Limestone

Limestone Keywords

• Calcium Carbonate - the main compound in limestone
• Glass - made of powered limestone heated to high temperatures with sand and sodium carbonate.
• Cement - made of powdered limestone and powdered clay
• Concrete - cement powder , sand and crushed rock
• Quicklime - heated limestone broken down (calcium oxide)
• Thermal decomposition - breaking down a chemical by heating
• Lime kiln - to make lots of quicklime in a furnace

Limestone is a sedimentary rock. Consisting mainly of Calcium carbonate (CaCO3). It is cheap, easy to obtai and has many uses.

Limestone can be used:

• As a building material
• for making mortar and concrete.

Limestone can be quarried, cut into blocks and used to build houses.

It can be eroded by acid rain but this is a long slow process.

When calcium carbonate is heated in a kiln it decomposes. This reaction is called thermal decomposition. It causes the calcium carbonate to break down into calcium oxide and carbon dioxide.

Magnesium, copper, zinc, calcium and sodium carbonates decompose on heating in a similar way. Some metal carbonates, e.g. others in Group 1, may not decompose at the temperatures reached by a Bunsen burner

The calcium oxide can then be reacted with water to produce calcium hydroxide. Calcium hydroxide can be used to neutralise soils and lakes, preventing crop failure.

Carbonates of other metals decompose in a similar way when they're heated.

Powdered limestone is roasted in a rotary kiln with powdered clay to produce dry cement. When sand and water are mixed in, mortar is produced.

Mortar is used to hold bricks and stones together. When aggregate, sand and water are mixed in, concrete is produced.