When is a reaction exothermic or endothermic

Consider, for example, a diagram that charts the energy change when a candle burns. Because more energy is released when the products are formed than is used to break up the reactants, this reaction is exothermic. Brittny All of this stuff relates to thermodynamics—the study of heat and its relationship to energy and work. Classifying a chemical reaction as exothermic or endothermic is simple. It comes down to weighing the energy needed to break bonds in the reactants with the energy released when the products are formed.

If you do not respond, everything you entered on this page will be lost and you will have to login again. Skip Navigation. Vimeo ID: Video Transcript. Energy is released when bonds are formed. Download Video Transcript. Sponsored by BP. This can be especially dangerous if the material reaches its flash point or autoignition temperature , at which point a fire or explosion could occur.

Therefore, it is very important to know when a chemical reaction can generate excess heat and to take appropriate measures to deal with this. Examples include slow mixing, using a cooling bath, or avoiding that reaction. Most mixtures of incompatible chemicals involve violently rapid exothermic reactions. See also : autoignition temperature , flash point , oxidation.

Additional definitions from Google and OneLook. Entry last updated: Monday, February 3, This page is copyright by ILPI. Unauthorized duplication or posting on other web sites is expressly prohibited. Send suggestions, comments, and new entry desires include the URL if applicable to us by email. Disclaimer : The information contained herein is believed to be true and accurate, however ILPI makes no guarantees concerning the veracity of any statement. Examples of exothermic reactions include:.

Everyday uses of exothermic reactions include self-heating cans and hand warmers. When energy is taken in from the surroundings, this is called an endothermic reaction and the temperature of the surroundings decreases.

Examples of endothermic reactions include:. Everyday uses of endothermic reactions include instant ice packs which can be used to treat sports injuries. The slideshow describes an exothermic reaction between dilute sodium hydroxide and hydrochloric acid and an endothermic reaction between sodium carbonate and ethanoic acid.