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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
Nitrogen has increased in the Earth’s atmosphere due to the emissions from volcanic activity, leading to a rise in atmospheric nitrogen levels. This is primarily because nitrogen gas was released during volcanic eruptions.
Oxygen levels have also increased, largely due to photosynthesis carried out by early plants and algae. This process converted carbon dioxide into oxygen, significantly raising the concentration of oxygen in the atmosphere over geological timescales.
Step 2
Describe how coal was formed from the carbon dioxide present in the Earth’s early atmosphere.
Answer
Coal formation occurred when carbon dioxide was absorbed by plants during photosynthesis. As these plants died, they accumulated in anoxic environments, which meant they were not exposed to oxygen. Over millions of years, these layers of plant matter were subjected to heat and pressure, leading to the conversion of carbon-rich plant material into coal.
Step 3
Step 4
Describe how bioleaching is used to extract copper from low grade ores.
Answer
Bioleaching involves using bacteria to extract metals from low grade ores. These bacteria can oxidize the metal compounds within the ore, facilitating the release of copper into a leachate solution. This solution can then be processed to recover copper through displacement or electrolysis.
Step 5
Calculate the mass of ash produced from burning 1000 kg of plants.
Answer
To find the mass of ash produced:
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Calculate the nickel in the plants:
Nickel in 1000 kg of plants =
Amount of nickel = 0.792/100 * 1000 kg = 7.92 kg
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Since the ash contains 4.80% nickel:
Let x be the mass of ash produced.
0.048 * x = 7.92 kg
x = 7.92 kg / 0.048
x = 165 kg
Thus, the mass of ash produced from burning 1000 kg of plants is 165,000 grams, or in standard form: 1.65 x 10^5 g.