| Date | November 2019 | Marks available | 2 | Reference code | 19N.3.hl.TZ0.5 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Discuss | Question number | 5 | Adapted from | N/A |
Question
Kevlar® is used to make racing tires.
Draw the structure of the monomers of Kevlar® if the by-product of the condensation polymerization is hydrogen chloride.
State and explain why plasticizers are added to polymers.
Discuss why the recycling of plastics is an energy intensive process.
Markscheme
OR
H2NC6H4NH2 ✔
OR
Cl(O)CC6H4C(O)Cl ✔
increases flexibility/softness/plasticity ✔
break/weaken intermolecular forces/IMF/H-bonds «between chains» ✔
Any two of:
collection/transportation of plastic waste ✔
separation/sorting of different types «of plastic»
OR
separation/sorting of plastic from other materials ✔
melting plastic ✔
processing/washing/cleaning/drying/manufacture of recycled plastic ✔
Examiners report
Syllabus sections
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18M.3.sl.TZ2.4b.i:
State the chemical reason why plastics do not degrade easily.
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19M.3.sl.TZ1.4c(ii):
The trace quantities of dioxins from tyre fires are rarely inhaled and instead settle on the ground.
Describe why this is a health concern.
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19M.3.sl.TZ2.5e:
Suggest why the addition of plasticizers is controversial.
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19M.3.hl.TZ2.5d:
Suggest why the addition of plasticizers is controversial.
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17N.3.sl.TZ0.7b.ii:
One of the two infrared (IR) spectra is that of polyethene and the other of polytetrafluoroethene (PTFE).
Deduce, with a reason, which spectrum is that of PTFE. Infrared data is given in section 26 of the data booklet.
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17N.3.sl.TZ0.7c:
Many plastics used to be incinerated. Deduce an equation for the complete combustion of two repeating units of PVC, (–C2H3Cl–)2.
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18N.3.sl.TZ0.2d:
Repeating units of several polymers are listed.
The infrared (IR) spectrum of one of these polymers is shown.
Deduce, giving a reason, the name of this polymer and its Resin Identification Code (RIC), using sections 26 and 30 in the data booklet.
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18N.3.sl.TZ0.2b.ii:
In an incomplete combustion of the polyvinyl chloride, PVC, it was found that hydrogen chloride, carbon monoxide, carbon dioxide, and water vapour were released.
Formulate an equation for this reaction using the formula of the PVC repeating unit.
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18M.3.sl.TZ1.4d:
Suggest two of the major obstacles, other than collection and economic factors, which have to be overcome in plastic recycling.
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18M.3.sl.TZ2.4b.ii:
Compare two ways in which recycling differs from reusing plastics.
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19M.3.hl.TZ1.4c:
Tyre fires emit trace quantities of polychlorinated dibenzofurans and polychlorinated dibenzo-p-dioxin.
Outline, using section 31 of the data booklet, why polychlorinated dibenzofuran is not classed chemically as a dioxin but considered “dioxin-like”.
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19M.3.sl.TZ2.5c:
Identify a hazardous product of the incineration of polychloroethene.
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19M.3.sl.TZ1.4c(i):
Tyre fires emit trace quantities of polychlorinated dibenzofurans and polychlorinated dibenzo-p-dioxin.
Outline, using section 31 of the data booklet, why polychlorinated dibenzofuran is not classed chemically as a dioxin but considered “dioxin-like”.
