Question

The cold compress used in cold therapy has been shown to be greatly effective in reducing swelling by reducing the flow of blood and other fluids to the injured area. A cold compress is also beneficial in relieving the sensations of pain and restoring strength and mobility more quickly. The instant cold compress contains an inner bag of $N{H_4}N{O_3}$ and an outer bag of water. Explain the role of $N{H_4}N{O_3}$ in cold compress?

Answer 1

Hint : Cold compress is very effective at reducing swelling and numbing pain. An injury generally swells because fluid leaks from the blood vessels. Cold causes the vessels to constrict and reduce their tendency to ooze. If less fluid leaks from blood vessels, the swelling will be less.

Complete Step By Step Answer:
Cold helps in easing inflammation and muscle spasms which are the two common sources of pain. Cold compress used in cold therapy is very effective in treatments to ease pain and swelling from minor injuries. The sooner you apply cold compress to the injured area, the sooner it reduces the pain and swelling. The instant cold compress contains an inner bag of ammonium nitrate and an outer bag of water. The ammonium nitrate does not lose its nitrogen to the atmosphere. The dissolution of ammonium nitrate in water is endothermic. This makes ammonium nitrate the best choice of material in instant cold packs.

Note :
Many instant cold packs have ammonium nitrate in them. When ammonium nitrate is dissolved in water, it splits into positive ammonium ions and negative nitrate ions. In this dissolving process, the water molecules donate some of their energy and as a result of this, the water cools down. The instant cold packs are a replacement for crushed ice which is used as first aid on sport injuries and it can be carried as first aid in situations where ice is unavailable or not appropriate to use.