15. Oxidise in this context means to react with oxygen.
16. Iron + oxygen → iron oxide
17. They might think their food could get contaminated with a non-edible/poisonous
substance.
18. If consumers cannot see the oxygen scavenger, they will not know it is there.
Consumers are used to seeing food wrapped in clear plastic and will not notice a
difference.
19. Retailers might like the packaging because it will help make the food last longer so
less will go past its ‘sell-by’ date before it is sold. This will reduce the retailer’s
waste and save money.
20. The new packaging might be more expensive than conventional packing.
Questions 21–24 require knowledge of polymers, their structure and function. If this
topic has not been covered, you may wish to direct students to leave these questions
out or remove them from the worksheet.
21. Polymer: a long chain molecule made of lots of small molecules (monomers)
joined together.
Side chain: a group of atoms sticking off/attached to the main polymer chain.
22. As the polymer warms up, the molecules move more and vibrate faster.
23. A polymer with long side chains needs more energy to move apart from the other
polymer molecules. This is because there are stronger intermolecular forces
holding the molecules with long side chains together so it will take more energy to
pull them apart.
146 Inspirational chemistry
24. Long side chains are likely to lead to a higher melting point as there are stronger
attractions between the polymer chains. The side-chained polymers move more as
the material warms up, leading to the opening of pores in the polymer film.
25. Supermarkets might want to use the labels to give consumers confidence in what
they are buying.
26. Various answers are possible here – students might answer ‘yes’ because the labels
would allow consumers to see if what they are buying is fresh or not; they might
answer ‘no’ because unscrupulous supermarkets could just change the labels.
27. Paragraph about students’ own reaction to the information. Mark by impression.