An environmentally-conscious student is breaking the rings from a six-pack drink holder before disposing of it. This reduces the
potential for the six-pack ring to ensnare wildlife and cause ecological harm. In breaking the rings, the student notices that the plastic rings heat up. What argument supports that this is an exothermic chemical reaction?
Firstly we need to remember what exothermic reaction is in thermodynamics. exothermic reaction describes a process or reaction that releases energy from the system to its surroundings, usually in the form of heat, but also in a form of light, sound, or electricity.
In this scenario, due to the heating up nature noticed by the ring during breaking shows that energy is being released to the surrounding in the form of heat which suggest it being an exothermic reaction.
An element with a valence of 8 are most likely noble gases (He, Ne, Ar, etc) which means they're already stable so they dont need to undergo chemical bonds with another atom because they already have a full valence shell.
