Endothermic and Exothermic Reactions
An endothermic reaction lowers temperature in flask so that the flask will freeze and stick to a wet piece of wood. An endothermic reaction is used in drug store instant cold pack. An exothermic reaction in a Styrofoam cup will significantly raise the temperature in the cup.
Some chemical reactions absorb heat from the surroundings, resulting in a cooling of the surroundings (Endothermic Reactions). Some chemical reactions evolve heat, resulting in a warming of the surroundings (Exothermic Reactions).