The Cycle of Reactions involving Limestone and Products Made From it

Limestone is a sedimentary rock composed mainly of calcium carbonate (CaCO3).
When limestone is heated, it undergoes a chemical reaction called thermal decomposition. This process turns calcium carbonate into calcium oxide and carbon dioxide (CaCO3 -> CaO + CO2).
The common name for calcium oxide is ‘quicklime’ or ‘burnt lime.’ It has a strong, alkaline reaction with water and generates significant heat.
Adding water to quicklime (calcium oxide) creates slaked lime, also known as calcium hydroxide (CaO + H2O -> Ca(OH)2).
The process of adding water to calcium oxide is called slaking, which is highly exothermic, releasing a large amount of heat.
Calcium hydroxide is slightly soluble in water and is often referred to as limewater in its aqueous state.
When carbon dioxide is passed through limewater, a reaction occurs resulting in the formation of calcium carbonate (Ca(OH)2 + CO2 -> CaCO3 + H2O).
This reaction implies the process can be cycled, going from limestone (calcium carbonate) back to limestone via quicklime (calcium oxide) and slaked lime (calcium hydroxide).
Limestone and its products have many industrial uses, including in the manufacture of cement, glass, iron, steel, and concrete.
Limestone is also used to neutralise acidity in soils and in lakes, to purify sugar, and in the making of toothpaste.
Quicklime is used in the steel industry to remove impurities and in the manufacture of bricks.
Slaked lime is used in the food industry, such as for pickling and pH adjustment. It’s also used in wastewater treatment.

Remember, each of these substances - limestone, quicklime, and slaked lime - has distinct physical and chemical properties. Also worth noting is the environmental impact of limestone quarrying. While it provides essential raw materials, it can damage landscapes, create noise and dust pollution, and affect local wildlife. The industry must balance the demand for limestone with the environmental impact of quarrying.

Try to take time to understand this cycle thoroughly, as knowing how each reaction works will help you predict other similar chemical reactions.