Exothermic Reaction Essay

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CHEMICAL REACTIONS EXOTHERMIC REACTIONS: When one substance is brought together or mixed with another and the resulting interaction evolves or generates heat, the process is referred to as an exothermic reaction. An exothermic (exo- is a prefix meaning "out of") reaction is one where the energy flows out of the system into the environment. Combustion reactions are exothermic. Some exothermic reactions may require heating just to get started, and will then proceed on their own. Exothermic reactions pose special hazards whether occurring in the open environment or within a closed container. In the open, the heat evolved will raise the temperature of the reactants, of any products of the reaction, and of surrounding materials. Since several properties of all substances are a function of temperature, such as pressure, the resulting higher temperatures may affect how the materials involved behave in the environment. Heat will increase the vapor pressures of hazardous materials and the rate at which they vaporize. If very high temperatures are achieved, nearby combustible materials may ignite. Explosive materials, whether they are the reactants of the reaction or just nearby, may explode upon ignition or excessive heating. Similar hazards are associated with exothermic reactions taking place in closed containers. In this case, however, increasing internal temperatures as well as the evolution of gases from the reaction may increase internal pressures to the point that the tank or container ruptures violently in an over-pressurization explosion, thus suddenly releasing large amounts of possibly flammable and/or toxic gases or vapors into the atmosphere. Such gases or vapors may also be released through ruptured pipes, opened relief valves or devices, or any other paths to the external environment. REACTIONS WITH WATER OR AIR Some of the most basic types of exothermic

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