Thermal Decomposition of Calcium Carbonate

Thermal Decomposition

Calcium Compounds

• The thermal decomposition of calcium carbonate produces calcium oxide.
• Calcium oxide is known as quicklime.
• \(CaCO_3 (s) \rightarrow CaO(s) + CO_2(g)\)
• When calcium oxide is reacted with water, calcium hydroxide is produced.
• Calcium hydroxide is known as slaked lime. When it is dissolved in water, it is known as limewater.
• \(CaO(s) + H_2O(l) \rightarrow Ca(OH)_2(aq)\)
• When calcium hydroxide is reacted with carbon dioxide, calcium carbonate is formed.
• The calcium carbonate is insoluble in water and this is why limewater can be used to test for the presence of carbon dioxide.
• \( Ca(OH)_2(aq)+CO_2(g)\rightarrow CaCO_3 (s) + H_2O(l)\)

Production of Cement

• \(\bullet\) Cement is a key ingredient in the manufacture of concrete
• \(\bullet\) Limestone and clay are heated strongly, causing the limestone to thermally decompose.
• \(\bullet\)The result calcium oxide then reacts with clay to form calcium silicates.
• \(\bullet\)Water is added, resulting in a series of complex reactions that form hydrated silicates
• \(\bullet\)These make the cement hard
• \(\bullet CaCO_3 (s) \rightarrow CaO(s) + CO_2(g)\)
• \(\bullet CaO(s) +SiO_2(s) \rightarrow CaSiO_3(s)\)