Question

A soccer coach keeps a couple of instant cold packs in her bag in case one of her players suffers a muscle injury. Instant cold packs are composed of a plastic bag containing a smaller water bag and solid ammonium nitrate. In order to activate the fold pack, the bag is kneaded until the smaller water bag breaks, which allows the released water to dissolve the ammonium nitrate. Which of the following statements about the dissolution of ammonium nitrate in water is correct?

a) It is an exothermic process
b) It is an endothermic process
c) It is a reversible process
d) It is a spontaneous process

Answer 1

The dissolution of ammonium nitrate in water is an endothermic process that absorbs heat from the surroundings.

Step-by-step explanation:

The correct statement about the dissolution of ammonium nitrate in water is that it is an endothermic process.

When solid ammonium nitrate dissolves in water, it absorbs heat from the surroundings, making the solution cold. This is why ammonium nitrate is used in instant cold packs to provide a cold compress for treating injuries and reducing swelling.

Endothermic dissolutions, like the dissolution of ammonium nitrate, require a greater energy input to separate the solute species than is recovered when the solutes are solvated. However, they are still spontaneous due to the increase in disorder that accompanies the formation of the solution.