exothermic
Heat involves the transfer of thermal energy between two bodies that are at different temperatures. If you held a flask containing a reaction that releases energy, you would be able to feel the heat being transferred from the reaction into your hand. A process in which heat is released is referred to as exothermic . Conversely, reactions that absorb energy will remove energy from the surroundings, causing the container to feel cold. For example, dissolving ammonium nitrate in water will significantly lower the water temperature. Processes that absorb energy from their surroundings are called endothermic .