive scattering or a chemical reaction is characterized by a rearrangement of the component particles within the collision system, thereby resulting in a change of the physical and chemical identity of the original collision reactants A + B into different collision products C + D. Total mass is conserved. The reaction is exothemiic when rel(CD) > (AB) and is endothermic when rel(CD) < (AB). A threshold energy is required for the endothemiic reaction. 

Most chemical reactions are exothermic. In the few endothermic reactions that are known, heat is absorbed into the reaction product or products, which are known as endothermic or energy-rich compounds. Such compounds are thermodynamically unstable because heat woiild be released on decomposition of their elements. The majority of endothermic compounds possess a tendency toward insta-bihty and possibly explosive decomposition under various circumstances of initiation. 

Most chemical reactions are greatly affected by temperature. The previous chapters discussed reactions at isothermal condition, however, industrial reactors often operate under non-isothermal condition. This is because chemical reactions strongly depend on temperature, either absorbing (i.e., endothermic) or generating (i.e., exothermic) a large amount of heat. 

We next consider the synthesis and chemical reactions of the oxides of chlorine. Because the compounds are strongly endothermic and have large positive free energies of formation it is not possible to prepare them by direct reaction of CI2 and O2. Dichlorine monoxide, CI2O, is best obtained by treating freshly prepared yellow HgO and CI2 gas (diluted with dry air or by dissolution in CCI4) ... 

In addition to molecular geometry, the most important quantity to come out of molecular modeling is the energy. Energy can be used to reveal which of several isomers is most stable, to determine whether a particular chemical reaction will have a thermodynamic driving force (an exothermic reaction) or be thermodynamically uphill (an endothermic reaction), and to ascertain how fast a reaction is likely to proceed. Other molecular properties, such as the dipole moment, are also important, but the energy plays a special role. 

Exothermic reaction The temperature rise resulting from the liberation of heat by a chemical reaction. It is the opposite of endothermic reaction. 

A process that releases heat into the surroundings is called an exothermic process. Most common chemical reactions—and all combustions, such as those that power transport and heating—are exothermic (Fig. 6.8). Less familiar are chemical reactions that absorb heat from the surroundings. A process that absorbs heat is called an endothermic process (Fig. 6.9). A number of common physical processes are endothermic. For instance, vaporization is endothermic, because heat must be supplied to drive molecules of a liquid apart from one another. The dissolution of ammonium nitrate in water is endothermic in fact, this process is used in instant cold packs for sports injuries. 

Like CVD, PVD is a vapor deposition process where the deposition species are atoms, molecules, or a combination of the two. The distinction between these two processes is that, in CVD, deposition occurs by chemical reaction, whereas in PVD, deposition is by condensation. CVD is usually endothermic and PVD is exothermic. 

Heats of Reaction. Chemical reactions absorb or liberate energy, usually in the form of heat. The heat of reaction, h.Hn, is defined as the amount of energy absorbed or liberated if the reaction goes to completion at a fixed temperature and pressure. When > 0, energy is absorbed and the reaction is said to be endothermic. When /sHr < 0, energy is liberated and the reaction is said to be exothermic. The magnitude of Is.Hr depends on the temperature and pressure of the reaction and on the phases (e.g., gas, liquid, solid) of the various components. It also depends on an arbitrary constant multiplier in the stoichiometric equation. 

Prior to the chemical reaction of the silane with the silanol-groups on the sUica surface, the silane molecule has to make contact with the sUica surface by adsorption. Then the chemical reaction of silica with an alkoxy-silyl moiety of the coupling agent takes place in a two-step, endothermic reaction. The primary step is the reaction of alkoxy-groups with silanol-groups on the silica filler surface [4]. Two possible mechanisms are reported ... 

Most of the chemical reactions in the process industry are temperature dependent. They are either exothermic or endothermic. As a consequence, it is often necessary to remove the heat generated by an exothermic reaction to control the reaction temperature and to avoid thermal runaway reactions or to suppress endothermic by-product reactions, for instance [8]. 

ENDOTHERMIC REACTION A Chemical reaction resulting in absorption of heat. 

A chemical reaction may occur under conditions in which temperature is held constant, such as in the human body or a thermostatted automobile engine. The exothermicity or endothermicity of the reaction generates a heat flow, even though the temperature is constant. 

Endothermic reaction A chemical reaction that absorbs heat from its surroundings. 

Explain why it would not be practical to air-condition a home or business by using an endothermic chemical reaction. 

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