Lesson 18B.3

18B.3 Polyamides and amino acids Quiz: Pearson Edexcel Chemistry, Unit 18

20 questions

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Lesson 18B.3, Polyamides and amino acids: 20 multiple choice questions for the Pearson Edexcel Chemistry (9CH0), Unit 18: Organic Chemistry III, written with Revision Ninja.

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The 20 questions

  1. What type of polymerisation forms a polyamide from a diacid and a diamine?

    • Free-radical polymerisation initiated by peroxides, with each monomer adding across a double bond
    • Ring-opening polymerisation with no by-product, in which a cyclic amide opens to join the chain
    • Addition polymerisation with no atoms lost as each monomer unit joins the growing chain
    • Condensation polymerisation, with water eliminated at each amide link

  2. What is the repeat unit of nylon-6,6?

    • -[NH(CH2)6NH-CO(CH2)4CO]-
    • -[CO(CH2)6CO]-
    • -[NH(CH2)6CO]-
    • -[NH(CH2)4NH(CH2)4CO]-

  3. Which monomers are used to make nylon-6,6?

    • Hexanedioic acid and hexane-1,6-diol
    • Ethanoic acid and hexane-1,6-diamine
    • Hexanedioic acid and hexane-1,6-diamine
    • Hexane-1,6-diamine and hexane-1,6-diol

  4. What is the zwitterion of an amino acid?

    • A form with the carboxylic acid protonated and the amine neutral, which is the dominant form in strong base
    • A neutral molecule with a double bond between nitrogen and carbon, which forms when the amine reacts with the acid
    • A form with both groups carrying a negative charge, which is the dominant form in strongly alkaline solution
    • A form with the amine protonated and the carboxylic acid deprotonated, giving both a positive and a negative charge

  5. Which functional groups are present in 2-aminopropanoic acid?

    • A nitrile group and a carbonyl group
    • Two carboxylic acid groups and no amine group
    • An amine group, -NH2, and a carboxylic acid group, -COOH
    • An amide group and a hydroxyl group

  6. Which bond links amino acid units in a protein?

    • The disulfide link, -S-S-, formed by oxidation of thiol groups
    • The ether link, -O-, formed by loss of a hydrogen atom
    • The peptide bond, an amide link -CONH- formed by condensation
    • The ester link, -COO-, formed with loss of water

  7. Calculate the relative molecular mass of the repeat unit of nylon-6,6, C12H22N2O2, using Ar: C 12, H 1, N 14, O 16.

    • 228
    • 226
    • 114
    • 198

  8. Calculate the relative molecular mass of alanine, C3H7NO2, using Ar: C 12, H 1, N 14, O 16.

    • 73
    • 87
    • 91
    • 89

  9. Which of these is a diamine?

    • Hexanedioic acid
    • Hexane-1,6-diamine
    • Hexane-1,6-diol
    • Hexanal

  10. A dipeptide forms from glycine and alanine. How many water molecules are eliminated?

    • 2
    • 3
    • 1
    • 0

  11. At the isoelectric point, what is the net charge of an amino acid?

    • Plus one
    • Plus two
    • Minus one
    • Zero

  12. Which technique is used to separate the amino acids produced by hydrolysis of a protein?

    • Paper or thin-layer chromatography, comparing Rf values with standards
    • Mass spectrometry, comparing molecular ion peaks only
    • Titration with sodium hydroxide, comparing endpoints
    • Infrared spectroscopy, comparing carbonyl stretching frequencies only

  13. Water is eliminated when a polyamide forms from acid and amine groups. If HCl rather than water is lost from an acyl chloride and amine, what is the mass of HCl per mole of amide link?

    • 44.0 g
    • 17.0 g
    • 36.5 g
    • 18.0 g

  14. Which polymer contains amide links in its backbone?

    • Poly(propene)
    • Nylon-6,6
    • Poly(ethylene terephthalate)
    • Poly(ethene)

  15. How many peptide links are present in a tripeptide?

    • 3
    • 4
    • 1
    • 2

  16. Why do amino acids have high melting temperatures?

    • They exist as zwitterions with strong ionic attractions between molecules, so much energy is needed to melt them
    • They are gases at room temperature, so they need extra heat to melt and then boil in a second stage
    • They form many covalent bonds between molecules, which are hard to break and so raise the melting temperature
    • They are non-polar with strong London forces that need high temperatures to overcome in the solid state

  17. An amino acid solution has a pH below its isoelectric point. Which species dominates?

    • The anion, with the carboxylic acid deprotonated and the amine neutral
    • The neutral zwitterion with no net charge
    • The dianion, with both groups deprotonated
    • The cation, with the amine group protonated and the carboxylic acid neutral

  18. Why are most amino acids optically active, while glycine is not?

    • Most contain an ionic group that absorbs polarised light, but glycine contains no ionic group at all
    • Most have a chiral alpha carbon bonded to four different groups, but glycine has two hydrogen atoms on that carbon
    • Most have a double bond that rotates polarised light, but glycine has no double bond in its structure
    • Most are racemic mixtures that show no rotation, but glycine is a pure single enantiomer that rotates light

  19. Why is nylon-6,6 strong?

    • Ionic bonds between carboxylate groups on neighbouring chains
    • Hydrogen bonding between the amide links on neighbouring chains
    • Dipole-dipole forces only, as the chains contain no hydrogen
    • Covalent cross-links formed by the amine groups

  20. Which product is formed when a diacid and diamine condense to make a polyamide?

    • Carbon dioxide, released at each amide link formed
    • Nitrogen gas, released at each amide link formed
    • Water, released at each amide link formed
    • Hydrogen gas, released at each amide link formed

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