An exothermic reaction is any chemical reaction that gives off energy, meanwhile, called chemical modification to the chemical process or chemical reaction in which two or more substances (reagents), by the action of a variable energy become in other substances called products; substances can be elements, or compounds failing. For example, iron oxide is the resulting chemical reaction after the reaction of oxygen in the air with the iron. The exothermic reaction occurs especially in those reactions of oxidation, which are chemical reactions in which there is an electronic transfer between the reagents, giving way to a modification of the oxidation of the mentioned States with respect to the products. I.e. an oxidation reaction occurs in the system in question must be an element that electrons and another that accepts them. Note that when the oxidation reaction is intense it may give way to the fire. Among the changes exothermic acquaintances include condensation, the transition from gaseous to liquid state and solidification, which is the transition from liquid to solid state. The most common example of exothermic reaction is combustion, releasing an enormous amount of light and heat. In combustion, we find ourselves with an element that is burning, which is the fuel and other combustion, it is that produces combustion; most of the time it's oxygen gas mode. Reaction which opposes the exothermic is the endothermic reaction in which, on the contrary, it's a chemical reaction that absorbs energy.
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