Question Video: Identifying the Structure of Poly(Ethylene Terephthalate) | Nagwa Question Video: Identifying the Structure of Poly(Ethylene Terephthalate) | Nagwa

Question Video: Identifying the Structure of Poly(Ethylene Terephthalate) Chemistry • Third Year of Secondary School

Poly(ethylene terephthalate) is a condensation polymer that can be made from ethylene glycol and terephthalic acid molecules. The following figure shows the structures of the ethylene glycol and terephthalic acid molecules. What is the structure of the poly(ethylene terephthalate) condensation polymer?

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Video Transcript

Polyethylene terephthalate is a condensation polymer that can be made from ethylene glycol and terephthalic acid molecules. The following figure shows the structures of the ethylene glycol and terephthalic acid molecules. What is the structure of the polyethylene terephthalate condensation polymer?

Before we can determine the structure of polyethylene terephthalate, we’ll need to clear some space. So let’s remove the answer choices for now. Polyethylene terephthalate is a polymer. A polymer is a chemical that can be formed from similar chemical units called monomers that join together. More specifically, polyethylene terephthalate is a condensation polymer. A condensation polymer is a type of polymer that forms when bits of the monomers break off and the remainders bond together. So the formation of a condensation polymer is accompanied by the formation of small by-product molecules.

We are told in the question that polyethylene terephthalate can be made from ethylene glycol and terephthalic acid molecules. So polyethylene terephthalate is a copolymer, a polymer produced from two or more different monomers. When terephthalic acid and ethylene glycol react, the terephthalic acid monomer loses a hydroxy group. The ethylene glycol monomer loses a hydrogen atom. The two monomer pieces join together using an ester linkage, and the byproduct water is produced. The end of each monomer can go on to react further. The monomers can continue to react increasing the length of the polymer.

Looking at the polymer, we can see that the same unit will repeat over and over in the polymer chain. We can represent the structure of a polymer by writing the repeating unit in brackets followed by a subscript letter 𝑛. The 𝑛 indicates the number of times the unit repeats in the polymer, which can vary and is often a very large number.

Now that we know the structure of polyethylene terephthalate, we can bring back the answer choices. We can see that the correct structure of the condensation polymer polyethylene terephthalate is the structure shown in answer choice (B).

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