Calcium oxide has been known since ancient times. The Roman writer Cato the Elder (234 – 149 BC) mentioned one method of making the compound in 184 BC. By the early fifteenth century, many Europeans were using calcium oxide (generally referred to as lime) in the construction of buildings. The Scottish chemist Joseph Black (1728–1799) performed some of the earliest scientific studies of calcium oxide. He found that when the compound is exposed to air, it combines with carbon dioxide to produce calcium carbonate.
Calcium oxide is a chemical compound that has colourless, odourless properties and was used since the early times. The formula for calcium oxide is CaO. It is an amorphous substance that is in a crystalline or powdery solid form. Calcium oxide is also called quick lime, caustic lime or burnt lime. In its pure form, calcium oxide is white or off grey in colour. On the other hand, it is yellow or brownish in colour in the presence of impurities, such as iron, magnesia, silica or alumina. Calcium oxide also exists in the colours reds and muted browns.
The main primary elements which constitute calcium oxide are calcium and oxygen.It is prepared by heating calcium carbonate (e.g. limestone) in a distinct lime kiln to about 500°C to 600°C, decomposing it into the oxide and carbon dioxide.This process of obtaining burnt lime is called calcification. It starts with decomposing the natural components at high temperatures while maintaining they do not reach the melting point. This process is done by heating them at temperatures ranging from 1070 degrees Celsius to 1270 degrees celsius.
CaCO₃ → CaO + CO₂
Calcium oxide is used in industries that make porcelain and glass. It is also used for purifying sugar, in preparing bleaching powder, calcium carbide, and calcium cyanamide. Its other uses are in water softeners, mortars, and cement.
Calcium oxide (CaO), is generally known as quicklime or burnt lime, it is a commonly used chemical compound. It is solid at room temperature. The broadly used word lime means calcium-containing inorganic materials, in which oxides and hydroxides of calcium, magnesium, aluminium, silicon, and iron are present. By contrast, quicklime precisely applies to the single chemical compound calcium oxide. But commercial lime frequently contains impurities.
Calcium oxide is also widely used in medicines and pesticides. Due to alkali being available in affordable amounts, calcium oxide is one of the essential ingredients in making caustic soda. It is also used in the manufacturing of steel, paper, and cement.
The second most vital use of calcium oxide is in pollution control devices. Smoke that ejects from any industry’s smokestack contains high amounts of sulfur and nitrogen. When sulfur and nitrogen are combined with water, it morphs into new substances, such as nitric acid and sulphuric acid.
To prevent such harmful chemical compositions from getting in contact with nature, machines called scrubbers are installed. These devices have large compounds of calcium oxide which help in neutralising the high amounts of sulphuric acid and nitric acid.
