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CHEMISTRY, M7 2024 HSC 14 MC

Glycine, an amino acid, can react with itself or other amino acid monomers to form silk, a natural polymer.

Glycine has the structure:
 

       

A section of silk polymer is shown.
 

Which monomer could react with glycine to form this section of silk polymer?
 
 

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\(B\)

Show Worked Solution

→ The silk polymer shown is a condensation polymer and also a polyamide formed from monomers containing the amine and carboxylic functional groups.

→ During the formation of the polymer, the \(\ce{NH2}\) amine group will lose a hydrogen and that hydrogen will form a water molecule with the hydroxyl group.

→ The part of glycine that remains in the polymer is \(\ce{NHCH2CO}\).

→ The second repeating unit in the polymer is \(\ce{NHCHCH3CO}\).
 

\(\Rightarrow B\)

CHEMISTRY, M7 2016 VCE 12 MC

A condensation reaction involving 200 glucose molecules, \(\ce{C6H12O6}\), results in a polysaccharide. The molar mass, in g mol\(^{-1}\), of the polysaccharide is

  1. 36 000
  2. 35 982
  3. 32 418
  4. 32 400
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\(C\)

Show Worked Solution

→ 200 \(\ce{C6H12O6}\) molecules react to form a polysaccharide

→ 199 \(\ce{H2O}\) molecules are released in this condensation polymerisation

\(\ce{MM(C6H12O6) = 180.0\ \text{g mol}^{-1} }\)

\(\ce{MM(H2O) = 18.0\ \text{g mol}^{-1} }\)

\(\ce{MM(\text{polysaccharide})}\) \(= 200 \times 180.0-199 \times 18.0\)  
  \(= 32\ 418\ \text{g mol}^{-1}\)  

 
\(\Rightarrow C\)

CHEMISTRY, M7 EQ-Bank 27

Contrast ONE addition polymer and ONE condensation polymer in terms of their structures, properties and uses. Include structural formulae in your answers.   (7 marks)

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Addition polymer – polyethylene. Condensation polymer – nylon.

Structures

→ Polyethylene is made by the addition of ethylene monomers with the following structural formula:

→ Nylon is a condensation polymer made from 1,6-diaminohexane and adipic acid, producing a by-product of water molecules. It has the following structural formula.

Properties

→ Polyethylene is inexpensive, weatherproof and relatively resistant to chemicals.

→ There are two main types of polyethylene which have different properties. Low-density polyethylene (LDPE) is semi-rigid while high density polyethylene (HDPE) is fluid.

→ Nylon is strong and relatively resistant to moisture absorptivity. It is longer lasting than polyethylene, resistant to chemicals and is used to make nylon fibre.

Applications

→ LDPE is used to produce products such as plastic soft drink bottles, flexible water pipes and cling wrap. HDPE’s fluidity make it an appropriate material for producing shopping bags, plastic crates and drums for storage.

→ Nylon is very versatile in its manufacturing uses. It is a common input for clothing, can be used for injection-moulded parts for vehicles and also as reinforcement for rubber tyres. 

→ Nylon is also used as the main material input for nylon thread which has a myriad of uses, including stitching for clothes and the production of rope.

Show Worked Solution

Addition polymer – polyethylene. Condensation polymer – nylon.

Structures

→ Polyethylene is made by the addition of ethylene monomers with the following structural formula:

→ Nylon is a condensation polymer made from 1,6-diaminohexane and adipic acid, producing a by-product of water molecules. It has the following structural formula.

Properties

→ Polyethylene is inexpensive, weatherproof and relatively resistant to chemicals.

→ There are two main types of polyethylene which have different properties. Low-density polyethylene (LDPE) is semi-rigid while high density polyethylene (HDPE) is fluid.

→ Nylon is strong and relatively resistant to moisture absorptivity. It is longer lasting than polyethylene, resistant to chemicals and is used to make nylon fibre.

Applications

→ LDPE is used to produce products such as plastic soft drink bottles, flexible water pipes and cling wrap. HDPE’s fluidity make it an appropriate material for producing shopping bags, plastic crates and drums for storage.

→ Nylon is very versatile in its manufacturing uses. It is a common input for clothing, can be used for injection-moulded parts for vehicles and also as reinforcement for rubber tyres. 

→ Nylon is also used as the main material input for nylon thread which has a myriad of uses, including stitching for clothes and the production of rope.

CHEMISTRY, M7 2020 HSC 12 MC

The structure of part of a polymer chain is shown.
 


 

Which statement best explains why plastics made from this polymer require a temperature of approximately 250°C before they begin to soften?

  1. The carbon–carbon bonds in the polymer chains are strong.
  2. The carbon–hydrogen bonds in the polymer chains are strong.
  3. Extensive dipole–dipole and dispersion forces exist between the polymer chains.
  4. Extensive hydrogen bonds and dispersion forces exist between the polymer chains.
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`C`

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→ The polymer diagram shows the following intermolecular forces: dipole-dipole forces and dispersion forces.

→ High temperatures break some of the intermolecular forces, causing the plastic to soften (polyesters can’t form `text{H}`-bonds).

`=> C`

CHEMISTRY, M7 2022 HSC 18 MC

A low molecular weight biopolymer is being investigated for its suitability for medical use. In one trial a molecular weight of `2900 pm 100\ text{g}\ text{mol}^(-1)` proved to be optimum.

A section of this biopolymer is shown.
 

Which will produce the suitable biopolymer?
 

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`D`

Show Worked Solution

This polymer is a condensation polymer, meaning that it is formed through the reaction between monomers that consist of a carboxylic acid and/or an alcohol functional group, with the elimination of water.

Thus, if `text{n}` monomers react to form this polyester, `text{(n – 1)}` molecules of water would be eliminated.

Calculating their molar masses:

`text{n}\ xx\ text{monomers}` `= text{polymer} + text{(n – 1)} xx text{H}_2 text{O}`
`text{n} xx (90.078)` `= 2900 + text{(n – 1)} xx (18.016)`
`text{n}(90.078-18.016)` `=2900-18.016`
`:.\ text{n}` `=2881.984/72.062`
  `=39.99…`

`=> D`


♦♦ Mean mark 23%.

CHEMISTRY, M7 2021 HSC 10 MC

The structure of part of a polymer chain is shown.
 

 
Which is the monomer of this polymer?
 

 

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`B`

Show Worked Solution

→ The polymer formed is a condensation polymer, where the by-product is water (`text{H}_2 text{O}`).

→ From the polymer shown, the alcohol functional group must ie on the second carbon atom, and the carboxylic functional group must lie on the first carbon atom.

→ Thus, could only be formed from monomer B.

`=> B`