Condensation Polymerisation — Structured Questions (Cambridge International A-Level Chemistry): Exam Questions

State the names of two classes of organic molecules that can take part in condensation polymerisation.

Draw the structural formula of the dicarboxylic acid with the molecular formula C₄H₆O₄. The carboxylic acid groups must be shown fully displayed.

Extract:

Draw the structural formula of the dicarboxylic acid with the molecular formula C4H6O4. The carboxylic acid groups must be shown fully displayed.

State the systematic name of the dicarboxylic acid in (b).

Extract:

Draw the structural formula of the dicarboxylic acid with the molecular formula C₄H₆O₄. The carboxylic acid groups must be shown fully displayed.

The structural formula of butanedioic acid is shown with two fully displayed carboxylic acid groups connected by a two-carbon chain.

Draw one repeat unit of the polymer formed when C₄H₆O₄ polymerises with 1,2-diaminoethane, H₂NCH₂CH₂NH₂. The newly formed linkage must be shown fully displayed.

The structure of a synthetic polyester is shown below.

Draw the structural formulae of the two monomers used to make this polyester.

Extract:

The structure of a synthetic polyester is shown below.

Draw the structural formulae of the two monomers used to make this polyester.

One of the monomers is benzene-1,4-dicarboxylic acid. State the systematic name of the other monomer.

Extract:

One of the monomers is benzene-1,4-dicarboxylic acid. State the systematic name of the other monomer.

The systematic name of the other monomer is: Ethane-1,2-diol

State the name of the other product formed during the reaction between the two monomers in (b).

Benzene-1,4-dicarboxylic acid will also react to form a polyamide.

Fig. 2.2 shows the structures of three molecules, R, S, and T.

State which of the molecules, R, S, or T, reacts with benzene-1,4-dicarboxylic acid to form a polyamide.

Valylalanine, shown in Fig. 1.1, is a dipeptide.

Fig. 1.1

Valylalanine is heated under reflux with dilute hydrochloric acid. Two organic products are formed.

Draw the structural formula of one of these organic products.

Fig. 1.2 shows a dipeptide synthesised from the amino acids cysteine and tryptophan.

Fig. 1.2

Draw the skeletal formula of the amino acid tryptophan.

Polyamides can form strong fibres suitable for weaving. Polyalkenes are generally too weak for this purpose.

Fig. 1.3 shows the structure of serine, an amino acid that forms polyamide links.

Fig. 1.3

Explain why polyamides are suitable for use as weaving fibres but polyalkenes are not. In your answer, refer to the intermolecular forces between the polymer chains.

Explain how the molecule NH₂CH₂CH₂COCl can undergo condensation polymerisation.

Polyurethanes are polymers made by the reaction of a diisocyanate with a diol, as shown in Fig. 2.1. R¹ and R² are hydrocarbon groups.

Fig. 2.1

Lycra^® in Fig. 2.2 is a polyurethane formed from the diisocyanate P and HOCH₂CH₂OH.

Fig. 2.2

i) State the molecular formula of diisocyanate P.

ii) Draw one repeat unit of Lycra^®. The newly formed linkages must be shown fully displayed.

Extract:

Lycra® in Fig. 2.2 is a polyurethane formed from the diisocyanate P and HOCH₂CH₂OH.

Polyurethanes are polymers made by the reaction of a diisocyanate with a diol, as shown in Fig. 2.1. R¹ and R² are hydrocarbon groups.

Fibres of Lycra^® are strong due to the intermolecular forces between the polymer chains. Complete the table to state two types of intermolecular force responsible for this property, and the groups involved.

State the name of one commercially important example of each of the following types of synthetic polymer.

Synthetic polyamide ..................................................................................................

Synthetic polyester ..................................................................................................

Fig. 2.3 shows the repeat unit of Nylon 66.

Fig. 2.3

Nylon 66 is heated under reflux with dilute sulfuric acid.

