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This question is about the Earth’s atmosphere and the Earth’s resources - AQA - GCSE Chemistry: Combined Science - Question 5 - 2022 - Paper 2
Question 5
This question is about the Earth’s atmosphere and the Earth’s resources. 1. After the formation of the Earth’s early atmosphere, the amounts of nitrogen and oxygen ... show full transcript
Worked Solution & Example Answer:This question is about the Earth’s atmosphere and the Earth’s resources - AQA - GCSE Chemistry: Combined Science - Question 5 - 2022 - Paper 2
Step 1
Explain the main changes in the amounts of nitrogen and oxygen in the Earth’s atmosphere.
Answer
The levels of nitrogen in the Earth’s atmosphere increased significantly due to emissions from volcanoes and the process of denitrification. As a result, nitrogen became the most abundant gas in the atmosphere. Conversely, the amount of oxygen increased primarily as a result of photosynthesis by early plants. Thus, the dynamic between these gases changed drastically over geological timescales.
Step 2
Describe how coal was formed from the carbon dioxide present in the Earth’s early atmosphere.
Answer
Coal formation began as carbon dioxide was utilized by plants during photosynthesis. Over millions of years, dead trees that captured carbon dioxide became buried and subjected to heat and pressure, transforming them into coal.
Step 3
Suggest why the combustion of 1.0 kg of coal produces more carbon dioxide than the combustion of 1.0 kg of natural gas.
Answer
Coal has a higher proportion of carbon compared to natural gas. Therefore, burning coal releases more carbon dioxide because more carbon is converted into carbon dioxide in the combustion process.
Step 4
Describe how bioleaching is used to extract copper from low grade ores.
Answer
Bioleaching involves the use of bacteria to extract copper from copper-containing compounds in low-grade ores. These bacteria produce solutions that help dissolve copper, which can then be recovered through displacement or electrolysis.
Step 5
Calculate the mass of ash produced from burning 1000 kg of plants.
Answer
To calculate the mass of ash produced, first determine the nickel content in the plants:
ext{Nickel in plants} = 1000 ext{ kg} imes rac{0.792}{100} = 7.92 ext{ kg}
Next, use the percentage of nickel in ash to find the total mass of ash:
ext{Ash mass} = rac{7.92 ext{ kg}}{0.048} = 165 ext{ kg}
Finally, convert to grams:
Thus, the mass of ash produced is .