Final answer:
Chemical cold packs, also known as ice packs, use an endothermic reaction to produce cold temperatures.
Step-by-step explanation:
Chemical cold packs, also known as ice packs, use a process called endothermic reaction to produce cold temperatures. When a chemical inside the pack reacts with water, it absorbs heat energy from its surroundings, causing the pack to cool down. Ammonium nitrate is commonly used in cold packs and its dissolution in water is an endothermic process. The reaction can be represented by the equation:
NH4NO3(s) + H2O(l) → NH4NO3(aq) + Heat
An instant cold pack is a single-use device that consists of two bags; one containing water, inside a bag containing ammonium nitrate, calcium ammonium nitrate or urea. When the inner bag of water is broken by squeezing the package, it dissolves the solid in an endothermic process.
These are filled with water and a chemical reactor. When the bag is squeezed, the water interacts with the chemical to start a reaction that lowers the temperature of the water to almost freezing.