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QLDChemistryQuick questions
Unit 4: Structure, synthesis and design
Quick questions on Condensation polymers and biomolecules (QCE Chemistry Unit 4)
12short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is difference from addition polymerisation?Show answer
QCAA test items frequently ask you to classify a polymer or biopolymer as addition or condensation; the cleanest discriminator is whether a small molecule is eliminated.
What is polyesters?Show answer
PET (polyethylene terephthalate) is the polyester of ethane-1,2-diol (ethylene glycol) and benzene-1,4-dicarboxylic acid (terephthalic acid).
What is polyamides?Show answer
Nylon-6,6 is the polyamide of 1,6-diaminohexane (hexamethylenediamine) and hexanedioic acid (adipic acid). The "6,6" refers to the six carbons in each monomer.
What is biomolecules?Show answer
The same condensation chemistry assembles all three major biomolecules in the QCAA syllabus.
What is hydrolysis (the reverse reaction)?Show answer
Every condensation polymer can be hydrolysed back to its monomers by reacting with water under acid or enzyme catalysis. Hydrolysis is the chemistry of digestion and of the saponification of fats. QCAA EA may ask you to predict the hydrolysis products of a given polyester, polyamide or biomolecule; the products are simply the starting monomers, with water added back.
What is properties from condensation polymer structure?Show answer
Three main factors set bulk properties:
What is common traps?Show answer
Forgetting the eliminated molecule. Condensation always loses a small molecule. Drawing a polymer without it gives an unbalanced equation.
What is forgetting the eliminated molecule?Show answer
Condensation always loses a small molecule. Drawing a polymer without it gives an unbalanced equation.
What is drawing only one bond formed?Show answer
A polymer arises because each monomer is difunctional and bonds extend on both sides. Show the repeat unit with bonds exiting on both ends.
What is confusing amide and ester linkages?Show answer
Amide is -CO-NH- (carbonyl + nitrogen). Ester is -CO-O- (carbonyl + oxygen). Different reactivity, different IMF, different polymer.
What is treating proteins as addition polymers?Show answer
Amino acids do not have a C=C double bond; they polymerise by condensation, eliminating water. The same is true for carbohydrates and triglycerides.
What is forgetting that triglyceride hydrolysis under base gives soap?Show answer
Soap is the sodium or potassium salt of a fatty acid, formed by saponification of triglycerides. QCAA IA3 contexts on soap manufacture build on this.