Question

Many first aid kits include an instant cold pack. A cold pack utilizes a chemical reaction that has a significant change in energy in order to make the pack feel cold. Explain which type of reaction, an endothermic reaction or an exothermic reaction, would be most useful for making a cold pack.

Answer 1

The reaction that absorb the heat from the environment is called endothermic and release the heat to the environment during the reaction is called exothermic.

The macking of cold pack is an endothermic reaction. An endothermic reaction would be most useful for the making a cold pack.

Many instant cold packs function by dissolving a salt into water. As the salt disassociates, heat is either released in an absorbed in an endothermic reaction. Commercial instant cold packs typically use either ammonium nitrate or urea as their salt component. This reaction happen in a similar manner. When the salt is dissolved in water, the ionic bonds of the salt separate. This process requires energy, which is obtained from the surroundings. The ions then form bonds with the water, a process that releases energy. If more energy is released than taken in, then the process is exothermic, making the solution feel warmer. If more energy is taken in than released, then the process is endothermic, making the solution feel cooler.