Endothermic reaction
|
|
In chemistry, an endothermic reaction is one in which the products have less energy than the reactants. An amount of energy called the activation energy is always required to break the bonds in the reactants, but in this case, more energy is released when the chemicals recombine into the products of the reaction. In other words, less energy is required to break the bonds of the reactants than is given off as they recombine into the products. Endothermic reactions are often described as reactions that "feel cold". Heat energy from the material surrounding the reactants is usually what breaks their bonds, so as heat energy is transferred from the surroundings to the reactants, the surroundings get colder. This is often summarized in a chemical equation as follows:
- Reactants + Energy → Products
Example: The reactants of a particular chemical reaction are dissolved in a solvent. If the solution in which the reaction is taking place cools off (loses heat energy), the reaction must have been endothermic.
Note: When using a calorimeter, the change in heat energy of the calorimeter is equal to the opposite of the change in heat of the system.
An endothermic reaction is the opposite of an exothermic reaction.
Template:Chem-stubde:Endotherm et:Endotermiline reaktsioon fi:Endoterminen reaktio