[Chemistry Class Notes] on Uses of Limestone Pdf for Exam

Have you seen the Taj Mahal, one of the seven wonders of the world? If yes, then you must be amazed to see its majestic beauty, white colour and eternal testament to the artistic and scientific accomplishments of a wealthy empire. Do you know what the Taj Mahal is made of? If no, then the answer is Taj Mahal is made up of marble which is a mineral called Limestone. Not only the Taj Mahal but the outer covering of the Great Pyramid of Giza was also made up of Limestone. The Great Pyramid of Giza is also one of the seven wonders of the world. It must be understood that we have been using limestone for construction workk since ancient times. Before discussing its various uses, let’s understand what limestone is and its various properties. 

What is Limestone? 

Limestone is an extensively versatile mineral. It is a carbonated sedimentary rock that is formed predominantly on the seafloor where materials rich in calcium carbonates accumulate. Its main component is calcium carbonate (CaCO₃). This is the reason calcium carbonate is also called limestone. Marine organisms such as coral, foraminifera etc. leave their calcium carbonate shells behind when they die. About 10% of the sedimentary rocks are limestones.

 

Limestones are soluble in water and weak acids. It also contains variable amounts of silica in the form of chert. Limestone can be of yellow, white, or grey in colour. 

Characteristics of Limestone 

Few characteristics of limestone are listed below –

• It almost always has some impurities, that is why it’s not perfectly white in color.

• It is mainly formed by calcium carbonate shells of marine animals.

• It is a part of the diet of terrestrial animals. It is added in the diet of poultry animals to improve egg quality. 

• It is mostly found in the shallow ends of marine water. 

• Chalk is a type of limestone.

• It absorbs pollutants. 

• Limestone is able to form karst topography. 

• It reacts with hydrochloric acid and produces bubbles. This is the reason acid testing is considered one of the most reliable field tests for limestone. 

• When any type of limestone undergoes metamorphism, they recrystallize as marbles.
  

Uses of limestone 

Limestone is one of the important resources for human beings. It is an extremely versatile mineral that is used in various fields and in numerous ways. We can easily find objects made up of one or another form in almost every common household. A few of its uses are listed below –

• In building and decorative stones – Limestone has been used in construction since ancient times. Taj Mahal, the exquisite marble structure in Agra, India is an example of the usage of limestone in artistic accomplishments. Limestone is still being used in construction work in many ways. Its resistance to weather and aesthetic appeal makes it more suitable for this purpose. 

• Aggregates – Limestone is crushed and sorted into various sizes for its use for various purposes. It is one of the main components of concrete. It is coated with bitumen to make asphalt. Most of its aggregates are used in the formation of bases of roads, walls, paving slabs, decorative pieces etc. 

• Industrial purposes – Calcium carbonate is used in industries. It is used as a flux in steel making. It is also used for soil conditioning and latex treatment. It is the main ingredient of animal feed supplements (e.g. poultry grit).

• Lime burning – It has been used for lime burning since the 1920s. Lime burning is also called calcining. When limestone is heated at high temperature, it breaks down into lime (calcium oxide) and carbon dioxide gas. Reaction if given below of decomposition of limestone or calcium carbonate –
  

Thus, it is a raw material for manufacturing quicklime.

• Cement – Portland cement is a product of limestone which on mixing with aggregates makes concrete. 

• Agriculture – It is used as a soil conditioner. It is the main component of many fertilisers. It is used to neutralise acidic soils. 

• Petroleum reservoirs – Its geological formations are among the best petroleum reservoirs. 

• In pollution control – It reacts with sulphur dioxide so used in air pollution control as a reagent in flue – gas desulfurization. 

• In Glassmaking – Limestone is used in glassmaking.

• As a source of calcium – It is used as a source of calcium and its purified form is added in breads and cereals. 

• In mining – It is used in the mining process as it can suppress methane explosions. 

• To increase the alkalinity of water – It is used to increase the alkalinity of water to prevent pipe corrosion.

• In medicines – Calcium carbonate is used as a gastric antacid. It is also used as a phosphate binder for the treatment of hyperphosphatemia. It is also used as an inert filler for tablets. 

• In cosmetics – In many cosmetics products also it is used as filler.

• In sculptures – It easily mixes with clay and due to its white colour, it is used in making sculptures. It gives them a bright white colour as well. 

• Great Pyramid of Giza – Great Pyramid of Giza is one of the seven wonders of the world. Its outside covering is entirely made up of limestone. 

• As raw material for synthesis – It is used as raw material for the synthesis of many chemicals such as slaked lime, quicklime and mortar etc. 
  

The world’s largest limestone quarry is at Michigan Limestone in Rogers City, Michigan. The Megalithic Temples of Malta are entirely composed of limestone. The white cliffs of Dover are also made up of limestone. Generally, spectacular rocky outcrops and islands are bands of limestone emerging from the Earth’s surface long back. Thus, limestone is a very useful mineral for mankind.

 

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