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Disposable cups are made from coated paper or poly(styrene) - AQA - GCSE Chemistry - Question 10 - 2018 - Paper 2
Question 10
Disposable cups are made from coated paper or poly(styrene). Table 6 shows information on the life cycle assessments (LCAs) of disposable cups. Table 6 | Raw mate... show full transcript
Worked Solution & Example Answer:Disposable cups are made from coated paper or poly(styrene) - AQA - GCSE Chemistry - Question 10 - 2018 - Paper 2
Step 1
Evaluate the use of coated paper compared with poly(styrene) to make disposable cups.
Answer
When comparing the use of coated paper and poly(styrene) for disposable cups, several factors must be considered:
Raw Materials
- Sustainability: Wood, used for coated paper, is a renewable resource; however, excessive deforestation can lead to biodiversity loss. Conversely, crude oil, used for poly(styrene), is finite and its depletion poses serious environmental concerns.
- Environmental Impact: The extraction of crude oil is associated with pollution and habitat destruction, impacting both local ecosystems and global climate.
Manufacturing Considerations
- Energy Requirements: Producing coated paper requires more energy (550 kJ) compared to poly(styrene) (200 kJ). This indicates a higher carbon footprint for paper production, though it is noted that the energy source can be renewable.
- Labor and Resources: Paper production can require more labor and logistics, while poly(styrene) can be manufactured using less invasive techniques, though at the cost of environmental sustainability.
Disposal and Environmental Effects
- Coated paper is biodegradable and will decompose, significantly reducing its landfill impact. In contrast, poly(styrene) is not biodegradable and persists in the environment, contributing to long-lasting pollution.
- Both types of cups can cause litter; however, the ecological consequences of poly(styrene) may be more severe given its non-degradable nature.
Conclusion
Overall, while coated paper may incur higher energy costs during production, its biodegradable nature offers significant environmental advantages over poly(styrene), which is sustainable only in terms of its immediate manufacturing benefits.
Step 2
Calculate the energy needed to produce 1.00 kg of coated paper cups.
Answer
To calculate the energy required to produce 1.00 kg of coated paper cups, we use the data from Table 6:
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Determine the mass of one cup: 8.3 g.
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Energy to produce one cup: 550 kJ.
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Convert 1.00 kg to grams: 1.00 kg = 1000 g.
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Calculate the number of cups in 1.00 kg:
\
[ \text{Number of cups} = \frac{1000 \text{ g}}{8.3 \text{ g/cup}} \approx 120.48 \text{ cups} ]
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Calculate the total energy required for 120.48 cups: \
[ \text{Total Energy} = 120.48 \text{ cups} \times 550 \text{ kJ/cup} \approx 66264 \text{ kJ} ]
Thus, the energy needed to produce 1.00 kg of coated paper cups is approximately:
[ 6.63 \times 10^4 \text{ kJ} ]
Step 3
Explain why melamine does not melt when heated.
Answer
Melamine is classified as a thermosetting polymer, which means that its structure is highly cross-linked. This cross-linking creates a stable and rigid network of polymer chains that do not separate when subjected to heat.
Key Reasons:
- Cross-linking: The bonds formed between the polymer chains make melamine resistant to deformation and melting under heat.
- Thermal Stability: Instead of melting, melamine will decompose when exposed to higher temperatures, maintaining its structural integrity up to a certain limit.
This property makes melamine suitable for various applications, including non-disposable cups, where high heat resistance is essential.