Much of the carbon dioxide in the Earth's early atmosphere is now locked up in limestone, which is mainly calcium carbonate, CaCO3\mathrm{CaCO_{3}}CaCO3.
When calcium carbonate is heated strongly, it releases this carbon dioxide:
CaCO3→CaO+CO2 \mathrm{CaCO_{3} \rightarrow CaO + CO_{2}} CaCO3→CaO+CO2Relative atomic mass (ArA_rAr): C = 12 O = 16 Ca = 40
What mass of carbon dioxide is locked up in 250 kg of calcium carbonate?
30 kg
110 kg
120 kg
140 kg
51 exam-style questions on OCR GCSE Chemistry 6.3 Interpreting and interacting with earth systems, covering 6.3.1 Formation and evolution of the atmosphere, 6.3.2 The greenhouse effect and climate change, 6.3.3 Sources and problems of atmospheric pollutants, and 6.3.4 Producing potable water. Each one has a worked solution and a mark scheme showing where the marks go.