Much of the carbon dioxide in the Earth's early atmosphere is now locked up in limestone, which is calcium carbonate, CaCO3\mathrm{CaCO_{3}}CaCO3. Carbon dioxide dissolved in the oceans. Marine organisms then used the dissolved carbon dioxide to make shells of calcium carbonate. When the organisms died, their shells formed limestone over millions of years.
Suggest why the formation of limestone was important in removing carbon dioxide from the atmosphere over a long time, even though carbon dioxide dissolves in water.
Calculate the volume of carbon dioxide, at room temperature and pressure, that was removed from the atmosphere to form 1.00 kg of calcium carbonate. Assume that one mole of carbon dioxide forms one mole of calcium carbonate.
Relative atomic masses: Ca = 40, C = 12, O = 16. The volume of one mole of any gas at room temperature and pressure is 24 dm³.
Air today contains 0.04 % carbon dioxide by volume. Calculate the volume of air that contains the volume of carbon dioxide in your answer to (b).
Cement is made by heating limestone in a kiln that burns fossil fuels.
CaCO3(s)→CaO(s)+CO2(g)\mathrm{CaCO_{3}(s)} \rightarrow \mathrm{CaO(s)} + \mathrm{CO_{2}(g)}CaCO3(s)→CaO(s)+CO2(g)
Explain why making cement increases the amount of carbon dioxide in the atmosphere in two different ways.
97 exam-style questions on Edexcel GCSE Chemistry 9.2 Earth and atmospheric science, covering 9.2.1 The Earth's early atmosphere, 9.2.2 How the atmosphere evolved, 9.2.3 Chemical test for oxygen, and 9.2.4 The greenhouse effect and climate change. Each one has a worked solution and a mark scheme showing where the marks go.