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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
In an endothermic reaction, increasing the temperature shifts the equilibrium position to the right or forward direction. This happens according to Le Chatelier's principle, which states that if a system at equilibrium is subjected to a change in temperature, pressure, or concentration, the system will adjust itself to counteract that change. As temperature increases, the yield of the products, in this case hydrogen and carbon monoxide, will also increase. Therefore, an increase in temperature will enhance the yield of the desired products.
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 find the maximum volume of hydrogen produced, we must first determine the moles of methane reacted:
- Molar mass of methane (CH₄) = 12 (C) + 4 (H) = 16 g/mol.
- Moles of methane = mass / molar mass = 0.40 g / 16 g/mol = 0.025 mol.
According to the balanced equation, 1 mole of CH₄ produces 4 moles of H₂. Therefore:
- Moles of hydrogen = 0.025 mol CH₄ × 4 = 0.1 mol H₂.
At room temperature and pressure (RTP), 1 mole of gas occupies 24 dm³, thus:
- Volume of hydrogen = moles × 24 dm³/mol = 0.1 mol × 24 dm³/mol = 2.4 dm³.
Therefore, the maximum volume of hydrogen produced is 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 Free: Once set up, fuel cells require no maintenance compared to chemical cells, which may need to be replaced after a certain time due to their limited lifespan.
- Sustainability: Fuel cells can operate as long as hydrogen and oxygen are supplied, offering a sustainable energy source for long missions.
- High Efficiency: Fuel cells tend to operate more efficiently than traditional chemical cells, converting energy directly to electricity with minimal waste.
- Resource Utilization: Any unused hydrogen can be used as drinking water, thus serving a dual purpose in a spacecraft.
Disadvantages:
- Supply Logistics: Hydrogen and oxygen need to be transported by spacecraft, adding complications to storage and safety measures.
- Safety Hazards: Hydrogen is a flammable gas, posing significant risks if not handled properly.
- Manufacturing Complexity: Producing fuel cells can be more complex and costly than conventional chemical cells.
Conclusion:
In conclusion, while both hydrogen-oxygen fuel cells and chemical cells have their respective merits, the choice often depends on specific mission requirements and available technology. Hydrogen-oxygen cells may be preferable for longer missions, but suitable reasons must be given to justify this choice.