Athletic trainers use instant ice packs that can be cooled quickly on demand. squeezing the pack breaks an inner container, allowing two components to mix and react. this reaction makes the pack become cold. describe the heat flow for this spontaneous process.

The heat flow is  best described as an exchange of heat between the system and the surroundings.

Explanation:

Heat is a form of energy which is transferred spontaneously from a hotter body to a cool body as a result of temperature differences between the substances. In the problem , it can be said that heat moves from  the surroundings which may be a fractured knee of the athlete to the ice packs.  

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.