Endothermic and Exothermic

Every reaction also has an exchange of energy either endothermic or exothermic. Endothermic means the reaction takes in the energy around it. Exothermic means that energy is realeased by the reaction.


This is a graph of an Endothermic reaction.

This is an Exothermic reaction:

There is a very subtle difference between the two, in the endothermic the product has more energy than the reactants and in the exothermic reaction the product has less energy. Aside from the the same thing happens, enough energy is needed to get the reactant to the activated complex ( the activation energy) and then depending if the reaction is endothermic or exothermic energy is left in the product or given off. The difference of the energy in the product and the reactant is the ∆H  and is positive only if the reaction is endothermic and negative when the reaction is exothermic.

Also when writing up chemical reactions enegry can be included to show how the reaction works.

For example:

AB + 125kJ -> A + B