For the most effective hot pack, the temperature change should be <u>positive</u>.
<em>Hot packs are generally utilized for their heat-producing abilities. Hence, the reactions leading to the activation of hot packs are usually exothermic, that is, heat energy generating. In other words, positive or increased temperatures must be generated when hot packs are activated.</em>
This is unlike cold packs which are utilized for the cold-generating abilities. Reactions leading to their activations must be endothermic, that is, heat-absorbing.
Neutrons keep the Protons "in check", meaning Protons hold a very strong repulsive positive charge. The Neutrons counteract the repulsive force within a small space to keep the Nucleus stable.
