Identify the two functional groups that react together to form the ester linkage between monomers in the PET polymer

PET polymer or Polyethylene terephthalate is also known as Terylene. In the PET polymer, the ester linkage between the monomers is formed by the reaction of the OH group of ethylene diol (glycol) and the CO2H group of terephthalic acid.

In the family of polyester, PET is considered as the mostly used thermoplastic polymer resin.

It is used widely in clothing fibers, as liquid and food containers, and as a substance for engineering resins. In the United Kingdom it is known as terelyne, in the United States as Dacron, and in Russia as Lavsan.

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.