Commercially available cold packs are simple in design: a pouch with water on one side, isolated by a barrier from a specific salt on the other side. When the barrier is broken, the salt and water mix and the solution turns cold. Select which of the statements is true about the reaction occurring in cold packs. O The reaction between the salt and water is endothermic. O The reaction between the salt and water is exothermic. O The reaction between the salt and water is neither endothermic nor exothermic. The cold pack releases heat into the environment. #8

The reaction between the salt and water is endothermic

Explanation:

An endothermic reaction is one that absorbs heat from the surrounding creating a kind of coldness in the immediate environment of the reaction. The direct opposite of endothermic reaction is exothermic reaction, a reaction that dissipates heat to the immediate surrounding of the reaction.

Commercial cold packs works based on the principle of endothermic reaction. The packs are usually made up of water and ammonium nitrate salts isolated by easily breakable barriers. The dissolution of ammonium nitrate salts in water is generally endothermic.

In order to make use of the cold pack, a force needs to be applied to the pack in order to break the barrier separating the water and the ammonium salt. The water-ammonium salt mixture creates an endothermic reaction which immediately lowers the temperature of the resulting solution to about 35 F for a period of 10 to 15 minutes.