Quick Lime
Lime, sometimes referred to as quicklime, is a term commonly applied to a number of related materials. Pure lime is calcium oxide (CaO) formed by “burning” a form of calcium carbonate such as limestone or marble (CaCO3). Carbon dioxide gas (CO2) is released and leaves lime behind.
Dolomite, a calcium magnesium carbonate (CaMg(CO3)2) can also be calcined to form dolomitic lime, which has different reactivity due to the presence of MgO. Lime can be mixed with water to form hydrated lime (Ca(OH)2), which some also call lime.
To further muddy the waters, in agriculture adding lime to the soil is not done with true lime but with limestone.
Hydrated Lime
Calcium hydroxide, traditionally called slaked lime, hydrated lime, slack lime, or pickling lime, is a chemical compound with the chemical formula Ca(OH)2. It is a colourless crystal or white powder, and is obtained when calcium oxide (called lime or quicklime) is mixed, or "slaked" with water.
It can also be precipitated by mixing an aqueous solution of calcium chloride and an aqueous solution of sodium hydroxide. The name of the natural, mineral form is portlandite. It is a relatively rare mineral, known from some volcanic, plutonic, and metamorphic rocks. It has also been known to arise in burning coal dumps.
When heated to 512 °C, the partial pressure of water in equilibrium with calcium hydroxide reaches 101 kPa that decomposes calcium hydroxide into calcium oxide and water.[1] A suspension of fine calcium hydroxide particles in water is called milk of lime.
The solution is called lime water and is a medium strength base that reacts violently with acids and attacks many metals in presence of water. It turns milky if carbon dioxide is passed through, due to precipitation of calcium carbonate.
