Addition and Condensation Polymers · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

How plastic chains join and split again

Science · Chemistry · ages 17-18
Name ______________________   Date ____________

  1. In an addition polymer, what small molecule is lost as the chain grows?

    • One water at each link
    • One carbon dioxide at each link
    • None at all

  2. When ethene monomers join into a chain, what happens to each double bond?

    • One bond opens so each carbon links to a neighbour
    • Both carbons drop every bond they hold
    • A water molecule leaves each monomer

  3. A diacid joins a diol to start a polyester. What leaves at each new link?

    • Nothing at all
    • One water molecule
    • One ethene molecule

  4. Why does boiling in water break a polyester but not polythene?

    • Polythene melts before water can touch it
    • Ester links split with water, alkene links do not
    • Water adds new double bonds to polythene

  5. A chain segment reads CH2 CH2 CH2 CH2. Which monomer built it?

    • Methane
    • Water
    • Ethene

  6. A short polyester forms 4 links, losing one water at each link. How many water molecules leave in total?

    Answer: ______________

  7. A polyamide melts higher than polythene. Which link between chains best explains it?

    • Hydrogen bonds between polyamide chains
    • Broken double bonds in polythene
    • Water trapped inside the polyamide

  8. A student claims an old polythene bag can be boiled back into ethene. What is wrong?

    • Bags are too big to fit the pot
    • Boiling adds carbon to the chain
    • Polythene links have no water joint to split
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Answer key

For grown-ups. Fold this page away before handing over the rest.

How plastic chains join and split again W1-mt_klu208vTI1-s1

  1. None at all · Addition uses only atoms the monomers already had, so nothing is lost.
  2. One bond opens so each carbon links to a neighbour · Only an opened double bond gives each carbon a free link to its neighbour.
  3. One water molecule · Every ester link in a polyester forms with one water squeezed out.
  4. Ester links split with water, alkene links do not · Only the ester joint has a reverse reaction with water.
  5. Ethene · Reading the repeat back gives ethene, the alkene with the same atoms.
  6. 4 · Four links times one water per link gives 4.
  7. Hydrogen bonds between polyamide chains · Stronger attractions between chains need more heat to pull apart.
  8. Polythene links have no water joint to split · Hydrolysis needs the joint that condensation made, which polythene lacks.
Worksheet · LightMySky