Fig. 1 shows a section of poly(ethene) film used to wrap freshly picked apples. The long chain has been drawn with only three repeat units. The packing comp...
Question 1 Report
Fig. 1 shows a section of poly(ethene) film used to wrap freshly picked apples. The long chain has been drawn with only three repeat units. The packing company compares this synthetic polymer with paper made from naturally occurring cellulose. It needs a wrapping material that keeps moisture in but adds very little mass to each box of fruit. The table gives measurements made on equal-sized samples. Both samples were kept at 22 degrees C before testing.
| material | mass of one sheet / g | water lost from apples after 24 h / g |
|---|---|---|
| poly(ethene) film | 0.82 | 1.4 |
| cellulose paper | 2.35 | 4.9 |
(a) Give the name of the small molecule used to make poly(ethene). [1]
(b) Use Fig. 1 to describe what is meant by a repeat unit. [2]
(c) Use Table 1 to give one advantage of poly(ethene film for this use. [1]
(d) Give one environmental problem caused when poly(ethene packaging is discarded. [1]
A sports-clothing laboratory tests fibres for a reusable running top. Fig. 1 shows simplified chains in two fibres. Fibre A is a natural protein polymer from sheep wool. Fibre B is nylon, a synthetic polyamide. Equal masses of each fibre were soaked in detergent solution, rinsed with water and dried. The table shows the results from five wash cycles. The student wants a fibre that remains strong after washing and does not take a long time to dry.
| fibre | breaking force after five washes / N | drying time / min |
|---|---|---|
| wool | 38 | 94 |
| nylon | 61 | 43 |
(a) Give the term for a polymer made from amino acids. [1]
(b) Use Table 1 to choose the more suitable fibre for the running top. [1]
(c) Describe how the results support your choice. [2]
(d) Give one reason why some shoppers may still choose wool. [1]
Answer Details
Apple wrapping
(a) The monomer used to make poly(ethene) is ethene. [1]
(b) A repeat unit is a section of the polymer chain that repeats. It is joined many times to form a long chain. [2]
(c) Poly(ethene) film has lower mass, so it adds less mass to each fruit box. [1]
(d) Discarded poly(ethene) does not biodegrade readily and can persist as litter, potentially harming wildlife. [1]
Running-top fibres
(a) A polymer made from amino acids is a protein. [1]
(b) Nylon is the more suitable fibre. [1]
(c) Nylon has a greater breaking force, \(61\ \text{N}\) compared with \(38\ \text{N}\), and dries faster, \(43\ \text{min}\) compared with \(94\ \text{min}\). [2]
(d) Some shoppers may choose wool because it comes from a renewable, naturally occurring source or because it is biodegradable. [1]
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