Draw the skeletal formulae of the two organic products formed.

Explain how ethane-1,2-diamine acts as a Brønsted–Lowry base.

Construct an equation to show the reaction of ethane-1,2-diamine with an excess of hydrochloric acid.

Ethane-1,2-diamine can react with ethanedioic acid, HOOCCOOH, to form a condensation polymer.

Draw the skeletal formula of the polymer, showing exactly two repeat units. The newly formed linkages must be shown fully displayed.

Fig. 1.1 shows a general dicarboxylic acid and a general diol.

Fig. 1.1

Draw one repeat unit of the polyester formed from these monomers. The newly formed linkage must be shown fully displayed.

In terms of n, state the number of molecules of water formed in the condensation polymerisation of n molecules of a dicarboxylic acid and n molecules of a diol.

Construct an equation for the condensation polymerisation of propanedioyl dichloride and butane-1,4-diol. Your equation should use structural formulae for the monomers and the repeat unit.

Extract:

Construct an equation for the condensation polymerisation of propanedioyl dichloride and butane-1,4-diol. Your equation should use structural formulae for the monomers and the repeat unit.

Propanedioyl dichloride has the structure ClCO–CH2–COCl, a three-carbon chain with an acyl chloride (–COCl) group at each end.

Butane-1,4-diol is HO–CH2CH2CH2CH2–OH: four carbons with –OH at each end.

State the systematic names of an alternative pair of monomers that could be used to produce the same polymer chain as in (c).

Monomer 1 ..................................................................................................

Monomer 2 ..................................................................................................

Lactic acid has the structural formula CH₃CHOHCOOH.

i) State the names of the two functional groups present in lactic acid.

ii) State the systematic name of lactic acid.

iii) State the type of stereoisomerism shown by lactic acid.

iv) Draw three-dimensional structures for the two stereoisomers of lactic acid.

Extract:

Lactic acid has the structural formula CH3CHOHCOOH.

Explain how lactic acid can undergo condensation polymerisation.

Extract:

Lactic acid has the structural formula CH3CHOHCOOH.

Poly(lactic acid) is a polyester.

i) Draw a section of the poly(lactic acid) chain showing exactly two repeat units. The newly formed ester linkages must be shown fully displayed.

ii) State whether the central carbon atom in the repeat unit remains a chiral centre in the polymer. Explain your answer.

Extract:

Lactic acid has the structural formula CH3CHOHCOOH.

Poly(lactic acid) can also be synthesised from a monomer containing an acyl chloride functional group.

Draw the skeletal formula of this alternative monomer.

State the systematic name of this monomer.

Nomex^® and Kevlar^® are two examples of polyamides containing benzene rings. Nomex^® is made from 1,3-diaminobenzene and benzene-1,3-dicarboxylic acid.

Draw the skeletal formulae of these two monomers.

Extract:

Nomex® and Kevlar® are two examples of polyamides containing benzene rings. Nomex® is made from 1,3-diaminobenzene and benzene-1,3-dicarboxylic acid.

Draw one repeat unit of the Nomex^® polymer. The newly formed linkages must be shown fully displayed.

Kevlar^® is made from 1,4-diaminobenzene and benzene-1,4-dicarboxylic acid.

Draw two adjacent polymer chains of Kevlar^®, each showing one repeat unit. Clearly show the strongest intermolecular force between the two chains.

Extract:

Nomex® and Kevlar® are two examples of polyamides containing benzene rings. Nomex® is made from 1,3-diaminobenzene and benzene-1,3-dicarboxylic acid.

The 1,3-substitution means the chain is angled (kinked) at each benzene ring, unlike the straight chain in Kevlar. Make sure the bonds come from the 1 and 3 positions, not from 1 and 4.

Kevlar® is made from 1,4-diaminobenzene and benzene-1,4-dicarboxylic acid.

State whether Kevlar^® or Nomex^® will have the higher melting point. Explain your answer in terms of the structure of the polymer chains.