Syntactic and Syndiotactic are NOT Synonymous

 

Question 20 from paper 1 of the QCAA chemistry exam 2022 is shown below. Can you answer it?

 

 You can if you make a couple of assumptions first:

1/ The 3D structure isn't given, so you have to assume (given the possible answers) that methyl groups above the chain are in fact coming out of the plane, while methyl groups below the chain are behind the plane.

2/ You have to assume that "syntactic" is a misprint of "syndiotactic" since there was no mention of this being a composite material.

Then you can choose (A) as the answer, and according to the answer sheet you would be correct.

 

However, here is an excerpt from the draft new Queensland Chemistry syllabus (for implementation in 2025 I believe),

      "Describe the structure features of

           -polyethene (LDPE and HDPE), polypropene (syntactic, isotactic and atactic) and                                             polytetrafluorethene."

(Cross my heart, this is what is says, the syllabus writers seem to have difficulties with adjectives as well as chemical nomenclature, where are the round brackets around tetrafluoroethene?)

 

So, it appears that students will study tacticity of polymers but only isotactic and atactic not syndiotactic, then they will look at composite materials in the form of syntactic foams.

Really?

 

Dear Queensland Chemistry syllabus and exam writers, the 3D structure of a polymer results in an isotactic, syndiotactic or atactic polymer.

A syntactic foam refers to a composite material in which hollow spheres are bound together by a polymer.