When an athlete gets hurt they apply sometimes an instant cold pack to the injury. the instant cold pack works by mixing two chemicals that create a chemical reaction. what evidence is there that a chemical reaction is taking place in the cold pack?

The evidence showing that there is a chemical reaction taking place is the instantaneous temperature drop once the cold pack is shaken.

Explanation:

When an athlete applies a cold pack to the injury, they shake it before, mixing the water and ammonium-nitrate fertilizer inside the cold pack. This mixing is an endothermic reaction, which means it absorbs heat. In turn, the temperature falls to 35 F for around 10 minutes.