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5 (a) Limestone is a natural form of calcium carbonate - Edexcel - GCSE Chemistry - Question 5 - 2013 - Paper 1
Question 5
5 (a) Limestone is a natural form of calcium carbonate. Explain why calcium carbonate can be used to treat waste gases produced in coal-fired power stations. (3) (... show full transcript
Worked Solution & Example Answer:5 (a) Limestone is a natural form of calcium carbonate - Edexcel - GCSE Chemistry - Question 5 - 2013 - Paper 1
Step 1
Explain why calcium carbonate can be used to treat waste gases produced in coal-fired power stations.
Answer
Calcium carbonate, found in limestone, acts as a neutralizing agent for acidic gases emitted from coal combustion, particularly sulfur dioxide. When calcium carbonate comes into contact with these gases, it reacts to form calcium sulfate, which reduces pollution levels. Additionally, calcium carbonate can absorb impurities from coal, enhancing combustion efficiency and reducing overall emissions.
Step 2
Step 3
Step 4
Explain how the three rock layers were formed.
Answer
Limestone is formed from layers of sediment, primarily made up of shells and skeletons of marine organisms. Over long periods, these sediments build up and become compacted, solidifying into limestone.
Marble forms from limestone that has undergone metamorphism due to heat and pressure within the Earth. This process changes the mineral structure of the limestone, resulting in marble.
Granite, an igneous rock, originates from magma that cools and solidifies beneath the Earth’s surface. This cooling allows crystals to form, which gives granite its characteristic texture.