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Stage 1 takes in heat energy, it is endothermic - Edexcel - GCSE Chemistry - Question 7 - 2020 - Paper 1
Question 7
Stage 1 takes in heat energy, it is endothermic. Explain the effect of increasing the temperature on the yield of the products of stage 1. (i) The overall equation... show full transcript
Worked Solution & Example Answer:Stage 1 takes in heat energy, it is endothermic - Edexcel - GCSE Chemistry - Question 7 - 2020 - Paper 1
Step 1
Explain the effect of increasing the temperature on the yield of the products of stage 1.
Answer
Increasing the temperature of an endothermic reaction, such as the one described in Stage 1, will shift the equilibrium to the right or in the forward direction. This occurs because the system seeks to absorb the added heat, thus increasing the yield of the products, which in this case are hydrogen and carbon monoxide.
Step 2
Calculate the maximum volume of hydrogen in dm³, measured at room temperature and pressure, that could be made in this reaction.
Answer
To calculate the maximum volume of hydrogen produced, we start with the given mass of methane, 0.40g. The molar mass of CH₄ is approximately 16 g/mol, so:
- Moles of CH₄ = 0.40 g / 16 g/mol = 0.025 moles.
From the balanced equation, 1 mole of CH₄ produces 4 moles of H₂:
- Moles of H₂ produced = 0.025 moles CH₄ × 4 = 0.1 moles H₂.
At room temperature and pressure (RTP), 1 mole of gas occupies 24 dm³:
- Volume of H₂ = 0.1 moles × 24 dm³/mole = 2.4 dm³.
Step 3
Evaluate the advantages and disadvantages of providing electrical energy in a spacecraft using hydrogen-oxygen fuel cells rather than chemical cells.
Answer
Advantages:
- Maintenance: Once set up, fuel cells require no maintenance, unlike chemical cells that need to be recycled or replaced periodically.
- Longevity: Fuel cells can operate as long as the hydrogen and oxygen are supplied.
- Fuel Utility: Fuel cells use hydrogen and oxygen directly, providing a more efficient energy conversion than chemical reactions in cells.
Disadvantages:
- Supply Requirements: Hydrogen and oxygen must be supplied, which can increase the complexity of the spacecraft's design.
- Storage Challenges: Storing hydrogen as a gas can be difficult due to its low density and flammability.
Conclusion:
While hydrogen-oxygen fuel cells offer significant advantages in maintenance and efficiency, the logistical challenges of storing and supplying fuel must be carefully considered when designing a spacecraft.